Dissertations / Theses on the topic 'Transiti planetari'
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1
Giacobbe, Paolo. "Photometric transit search for planets around cool stars from the Western Italian Alps: the APACHE survey." Doctoral thesis, Università degli studi di Trieste, 2014. http://hdl.handle.net/10077/9965.
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2012/2013Small-size ground-based telescopes can effectively be used to look for transiting rocky planets around nearby low-mass M stars using the photometric transit method. Since 2008, a consortium of the Astrophysical Observatory of Torino (OATo-INAF) and the Astronomical Observatory of the Autonomous Region of Aosta Valley (OAVdA) have been preparing for the long-term photometric survey APACHE (A PAthway toward the Characterization of Habitable Earths), aimed at finding transiting small-size planets around thousands of nearby early and mid-M dwarfs. APACHE uses an array of five dedicated and identical 40-cm Ritchey-Chretien telescopes and its routine science operations started at the beginning of summer 2012. Here I present the results of the `pilot study', a year-long photometric monitoring campaign of a sample of 23 nearby dM stars, and of the APACHE survey first year data. In these studies, I set out to (i) demonstrate the sensitivity to > 2 Rearth transiting planets with periods of up to a few days around our programme stars, through a two-fold approach that combines a characterization of the statistical noise properties of our photometry with the determination of transit detection probabilities via simulations; and (ii), where possible, improves our knowledge of some astrophysical properties (e.g. activity, rotation) of our targets by combining our differential photometric measurements with spectroscopic information from the long-term programme GAPS with the HARPS-N spectrograph on the Telescopio Nazionale Galileo. Furthermore, cool M dwarfs within a few tens of parsecs from the Sun are becoming the focus of dedicated observational programs in the realm of exoplanet astrophysics that will make use of astrometric measurements. I present numerical simulations to gauge the Gaia potential for precision astrometry of exoplanets orbiting a sample of known dM stars within ~ 30 pc from the Sun. I then investigate some aspects of the synergy between the astrometric data expected from the Gaia mission on nearby M dwarfs and the APACHE program.
XXV Ciclo
1985
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Aigrain, Suzanne. "Planetary transits and stellar variability." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614684.
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McQuillan, Amy. "Stellar variability and rotation in Kepler planetary transit search data." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:802a873d-650f-4f0b-b814-f8397b2798e2.
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The recent space-based exoplanet transit searches, CoRoT and Kepler, have revolutionised the field of stellar variability. In this thesis I exploit the public Kepler data to characterise stellar variability, and study rotation periods. For the study of stellar variability it is a complicated but necessary process to remove instrumental systematics while maintaining intrinsic stellar signal. I was involved in the development of a new correction method for systematics, denoted ARC (Astrophysically Robust Correction). This method relies on the removal of a set of basis functions that are determined to be present in small amounts across many light curves. Using the first month of Kepler data, corrected with the ARC method, I studied the variability properties of main sequence stars as a function of fundamental stellar parameters. I find that the fraction of stars with variability greater than that of the Sun is 60%, and confirm the trend of increasing variability with decreasing effective temperatures. I show tentative evidence that the more active stars have lower proper motions and may be located closer to the galactic plane. I also investigate the frequency content of the variability, showing that there exist significant differences in the nature of variability between spectral types, with a trend towards longer periods at later spectral types. In order to exploit the full potential of the Kepler data for stellar rotation period measurement, I developed a novel method of period detection for use on star spot modulated light curves. Standard approaches to period detection are based on Fourier decomposition or least-squares fitting of sinusoidal models. However, typical stellar light curves are neither sinusoidal nor strictly periodic. Therefore, I developed an algorithm for period detection based on the autocorrelation function (ACF) of the light curve. Because the ACF measures only the degree of self-similarity of the light curve at a given time lag, the period remains detectable even when the amplitude and phase of the photometric modulation evolve significantly. I applied the ACF method for the sample of M-dwarfs observed during the first 10 months of the Kepler mission, and detected rotation periods in 1570, ranging from 0.37-69.7 days. The rotation period distribution is clearly bimodal, with peaks at ~19 and ~33 days, hinting at two distinct waves of star formation. These two peaks form two distinct sequences in period-temperature space, with the period decreasing with increasing temperature. In a natural continuation to this work I applied measured periods for 1000 stars in each of the F, G and K-dwarf sets observed by Kepler, and combined these with the M-dwarf results. The trend of increasing rotation period with increasing mass is clear throughout, as the observations fall along a wide by distinct sequence. Comparison to the rotational isochrones of Barnes (2007) show an overall agreement, although the dataset, which I believe is the largest set of rotation period measurements for main sequence stars, shows addition detail, not captured by the gyrochronology relations. This includes a dip in the rotation period distribution at ~0.6 M⊙ and a steep increase in period for the M-dwarfs. I also applied the ACF method to the Kepler exoplanet candidate host stars and used the results to search for evidence of tidal interaction between the star and planet. I show that for the majority of exoplanet host stars, spin-orbit interaction will not have affected the stellar rotation period, permitting the application of gyrochronology for age determination. A comparison of the host stars with a sample of field stars selected to match their temperature and magnitude distribution also indicates no significant difference in the period or amplitude distributions of the two sets. The only notable variation is the lack of planets around the very fast rotators across all spectral types.
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De, Marchi Fabrizio. "Variable stars and planetary transit search in super metal-rich open clusters." Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3427100.
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This PhD thesis presents the analysis of a large sample of photometric data relative to the super metal-rich open clusters NGC6791 and NGC6253.
The main goal of the surveys was the search for extrasolar planets using the transits method.
I contributed to the extrasolar planet search by making numerical simulations in order to estimate the number of expected transiting planets. Moreover I analyzed the entire sample of light curves in order to find variable stars.
I discovered 260 new variable stars in the field of NGC6791 and 597 in the field of NGC6253.
The classification of all variables is presented and discussed in this work.
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Street, Rachel. "A search for extra-solar planetary transits in the field of open cluster NGC 6819." Thesis, University of St Andrews, 2002. http://hdl.handle.net/10023/12939.
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The technique of searching for extra-solar planetary transits is investigated. This technique, which relies on detecting the brief, shallow eclipses caused by planets passing across the line of sight to the primary star, requires high-precision time-series photometry of large numbers of stars in order to detect these statistically rare events. Observations of ~ 18000 stars in the field including the intermediate-age open cluster NGC 6819 are presented. This target field contrasts with the stellar environment surveyed by the radial velocity technique, which concentrates on the Solar neighbourhood. I present the data-reduction techniques used to obtain high-precision photometry in a semi-automated fashion for tens of thousands of stars at a time, together with an algorithm designed to search the resulting lightcurves for the transit signatures of hot Jupiter type planets. I describe simulations designed to test the detection efficiency of this algorithm and, for comparison, predict the number of transits expected from this data, assuming that hot Jupiter planets similar to HD 209458 are as common in the field of NGC 6819 as they are in the Solar neighbourhood. While no planetary transits have yet been identified, the detection of several very low amplitude eclipses by stellar companions demonstrates the effectiveness of the method. This study also indicates that stellar activity and particularly blending are significant causes of false detections. A useful additional consequence of studying this time-series photometry is the census it provides of some of the variable stars in the field. I report on the discovery of a variety of newly-discovered variables, including Algol-type detached eclipsing binaries which are likely to consist of M-dwarf stars. Further study of these stars is strongly recommended in order to help constrain models of stellar structure at the very low mass end. I conclude with a summary of this work in the context of other efforts being made in this field and recommend promising avenues of further study.
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Ballerini, Paola. "Effects of starspots activity on optical and near infrared observations of planetary transits." Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1377.
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In this thesis, I report on the effects that magnetic stellar activity of solar-type stars induces on stellar light curves involved in the photometric technique for the detection and characterization of transiting extra-solar planets that is one of the most effective detection methods, the first being the radial velocity technique.
Stellar magnetic activity is a source of noise in the study of the transits of extra-solar planets since it induces flux variations that significantly affect the transit depth determination and the derivations of planetary and stellar parameters. Surface brightness inhomogeneities, such as starspots or bright faculae, on star disc have an intrinsic dependence on wavelength and thus on the stellar colours. The colour dependence of stellar activity may significantly influence the characterization of planetary atmospheres since it produces stellar flux variations that may mimic those due to the presence of molecular or atomic species in the transmitted planetary spectra. In this thesis I focus on the effects due essentially to stellar spots present in the visible hemisphere of solar-type stars. The proposed method is a theoretical one, aiming to predict the starspot-induced effects with the use of stellar atmospheric models and I present a systematic approach to quantify the corresponding stellar flux
variations as a function of wavelength bands. Therefore I consider a star with spots covering a given fraction of its disc and model the variability in both the UBVRIJHK photometric system and the Spitzer/IRAC wavebands for dwarf stars from G to M spectral types. Then I compare starspot-induced flux variations in these different passbands with planetary transits and quantify how they affect the determination of the planetary radius and the analysis of the transmission spectroscopy in the study of planetary atmospheres. My results suggest that the monitoring of the systems by using broad-band photometry, from visible to infrared, helps to constrain spots effects by estimating the R parameter, i.e. the ratio of the relative variations in the stellar fluxes at short wavelength optical bands (e.g., U or B) to near-infrared ones (e.g., J or K). Its numerical value can be used to distinguish starspot brightness dips from planetary transits in a single stellar light curve.
In addition to the perturbations in the measurement of the planetary radius, the perturbations in the transit light curve profiles due to starspots can affect the determinations of orbital parameters, i.e., the relative semi-major axis and the inclination of the planetary orbit, that are directly derived by fitting procedure of the transit light curves. These distortions in the transit light curves have a significant impact on the derivation of stellar parameters and, above all, on the stellar density thus bothering the stellar evolutionary estimates.
The results derived from the synthetic photometric analysis are presented and discussed in Ballerini et al. 2012.
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Nisley, Ishara. "Transit timing variations of the exoplanet K2-25b." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/117447.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2017.Cataloged from PDF version of thesis. "May 16, 2017." "This thesis was submitted to the Institute Archives without all the required signatures"--Disclaimer Notice page.
Includes bibliographical references (page 53).
Transit light curves of the exoplanet K2-25b were studied to examine the possibility of transit timing variations (TTVs) in the system, which could imply the presence of a perturbing planet. Observations of K2-25b transits were taken using 14-inch and 24-inch telescopes at Wallace Astrophysical Observatory. Two transit light curves were fit using an MCMC implementation to find the orbital period, planetary radius, and semi-major axis. A new period calculation yielded an orbital period of 3.48457 +/-0.00004, consistent with the period of 3.484552 +0.000044/-0.000036 from Mann et al. 2016. No significant variations were found in the midtimes of the new transit observations when comparing them to the midtime originally published in Mann et al. 2016. Future observations will require smaller uncertainties to meaningfully constrain the mass and period of potential perturbing planets. Signal-to-noise ratio calculations showed that telescopes over approximately 2.2 meters in diameter have better potential to detect small TTVs.
by Ishara Nisley.
S.B.
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Adams, Elisabeth Rose. "Transit timing with fast cameras on large telescopes." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59737.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 171-178).
Timing and system parameters were measured for seven transiting exoplanets: OGLETR- 56b (11 transits), OGLE-TR-132b (7), OGLE-TR-111b (6), OGLE-TR-113b (6), CoRoT-2b (3), OGLE-TR-10b (3), and XO-2b (2). Ground-based observations of 38 transits were made using three new frame-transfer instruments: POETS and MagICe2v on the 6.5m Magellan telescopes, and MORIS on the 3m IRTF. For each planet, all transit light curves including available literature data were jointly fit using a Monte Carlo Markov Chain method, providing accurate new values for the planetary radius and other parameters. Transit ephemerides have been updated and transit midtimes have been investigated for potential transit timing variations (TTVs) caused by other planets or moons. Our transit midtime analysis contradicts a claimed TTV for OGLE-TR-111b (Diaz et al., 2008), finding no evidence in data from 2005-2009. The radius, 1.019 + 0.026 Rj, is intermediate to previous values (Winn et al., 2007; Diaz et al., 2008). We confirm the radius of OGLE-TR-56b, which previously had only one light curve (Pont et al., 2007), as 1.332 ± 0.063 Rj, but find a longer duration by 15 minutes, while the orbital period, 1.2119094 ± 0.0000024, is unchanged. Times for OGLE-TR-10b are consistent with the ephemeris of Holman et al. (2007), though two literature transits show large deviations (586 ± 86 s; Pont et al., 2007) and (-612 ± 26 s; Bentley et al., 2009). Times for four planets (OGLE-TR-113b, OGLE-TR-132b, CoRoT-2b, and XO-2b), with midtime errors as small as 9 s, agree with published ephemerides and show no signs of TTVs. The orbital period of OGLE-TR-113b derived from new data from 2007-2009, however, is shorter by 0.24 ± 0.12 s compared to the period calculated for literature data from 2002 and 2005. If confirmed, this would be the first detection of a change in the orbital period of an exoplanet, which could be caused by orbital decay as the planet falls onto its star.
by Elisabeth Rose Adams.
Ph.D.
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Morley, Caroline V. "Measuring transit timing variations of exoplanets using small telescopes." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/114139.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 57-58).
Transits of exoplanets were observed from June 2009 through January 2010. Six transit light curves are presented in this paper for three planets: WASP-10b, WASP- 11/HAT-P-10b, and TrES-3. Measurements of the planetary radii, semi-major axis, transit duration, and period confirmed literature values to within two sigma. Transit timing variations were not observed in these systems, but calculations show that it would be possible to measure transit timing variations induced by large exomoons (greater than about 6 Earth masses) in the WASP-11/HAT-P-10b system. Challenges of exoplanet observation from small telescopes are discussed. It was determined that overall, transit measurements of many exoplanets using small telescopes can be successful and scientifically useful.
by Caroline V. Morley.
S.B.
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DeCroix, David Scot. "Large-eddy Simulations of the Convective and Evening Transition Planetary Boundary Layers." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20010319-182404.
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Large-eddy simulation (LES) is a very useful tool in computationalfluid dynamics. The LES model allows one to solve a filtered set of theNavier-Stokes equations, thereby explicitly resolving scales of motionlarger than the discretization or grid size. Those motions smaller thanthe grid size are parameterized using a so-called subgrid scale model.
In this series of papers, we will use the TASS LES model, originallya cloud model, which has been modified to simulate planetary boundarylayer turbulence. We will first introduce the LES model and a newgrid-nesting method for the LES. Then we will present simulations ofthe convective planetary boundary layer, and then use the LES to studythe decay of convective planetary boundary layer turbulence to a stablystratified state.
The LES model has been modified to include a grid nesting capability.Grid meshes of higher resolution may be embedded within the LES enablingone to resolve smaller scales of motion (turbulence) than would bepossible by using a single grid mesh. The grid nesting methodology isdescribed in detail in Chapter 2.
In Chapter 3, the nested-grid LES will be applied to thesimulation of the convective planetary boundary layer. We will usea total of three grid meshes to increase the resolution in the surfacelayer, allowing a detailed analysis of the turbulence near the surface ofthe earth.
In Chapter 4, we will focus on applying Rayleigh Benardconvection criteria, using a linearized perturbation method,to the surface layer of a CBL produced by large-eddy simulation.Similarities and differences will be discussed between the LESproduced surface layer and classical Rayleigh-Benard convection theory.
In Chapter 5, using a large-eddy simulation model, we willexamine in detail the turbulent kinetic energy (TKE) budget during theevening transition. The simulation will be performed in order to compareto observations gathered at the Dallas-Fort Worth International Airport,Fort-Worth, TX. during September and October 1997.
In Chapter 6 the decay of planetary boundary layerturbulence during the evening transition will be studied. In previousstudies of the decay of turbulence, the effects of mean winds and shearsdue to pressure gradient on the turbulence decay was not considered.We propose to examine the effects of increasing geostrophic wind onthe convective boundary layer and its transition or decay to a stablecondition. Finally, the overall conclusions of each chapter will bepresented.
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Cao, Qin Ph D. Massachusetts Institute of Technology. "Seismic imaging of the mantle transition zone." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/70773.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references.
In this thesis, we developed a generalized Radon transform of SS precursors for large-scale, high-resolution seismo-stratigraphy of the upper mantle transition zone. The generalized Radon transform (GRT) is based on the single scattering approximation and maps singularities (reflections) in broad-band data into singularities (reflectors/scatters) in the medium. It is able to detect and characterize mantle discontinuities at a lateral resolution of several hundred kilometers. Synthetic tests with realistic source-receiver distributions demonstrate that the GRT is able to detect and image deep mantle interfaces at correct depths, even in the presence of noise, depth phases, phase conversions, and multiples generated by reverberation within the transition zone. We apply the GRT to ~1,600,000 broadband seismograms to delineate transition zone interfaces beneath distinct tectonic units, including a cross-section in the northwest Pacific Ocean that is far away from known down- and up-wellings, the volcanic islands of Hawaii, and the northwest Pacific subduction system. We account for smooth 3D mantle heterogeneity using first-order perturbation theory and independently derived global tomography models. Through integration with mineral physics data, the GRT seismic sections can put important constraints on the mantle temperature and mineralogy of the transition zone. Our GRT imaging results beneath the Central Pacific (including the Hawaii hotspot) reveal a more complicated mantle convection picture than a thin narrow vertical mantle "plume" passing through the transition zone. We found an 800- to 2000-kilometer-wide thermal anomaly (with a maximum temperature increase of -300 to 400 kelvin) deep in the transition zone west of Hawaii, by explaining the 410 and 660 km discontinuity topographies with olivine and garnet transitions in a pyrolitic mantle. According to our geodynamical modeling study of mantle upwellings, this might suggest that the hot materials feeding the Hawaii volcanoes do not rise from the lower mantle directly through a narrow vertical plume but may accumulate near the base of the transition zone before being entrained in flow toward Hawaii. In the GRT images of the subduction system, we found a deepened 660 km discontinuity in the slab that penetrates directly into the lower mantle according to tomography results. In another cross-section, where tomography results show that the slab is stagnant above the top of the lower mantle, we found broadening of the 660 km discontinuity signals at both edges of the slab. No corresponding uplift of the 410 km discontinuity is found. However, deepening of the 410 km discontinuity is observed beneath the continental side of the subduction system in both cross-sections, indicating hot anomalies at 410 km depth at the continental side if only the thermal effect is playing a role.
by Qin Cao.
Ph.D.
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Lockhart, Matthew S. M. Massachusetts Institute of Technology. "A transit-timing variation study of the extrasolar planet TrES-3." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53108.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2009.Includes bibliographical references (p. 105-106).
Portable Occultation Eclipse and Transit System (POETS) detectors [7] mounted on the Wallace Astrophysical Observatory (WAO) 0.8m and NASA Infrared Telescope Facility (IRTF) 3m telescopes are used to observe five stellar transit events of the extrasolar planet TrES-3 [5]. Model light curves are fit to the five data sets and transit midtimes are determined. Midtimes obtained in this study, along with midtimes reported by Sozzetti et al. (2008) [8], are compared to the ephemeris of the planet. The transit timing variation (TTV) of each midtime is calculated. Based on these data the presence of a third body in the TrES-3 system cannot be determined. Mass and period of a hypothetical perturbing body are calculated for several illustrative cases.
by Matthew Lockhart.
S.M.
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Bowens-Rubin, Rachel (Rachel A. ). "Feasibility-study for space-based transit photometry using mid-sized nanosatellites." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/77872.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 85-88).
The photometric precision needed to measure a transit of small planets cannot be achieved by taking observations from the ground, so observations must be made from space. Mid-sized nanosatellites can provide a low-cost option for building an optical system to take these observations. The potential of using nanosatellites of varying sizes to perform transit measurements was evaluated using a theoretical noise budget, simulated exoplanet-transit data, and case studies to determine the expected results of a radial velocity followup mission and transit survey mission. Optical systems on larger mid-sized nanosatellites (such as ESPA satellites) have greater potential than smaller mid-sized nanosatellites (such as CubeSats) to detect smaller planets, detect planets around dimmer stars, and discover more transits in RV followup missions.
by Rachel Bowens-Rubin.
S.M.
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Miles-Páez, Paulo A., Stanimir Metchev, Kevin L. Luhman, Massimo Marengo, and Alan Hulsebus. "The Prototypical Young L/T-Transition Dwarf HD 203030B Likely Has Planetary Mass." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/627091.
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Upon its discovery in 2006, the young L7.5 companion to the solar analog HD 203030 was found to be approximate to 200 K cooler than older late-L dwarfs, which is quite unusual. HD. 203030B offered the first clear indication that the effective temperature at the L-to-T spectral type transition depends on surface gravity: now a well-known characteristic of low-gravity ultra-cool dwarfs. An initial age analysis of the G8V primary star indicated that the system was 130-400 Myr old, and so the companion would be between 12 and 31 M-Jup. Using moderate-resolution near-infrared spectra of HD. 203030B, we now find features of very low gravity comparable to those of 10-150 Myr old L7-L8 dwarfs. We also obtained more accurate near-infrared and Spitzer/IRAC photometry, and we find a (J - K) MKO color of 2.56 +/- 0.13 mag-comparable to those observed in other young planetary-mass objects-and a luminosity of log (L-bol/L-circle dot) = -4.75 +/- 0.04 dex. We further re-assess the evidence for the young age of the host star, HD 203030, with a more comprehensive analysis of the photometry and updated stellar activity measurements and age calibrations. Summarizing the age diagnostics for both components of the binary, we adopt an age of 100 Myr for HD 203030B and an age range of 30-150 Myr. Using cloudy evolutionary models, the new companion age range and luminosity result in a mass of 11 M-Jup with a range of 8-15 M-Jup, and an effective temperature of 1040 +/- 50 K.
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Ollander, Sandra. "Fler ekobyar, färre miljöproblem? : More ecovillages, less environmental problems?" Thesis, Malmö universitet, Malmö högskola, Institutionen för Urbana Studier (US), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-18441.
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För att lösa hållbarhetsproblem krävs fokus på mer självförsörjande samhällen som kräver ett lägre behov av konsumtion, energi och transporter då människans nuvarande livsstil och samhällsmål inte går att kombinera med hållbart, klimatvänligt och rättvist. Vår livsstil är dock inte bara orsaken utan även lösningen på hållbarhetsutmaningar. Forskare och medlemmar av gemenskaper menar på att den miljömässigt fördelaktiga livsstil som förknippas med ekobyar och kollektivboenden kan bidra till att uppnå hållbarhetsmål, samt att gemenskaps-baserade initiativ har potential att utgöra en mer hållbar livsstil i jämförelse med konventionella samhällen. En litteraturöversikt och tre intervjuer genomfördes med syftet att undersöka hur ekobyar, som en avsiktlig gemenskap, kan hjälpa oss att leva innanför planetens gränser och vilka sociala utmaningar som ekobyar möter. Resultaten analyserades med hjälp av planetära gränser, donut-ekonomi och nerväxt som en del av emergent normteorin. Studien visar att ekobyar som en avsiktlig gemenskap kan hjälpa oss att leva innanför planetens gränser och bidra till en miljömässigt hållbar utveckling inom sex kategorier: ekologiska system, ekologisk arkitektur, energisystem, transportsystem, matsystem och miljövänligt beteende Sociala utmaningar som upptäcktes i ekobyar är otydliga normer och regler, brist på deltagande och egenemang, ledarskap, beslutsfattande, kommunikation, odelade visioner och mål, ojämn maktbalans, etiska frågor, arbetslöshet, organisering och olika bakgrunder.To solve sustainability problems we need to pay more attention to self sustainable societies with demand for less consumption, energy and transport as our lifestyle can not be combined with sustainability, climate-friendly and fair. Researchers and members of communities believe that the environmentally beneficial lifestyle that is associated with ecovillages and collective housing can contribute to reaching sustainable development goals and a sustainable lifestyle. A literature review and interviews were carried out with the purpose to investigate how ecovillages can help us live within the planetary boundaries and which social challenges ecovillages face. The results showed that ecovillages can help us to live within the planetary boundaries within six categories: ecological systems, ecological architecture, energy systems, transport systems, food systems and environmental friendly behaviour. Social challenges in ecovillages were leadership, decision making, undivided visions and goals, uneven balance of power, ethical questions, unemployment, organisation and different backgrounds.
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Fruth, Thomas [Verfasser], and Heike [Akademischer Betreuer] Rauer. "Search for Planetary Transits and Stellar Variability with BEST II and ASTEP / Thomas Fruth. Betreuer: Heike Rauer." Berlin : Universitätsbibliothek der Technischen Universität Berlin, 2013. http://d-nb.info/1031511466/34.
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Fredrich, Joanne Theresa. "Experimental study of the brittle to plastic transition in marble and diabase." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13752.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1991.Vita.
Includes bibliographical references.
by Joanne Theresa Fredrich.
Ph.D.
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Kelly, Amy E. (Amy Elizabeth) 1980. "Hydrocarbon biomarkers for biotic and environmental evolution through the Neoproterozoic-Cambrian transition." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/52763.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references.
The sequence of events over the Neoproterozoic - Cambrian transition that led to the radiation of multicellular organisms has been an issue of debate for over a century. It is a critical interval in the history of life on Earth because it marks the first appearance of all extant animal phyla in the fossil record. We set out to improve understanding of environmental transitions during this key interval of Earth's history by studying chemical fossils (biomarkers) in Neoproterozoic to Cambrian aged sedimentary rocks and oils from Australia, Eastern Siberia and Oman. This thesis presents the distributions of steranes and other hydrocarbons through these various strata and the characterization of novel age and paleostratification biomarkers. Compound specific carbon isotopic data of n-alkanes and isoprenoids were also acquired and evaluated in the context of existing datasets with a focus on elucidating the processes responsible for anomalous trends. Consistent with current theory, our results indicate that there was a significant shift in the redox state the oceans and that this took place on a global scale. The biomarker and isotopic proxies we have measured help us further constrain the timing of this redox shift, and suggest a concomitant switch in the composition of marine photosynthetic communities, at termination of the Neoproterozoic Era.
by Amy Elizabeth Kelly.
Ph.D.
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Whittaker, Gemma Nicole. "The analysis and removal of systematic trends in STEREO's HI-1A photometry and a search for planetary transits." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/5054/.
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STEREO’s imager, HI-1A, monitors nearly 500,000 stars down to 4th magnitude as it orbits the Sun. The resulting light curves offer unique characteristics and repeatability, which could make significant contributions to stellar variability surveys and the hunt for transiting planets. The HI-1A trend removal pipeline (TRP) was constructed to counteract systematic and observationsal effects and thereby increase the potential of a transit search. This pipeline uses a non-linear iterative filter to provide an adaptable noise-reduction process, without effecting transit-like signals. The TRP reduces the point-to-point scatter by up to 50 % for the brightest targets (R ≤ 6) and 25 % for the faintest (R ≥ 9). The correlated noise on transit timescales was found to be negligible for most targets and only 20 % of the total noise for the brightest stars, which amount to < 3 % of the sample. In an automated search for planet candidates, several transit signals were detected in the HI-1A light curves. Further testing suggests that none of these were veritable planet candidates. However the results show that Neptune-sized planets are certainly detectable and that a more effective reduction of solar-noise will lead to a successful planet search in the future.
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De, Wit Julien. "Maps and masses of transiting exoplanets : towards new insights into atmospheric and interior properties of planets." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/95554.
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Thesis: Ph. D. in Planetary Sciences, Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 183-200).
With over 1800 planets discovered outside of the Solar System in the past two decades, the field of exoplanetology has broadened our perspective on planetary systems. Research priorities are now moving from planet detection to planet characterization. In this context, transiting exoplanets-planets that cross in front of their star from our point-of-view-are of special interest due to the wealth of data made available by their orbital configuration. In this thesis, I introduce two methods, and their Markov chain Monte Carlo implementations, to gain new insights into the atmospheric and interior properties of exoplanets. The first method aims to map an exoplanet's atmosphere based on the eclipse scanning which is obtained while a planet is occulted by its host star. Ultimately temperature, composition, and circulation patterns could be constrained in three-dimensions from these maps, a significant asset for informing atmospheric models. I introduce the basics of eclipse mapping, its caveats (particularly, the correlation between the planet's shape, brightness distribution, and four system parameters), and a framework to mitigate the caveats' effects via global analyses including transits, phase curves, and radial velocity measurements. I use this method to create the first two-dimensional map and the first cloud map of an exoplanet for the hot-Jupiters HD 189733b and Kepler-7b, respectively. The second method, MassSpec, aims to determine transiting planet masses and atmospheric properties solely from transmission spectra, i.e. the starlight filtered by a planet's atmosphere during transits. Determination of an exoplanet's mass is key to understanding its basic properties, including its potential for supporting life. To date, mass constraints for exoplanets are predominantly based on radial velocity measurements, which are not suited for planets with low masses, large semi-major axes, or those orbiting faint or active stars. I demonstrate that a planet's mass has to be accounted for by atmospheric retrieval methods to ensure unbiased estimates of atmospheric properties. Utilizing MassSpec, the James Webb Space Telescope (launch date: 2018) could determine the mass and atmospheric properties of half a dozen Earth-sized planets in their host's habitable zones over its lifetime, which could lead to the first identification of a habitable exoplanet.
by Julien de Wit.
Ph. D. in Planetary Sciences
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Cracchiolo, Gianluca. "Mitigation of the impact of stellar activity on observations of transiting planets." Doctoral thesis, Università degli Studi di Palermo, 2023. https://hdl.handle.net/10447/580043.
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La tesi si concentra sulla quantificazione dell'impatto dell'attività stellare sulle osservazioni dei pianeti in transito e sull'identificazione di una metodologia per correggere questi effetti. In particolare, viene approfondito l'effetto delle macchie stellari, sia non occultate che occulte.
La presenza di macchie sul disco stellare visibile può distorcere la curva della luce di transito primaria in modo dipendente dalla lunghezza d'onda, mimando la presenza di un'atmosfera. Per tener conto di questo effetto, la tesi presenta un metodo innovativo per stimare le proprietà delle macchie e la loro distribuzione dalle osservazioni fuori transito e, su questa base, correggere le curve di luce del transito planetario, evitando possibili degenerazioni tra la presenza di un' atmosfera planetaria e delle macchie. Il metodo è sviluppato per la spettroscopia di transito a bassa risoluzione ed è testato su simulazioni realistiche di future osservazioni di transiti planetari con Ariel, una missione spaziale dedicata all'osservazione di circa 1000 esopianeti in transito il cui lancio è previsto nel 2029. Successivamente, il metodo viene applicato a osservazioni reali di HST di un pianeta in transito. Il primo capitolo della tesi presenta il problema delle macchie stellari sulla spettroscopia a bassa risoluzione e gli sforzi finora compiuti per mitigare il loro effetto sulle osservazioni di pianeti transitanti. Il capitolo 2 presenta un metodo per correggere l'effetto delle macchie non attraversate dal pianeta in transito, partendo da un modello base dell'attività stellare, dove la stella macchiata è simulata come una combinazione lineare di spettri stellari a diverse temperature e la stella ha un emissione uniforme. Il metodo è testato su 3 bersagli simulati di sistemi in transito che saranno osservati dalla missione Ariel. Nel capitolo 3 è introdotto un altro componente nel modello stellare, rendendolo più realistico. Infatti, sono simuli nuovamente gli stessi target analizzati nel Capitolo 2 ma includendo l'effetto di oscuramento al bordo al modello stellare. In questo capitolo è illustrata l'importanza di tener conto di questo effetto se si vuole ottenere una buona stima dei parametri delle macchie e una buona correzione dell'atmosfera del pianeta. Nel Capitolo 4, l'approccio presentato nei capitoli precedenti, e testato su simulazioni, è applicato alle osservazioni dei transiti planetari del pianeta LHS 1140 b, acquisite con il Telescopio Spaziale Hubble. L'analisi porta a due possibili scenari: nel primo la stella è molto attiva e quasi il 65% della sua superficie è ricoperta da macchie (contro altri indicatori in letteratura che suggeriscono una stella tranquilla); nel secondo, la stella è quieta ma è circa 300 K più fredda rispetto al primo scenario. In entrambi i casi, la modulazione cromatica osservata derivata dalle curve di luce di transito planetario non è dovuta alla presenza di un'atmosfera planetaria. Nel Capitolo 5, analizzo le curve di luce TESS della stella attiva V1298 Tau, modellando la stella con un modello a 4 macchie, corotanti con la superficie stellare. Tale studio permette non solo di ricavare la distribuzione delle macchie su V1298 Tau ma anche di correggere le curve di luce di transito dei 4 pianeti orbitanti intorno alla stella per l'effetto delle macchie non occultate. I risultati mostrano che l'effetto delle macchie può produrre differenti profondità di transito per i 4 pianeti in banda TESS e K2, giustificando così la discrepanza tra i raggi planetari nelle due bande riportata nella letteratura scientifica.This thesis focuses on the quantification of the impact of stellar activity on observations of transiting planets and on the identification of a methodology to correct these effects. In particular, the role of starspots, both un-occulted and occulted is considered. The presence of spots on the visible stellar disk may distort the primary transit light curve in a wavelength-dependent way, mimicking the presence of an atmosphere. To take into account this bias, the thesis presents an innovative method to estimate the spots properties and their distribution from the out-of-transit observations and, on this basis, correct the planetary transit light curves, avoiding possible degeneracy between the presence of the planetary atmosphere and of the spots. The method is developed for low-resolution transit spectroscopy and is tested on realistic simulations of future observations of planetary transits with Ariel, a space mission dedicated to the observation of about 1000 transiting exoplanets whose launch is expected in 2029. Then, the method is applied to real observations of HST of a transiting planet. The first chapter of the thesis presents the state of the art of efforts done so far to mitigate the effect of the spots in planetary observations (chapter 1). Chapter 2 presents a method for correcting the effect of spots not-crossed by the transiting planet, starting from a basic model of the stellar activity, where the spotted star is simulated as a linear combination of stellar spectra at different temperatures and the star has a uniform emission. The method is tested on 3 simulated targets of transiting systems that will be observed by the Ariel mission. In Chapter 3, I introduced another component in the stellar model, making it more realistic. In fact, I simulate again the same targets analyzed in Chapter 2 but including the limb darkening effect to the stellar model. In this chapter, I show the importance of taking into account this effect if a good estimate of the spots’ parameters and a good correction of the planet's atmosphere have to be obtained. In Chapter 4 the approach presented in the previous chapters, and tested on simulations, is applied to observations of planetary transits of the planet LHS 1140 b, acquired with the Hubble Space Telescope. The analysis leads to two possible scenarios: in the first one the star is very active and almost the 65% of its surface is covered by spots (against other indicators in the literature suggesting a quiet star); in the second one, the star is quiet but is about 300 K cooler than in the first scenario. In both cases, the observed chromatic modulation derived from the planetary transit light curves is not due to the presence of a planetary atmosphere. In Chapter 5, I analyze the TESS light curves of the active star V1298 Tau, by modeling the star with a model dominated by 4 spots, co-rotating with the stellar surface. Such a study allows not only to derive the distribution of spots on V1298 Tau but also to correct the transit light curves of the 4 planets orbiting around the star for the effect of non-occulted spots. The results show that the spots’ effect may produce different transit depths for the 4 planets in the TESS and the K2 band, thus justifying the discrepancy between the planetary radii in the two bands reported in the scientific literature.
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Neilson, Hilding R., Joseph T. McNeil, Richard Ignace, and John B. Lester. "Limb Darkening and Planetary Transits: Testing Center-to-limb Intensity Variations and Limb-darkening Directly from Model Stellar Atmospheres." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etsu-works/2684.
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The transit method, employed by Microvariability and Oscillation of Stars (MOST), Kepler, and various ground-based surveys has enabled the characterization of extrasolar planets to unprecedented precision. These results are precise enough to begin to measure planet atmosphere composition, planetary oblateness, starspots, and other phenomena at the level of a few hundred parts per million. However, these results depend on our understanding of stellar limb darkening, that is, the intensity distribution across the stellar disk that is sequentially blocked as the planet transits. Typically, stellar limb darkening is assumed to be a simple parameterization with two coefficients that are derived from stellar atmosphere models or fit directly. In this work, we revisit this assumption and compute synthetic planetary-transit light curves directly from model stellar atmosphere center-to-limb intensity variations (CLIVs) using the plane-parallel Atlas and spherically symmetric SAtlas codes. We compare these light curves to those constructed using best-fit limb-darkening parameterizations. We find that adopting parametric stellar limb-darkening laws leads to systematic differences from the more geometrically realistic model stellar atmosphere CLIV of about 50–100 ppm at the transit center and up to 300 ppm at ingress/egress. While these errors are small, they are systematic, and they appear to limit the precision necessary to measure secondary effects. Our results may also have a significant impact on transit spectra.
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Lamm, Rosalee Alicia. "Fine scale imaging of structures at and near the mantle transition zone using a generalized Radon transform." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/37280.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2006.Includes bibliographical references (p. 34-37).
We apply a generalized Radon transform (GRT) to the study of the transition zone discontinuities. The transition zone discontinuities, e.g. the '410' and '660', result from mineral phase changes that occur at depths constrained by temperature and chemistry, and can provide information about the conditions of the mantle within the transition zone. Previous global studies of topography on the transition zone discontinuities use SS data and are limited by the low lateral resolution provided by SS waves, on the order of about 1000 kilometers. The GRT employs inverse scattering theory to image perturbations in mass density and elastic parameters of a medium, and can resolve structure on the order of 100 kilometers; the limit of this resolution has yet to be tested. This study maps discontinuity depths in the northwest Pacific Ocean with a lateral spatial sampling of 1° and a vertical sampling of five kilometers. We observe striking variations in the depth, strength, and continuity of the '410', '520', and '660' seismic discontinuities, as well as the presence of structure beyond the bounds of what is traditionally considered to be the transition zone. Topographies on the '410' and '660' are alternately positively and negatively correlated, suggesting that both composition and temperature contribute to the observed depths. Preliminary analysis of '410' depths, which assumes no variations in chemistry, yields an upper bound for temperature variations of ±280K. Future tests and data preprocessing should further improve the GRT results.
by Rosalee Alicia Lamm.
S.M.
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Pere, Christophe. "Étude de l’atmosphère de Vénus à l’aide d’un modèle de réfraction lors du passage devant le Soleil des 5-6 Juin 2012." Thesis, Université Côte d'Azur (ComUE), 2016. http://www.theses.fr/2016AZUR4063/document.
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Le transit de Vénus devant le Soleil est un événement rare et l’occasion unique pourétudier la réfraction de la lumière du Soleil à travers l’atmosphère, afin de déterminer les propriétésatmosphériques de la planète et en particulier la structure thermique de la haute atmosphère.L'objectif de cette thèse a été la modélisation de cette réfraction lors du passage devant le Soleilqui a eu lieu les 5-6 juin 2012, modèle dont les résultats ont pu être comparés aux données de lamission Venus Express.La première partie est consacrée à l’analyse des images des satellites qui a permis lacréation de courbes de lumière en fonction de la latitude de l’auréole qui serviront de référencepour les modèles. L’étude de l’atmosphère a d’abord été réalisée par une approche isotherme(théorie de Baum et Code,1953). Le modèle a ensuite été affiné en simulant trois couchesisothermes concentriques établies grâce à l’analyse préalable des données SPICAV/SOIR deVenus Express. Pour finir, le dernier modèle développé pour l’étude de l’auréole est un modèlemulticouche concentrique à très haute résolution verticale. Ce modèle a permis d’obtenir un profilvertical de densité en fonction de la latitude, ainsi que l’altitude du tau = 1 (le long de la ligne devisée) induite par les aérosols. Ces données ont ensuite été ensuite utilisées pour générer descartes 2D de température en fonction de la latitude et de l’altitude, que nous comparons auxdonnées d’occultation solaire de la mission Venus Express. Cette étude a également permis dedéterminer de façon indépendante l’échelle de hauteur des aérosols et leur chromaticité dansl’atmosphère de Vénus.Dans un second temps, l’étude de la courbe du transit de 2004 a été menée conjointementavec le Dr. Andréa Chiavassa afin de mettre en évidence l’impact de la granulation stellaire sur lescourbes de transit exoplanétairesThe transit of Venus across the Sun is a rare and unique opportunity to study therefraction of sunlight through the atmosphere, called the "aureola", and determine the atmosphericproperties of the planet and in particular the thermal structure of the upper atmosphere. Theobjective of this thesis was the modeling of this refraction effect at terminator during the passageacross the Sun which took place on June, 5-6 2012, and a comparison with data obtained in thesame region during the Venus Express mission.The first part is devoted to the analysis of data from an Earth-orbiting solar observatory thatallowed the creation of individual aureola light curves according to latitude, that were used as amodeling reference. The study of the refracting atmosphere was first carried out by an isothermalapproach (Baum and Code (1953) theory). The model was then refined by simulating threeconcentric layers based on prior analysis of Venus Express/SPICAV-SOIR vertical density profiledata obtained simultaneously on June 6, 2012. Finally, the complete model developed for thisstudy is a concentric layered model with sub-kilometer vertical resolution. This model has allowedus to retrieve from individual aureole lightcurves a density vertical profile function of the latitudeand the tau = 1 altitude of slanted opacity along the line of sight, induced by mesospheric aerosols.These data were subsequently used to generate temperature maps in 2D function of latitude andaltitude, we compare the solar occultation data from the Venus Express mission (SOIR). This studyalso determined independently the scale height of aerosols and the chromaticity in the atmosphereof Venus.A separate, additional study on 2004 Venus transit data was conducted jointly with Dr.Andrea Chiavassa to highlight the impact of the stellar granulation on exoplanetary transit curves inextrasolar systems
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Burke, Christopher J. "Survey for transiting extrasolar planets in stellar systems stellar and planetary content of the Open Cluster NGC 1245 /." Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1132168623.
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Zellem, Robert Thomas. "Observing Transiting Exoplanets: Removing Systematic Errors To Constrain Atmospheric Chemistry And Dynamics." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/556734.
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The >1500 confirmed exoplanets span a wide range of planetary masses (~1 M_Earth – 20 M_Jupiter), radii (~0.3 R_Earth – 2 R_Jupiter), semi-major axes (~0.005 – 100 AU), orbital periods (~0.3 – 1 x 10⁵ days), and host star spectral types. The effects of a widely-varying parameter space on a planetary atmosphere's chemistry and dynamics can be determined through transiting exoplanet observations. An exoplanet's atmospheric signal, either in absorption or emission, is on the order of ~0.1% which is dwarfed by telescope-specific systematic error sources up to ~60%. This thesis explores some of the major sources of error and their removal from space- and ground-based observations, specifically Spitzer/IRAC single-object photometry, IRTF/SpeX and Palomar/TripleSpec low-resolution single-slit near-infrared spectroscopy, and Kuiper/Mont4k multi-object photometry. The errors include pointing-induced uncertainties, airmass variations, seeing-induced signal loss, telescope jitter, and system variability. They are treated with detector efficiency pixel-mapping, normalization routines, a principal component analysis, binning with the geometric mean in Fourier-space, characterization by a comparison star, repeatability, and stellar monitoring to get within a few times of the photon noise limit. As a result, these observations provide strong measurements of an exoplanet's dynamical day-to-night heat transport, constrain its CH₄ abundance, investigate emission mechanisms, and develop an observing strategy with smaller telescopes. The reduction methods presented here can also be applied to other existing and future platforms to identify and remove systematic errors. Until such sources of uncertainty are characterized with bright systems with large planetary signals for platforms such as the James Webb Space Telescope, for example, one cannot resolve smaller objects with more subtle spectral features, as expected of exo-Earths.
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Lee, Jae Min. "Retrieval of atmospheric structure and composition of exoplanets from transit spectroscopy." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:9daa5af9-040d-47eb-a2ca-57aefcc36f21.
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Recent spectroscopic observations of transiting exoplanets have permitted the derivation of the thermal structure and molecular abundances of H2O, CO, CO2, CH4, metallic oxides and alkali metals in these extreme atmospheres. Here, for the first time, a fully-fledged retrieval algorithm has been applied to exoplanet spectra to determine the thermal structure and composition. The development of a suite of radiative transfer and retrieval tools for exoplanet atmospheres is described, building upon an optimal estimation retrieval algorithm extensively used in solar system studies. Firstly, the collection of molecular line lists and the pre-tabulation of the absorption coefficients (k-distribution tables) for high temperature application are discussed. Secondly, the best-fit spectra for hot Jupiters are demonstrated and discussed case by case. Available sets of primary and secondary transit observations of exoplanets are used to retrieve atmospheric properties from these spectra, quantifying the limits of our knowledge of exoplanetary atmospheres based on the current quality of the data. The contribution functions and the vertical sensitivity to the molecules are fully utilised to interpret these spectra, probing the structure and composition of the atmosphere. Finally, the retrievals provide our best estimates of the thermal and compositional structure to date, using the covariance matrices to properly assess the degeneracy between different parameters and the uncertainties on derived quantities for the first time. This sheds light on the range of diverse interpretations offered by other authors so far, and allows us to scrutinise further atmospheric features by maximising the capability of the current retrieval algorithm and to demonstrate the need for broadband spectroscopy from future missions.
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Zhou, G., G. Á. Bakos, J. D. Hartman, D. W. Latham, G. Torres, W. Bhatti, K. Penev, et al. "HAT-P-67b: An Extremely Low Density Saturn Transiting an F-subgiant Confirmed via Doppler Tomography." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/623926.
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We report the discovery of HAT-P-67b, which is a hot-Saturn transiting a rapidly rotating F-subgiant. HAT-P-67b has a radius of = R-p 2.085(-0.071)(+0.096) R-J, and orbites a M-* = 1.642(-0.072)(+0.155)M(circle dot) , R-* = 2.546(-0.084)(+0.099) R-circle dot host star in a similar to 4.81 day period orbit. We place an upper limit on the mass of the planet via radial velocity measurements to be M-p < 0.59 M-J , and a lower limit of >0.056 M-J by limitations on Roche lobe overflow. Despite being a subgiant, the host star still exhibits relatively rapid rotation, with a projected rotational velocity of vsin I-* = 35.8 +/- 1.1 km s(-1), which makes it difficult to precisely determine the mass of the planet using radial velocities. We validated HAT-P-67b via two Doppler tomographic detections of the planetary transit, which eliminate potential eclipsing binary blend scenarios. The Doppler tomographic observations also confirm that HAT-P-67b has an orbit that is aligned to within 12 degrees, in projection, with the spin of its host star. HAT-P-67b receives strong UV irradiation and is among one of the lowest density planets known, which makes it a good candidate for future UV transit observations in the search for an extended hydrogen exosphere.
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Pepper, Joshua Aaron. "KELT the Kilodegree Extremely Little Telescope /." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1179852674.
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Lyda, Andrew W. "Normal Fault Trace-Length Scaling in a Tectonic Transition Zone in Southern Sedna Planitia, Venus." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1365612940.
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Escobar, David. "Mémoire et édition pendant la transition démocratique espagnole : la collection "Espejo de España" des Editions Planeta de 1973 à 1978." Bordeaux 3, 2008. http://www.theses.fr/2008BOR30044.
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La collection “Espejo de España”, créée en 1973 par le directeur littéraire Rafael Borràs Betriu pour le compte des Editions Planeta, répond à une attente particulière du lectorat de l’époque. Cette collection survient dans le marché éditorial alors que la dictature franquiste vit ses derniers soubresauts et que s’annoncent des changements politiques majeurs. Dans ce contexte, après une dictature dont l’un des soucis fut la préservation d’une mémoire officielle univoque, les volumes de la collection « Espejo de España » apportent des éclairages plus équilibrés sur l’histoire immédiate du pays, ce qui est rendu possible par une censure moins sévère par la force des choses. De ce fait, le lecteur trouve dans ces ouvrages des éléments qui lui permettront de mieux appréhender l’instant historique de la transition démocratique. Cependant, cette collection est l’aboutissement d’un parcours intellectuel que Rafael Borràs débuta au milieu des années cinquante dans le monde du livre. Il créa tout d’abord une revue culturelle à l’esprit ouvert, La Jirafa, puis travailla successivement dans plusieurs maisons d’édition au sein desquelles il affina des projets tournés vers la récupération d’un passé proscrit par la dictature. En outre, l’aboutissement d’ « Espejo de España » ne peut s’entendre que par l’alliance objective de deux dynamiques complémentaires. La collection voit le jour aux éditions Planeta et bénéficie donc de toutes les facilités inhérentes à une maison d’édition prospère économiquement. Qui plus est, cette collection est portée de manière relativement autonome par son directeur Rafael Borràs qui trouve ainsi les moyens de la diffuser à une échelle assez largeThe collection entitled “Espejo de España”, which was created in 1973 by literary director Rafael Borràs Betriu on behalf of Planeta Publishings, came up to the specific expectations of the readership of that time. This collection was issued in the publishing market while the Francoist dictatorship was drawing to a close and major political events were about to emerge. Within this context, in the aftermath of a dictatorship whose main concern had been the preservation of a one-sided official memory, the volumes of the collection “Espejo de España” shed a more balanced light on the immediate history of the country, which was made possible both by a less severe censorship and by force of circumstances. In this respect, these books provide the reader with a real insight into the democratic transition and allow a better grasp of its historical scope. However, this collection is the outcome of an intellectual path initiated by Rafael Borràs in the book world in the middle of the fifties. He first created “La Jirafa”, a cultural review with an open-minded outlook, and then went on to work successively within several publishing houses, which allowed him to refine his projects focused on the recuperation of a past proscribed by the dictatorship. Furthermore, the outcome of “Espejo de España” can only be fully grasped through the objective alliance of two complementary dynamics. The collection came to light in Planeta Publishing and was therefore furthered by a publishing house which was economically prosperous. What is more, this collection was supported in a relatively autonomous way by his director Rafael Borràs who was then able to issue it on a fairly large scale
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Bruno, Giovanni. "Characterization of transiting exoplanets : analyzing the impact of the host star on the planet parameters." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4746/document.
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Dans le cadre de ma thèse, j’ai analysé les spectres de neuf étoiles Kepler obtenus avec les relevés de vitesse radiale (VR). Cela a permis la caractérisation de leur compagnons planétaires. J’ai analysé les spectres de 21 autres étoiles CoRoT et Kepler, probablement hôtes de naines M à faible masse. Cela a permis d’'élargir l'échantillon des étoiles à faible masse avec masse et rayon mesurés. J’ai calculé l’indice d’activité chromosphérique de 31 étoiles observées avec SOPHIE/OHP, en aidant l’étude des interactions étoile-planète. J’ai étudié le comportement de SOPHIE à bas signal à bruit (S/B). J’ai déterminé l’intervalle de S/B dans lequel un spectre stellaire est fiable pour la mesure des paramètres stellaires.Dans le cadre du consortium SOPHIE, j’ai suivi l’analyse complète du système Kepler-117. Ce système multi-planétaire montre variations des périodes orbitaux dues aux échanges dynamiques entre les planètes (TTV). Pour déterminer les paramètres du système, un approche spécifique a été développé pour l’ajustement simultané de transits, VR et TTV (Bruno et al. 2015).Finalement, je me suis intéressé à l’activité stellaire dans la photométrie de transit. J’ai impl ́ementé deux logiciels de modélisation de tâches stellaires dans un code MCMC, en ajoutant l’évolution des tâches dans l’un d’eux. J’ai appliqué les logiciels au Soleil, à CoRoT-7 et à CoRoT-2. J’ai amené un étude détaillé de la courbe de lumière de CoRoT-2, et exploré les effets des tâches dans les paramètres du transit (Bruno et al., en prep.). Avec la méthode FF’ (Aigrain et al. 2012), j’ai contribué à l’exploration du lien entre la signature des tâches de CoRoT-7 et dans la photométrie et dans les VRDuring my PhD, I analyzed the spectra of nine Kepler stars obtained by radial velocity (RV) observations. This allowed the characterization of their planetary companions. I analyzed the spectra of twenty-one other CoRoT and Kepler stars, likely orbited by low-mass M dwarfs. This helped widening the sample of low-mass stars with measured mass and radius. I calculated the chromospheric activity indfex of thirty-one stars observed with SOPHIE/OHP, helping the study of star-planet interactions. I studied the behavior of SOPHIE in low signal-to-noise ratio (SNR) regime. I determinhed the SNR range in which a stellar spectrum is reliable for the measure of the stellar parameters.Within the SOPHIE consortium, I followed the complete analysis of the Kepler-117 system. This multi-planetary system presents variations in the planetary orbital periods due to their mutual dynamical interacion (TTVs). To fit the system parameters, a specific fitting approach including TTV modeling was developed. We derived the system parameters by the simultaneous fit of transits, RVs, and TTVs (Bruno et al. 2015).Finally, I addressed the problem of stellar activity in transit photometry. I implemented two starspot modeling codes into an MCMC algorithm, adding spot evolution to oneof them. I applied the codes to the Sun, CoRoT-7, and CoRoT-2. I carried an extensive study on the light curve of CoRoT-2, and explored the effects of the spots on the transit parameters (Bruno et al., in prep.). With the FF’ method (Aigrain et al. 2012), I contributed to explore the connection between the photometric and RV signature of starspots in CoRoT-7
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Fogliardi, Michele. "Proprietà generali dei pianeti del sistema solare e ricerca di pianeti esterni." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21236/.
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In questo elaborato vengono analizzate le principali proprietà fisiche, chimiche e strutturali dei pianeti del Sistema Solare, soffermandosi in particolar modo sulle differenze esistenti tra i pianeti di tipo terrestre e quelli di tipo gioviano, ovvero tra i pianeti rocciosi e i giganti gassosi. In seguito vengono descritte le principali tecniche di ricerca dei pianeti extrasolari, discernendo tra metodi diretti e indiretti. In particolare, dopo una breve descrizione dell'origine del sistema solare secondo la teoria nebulare, ovvero quella attualmente più accreditata, si passa ad una caratterizzazione delle atmosfere planetarie e del meccanismo alla base delle differenze di composizione chimica tra le due tipologie di pianeti, a cui segue una descrizione delle loro proprietà generali. Infine, vengono messi in evidenza i principali metodi di ricerca e di individuazione dei pianeti extrasolari, soffermandosi in particolar modo sui metodi indiretti, quali il metodo delle velocità radiali, il metodo dei transiti, il metodo astrometrico e il microlensing gravitazionale.
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Michel, Nathalie. "Modélisation de l'évolution thermique de Mars : conséquences sur le champ magnétique." Phd thesis, Université Paul Sabatier - Toulouse III, 2011. http://tel.archives-ouvertes.fr/tel-00572876.
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Actuellement, Mars n'a pas de champ magnétique global comme la Terre mais les traces d'aimantations rémanentes dans la croûte Martienne, révélées par Mars Global Surveyor dès 1998, montrent qu'un champ magnétique était présent dans le passé, et que celui-ci a disparu il y a environ 4 milliards d'années. Cependant, les travaux de Lillis et al. (2006) suggèrent que la dynamo dans le noyau, qui permet la présence d'un tel champ magnétique, a pu connaître un second épisode d'activité pendant une brève période, quelques centaines de millions d'années après la disparition du champ magnétique initial. C'est la compréhension des conditions de disparition et éventuellement de réapparition du champ magnétique qui a motivé mon travail de thèse. La présence d'un champ magnétique est liée à l'activité du noyau de la planète, et au transfert de la chaleur dans le manteau. C'est pourquoi ma thèse concerne l'étude de la dynamique interne, à l'aide du code de simulations numériques CITCOM2D. Ce code, initialement conçu pour l'étude du manteau terrestre, a été modifié et adapté pour le cas Martien, notamment pour prendre en compte le refroidissement du noyau et la présence de transitions de phase haute pression des silicates. La transition de phase endothermique spinelle-perovskite, tend à inhiber la convection. Sa profondeur peut augmenter avec le refroidissement du noyau, jusqu'à ce que la transition disparaisse et libère rapidement la chaleur, entraînant éventuellement une réactivation de la dynamo du noyau. Les incertitudes sur la taille du noyau de la planète, mais aussi la composition du manteau, m'ont amené à étudier la dynamique interne à l'aide de plusieurs modèles. Les résultats montrent qu'une réactivation du noyau est possible, mais qu'elle n'est pas liée à la présence d'une couche de perovskite proche du noyau. En effet, un manteau initialement froid et non convectif, ainsi qu'une viscosité peu dépendante de la température, permettent d'obtenir une réactivation du noyau vers 1 milliard d'années, lorsque la convection démarre dans le manteau. Dans des conditions de températures plus élevées, cette réactivation n'est pas possible car la convection démarre très vite. Cependant la transition spinelle-perovskite a des effets non négligeables puisqu'elle tend à réchauffer le noyau et le manteau. De plus, dans ces conditions, l'ajout d'un saut de viscosité entraîne rapidement une situation instable et un phénomène d'avalanche où un panache chaud ascendant se forme et permet au noyau de refroidir efficacement. En conclusion, les conditions initiales de température et la loi de viscosité s'avèrent des paramètres capitaux quant à l'évolution thermique de la planète.
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Bordé, Pascal. "Recherche des exoplanètes, mesure de leurs propriétés physiques et orbitales." Habilitation à diriger des recherches, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00917762.
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L'exoplanétologie est une science jeune qui n'a véritablement démarré qu'en 1995 avec la découverte d'une exoplanète géante en orbite rapprochée autour de l'étoile solaire 51 Pegasi. Mes premières recherches dans de domaine datent de 1999 et concernent la mission spatiale Corot qui a conduit depuis 2006 à la détection de plus d'une trentaine de nouvelles exoplanètes très diverses. J'ai pleinement participé à l'aventure de Corot, en commençant par l'estimation du nombre de planètes détectables de 1999 à 2003, en poursuivant par la recherche et la caractérisation des signaux d'éclipses partielles, ou transits, lorsque les données furent disponibles à partir de 2007, pour finir par la mesure des propriétés physiques et orbitales des exoplanètes détectées, notamment Corot-7b en 2009, la première exoplanète rocheuse au rayon et à la masse mesurés, et Corot-8b en 2010, un mini-saturne dense. Je travaille actuellement au calcul de la probabilité de la nature planétaire de tous les signaux de transits détectés par la mission. Mes autres travaux de recherche concernent deux techniques de haute résolution angulaire pour la détection directe d'exoplanètes : l'interférométrie à longue base dans l'infrarouge et la coronographie dans le visible. En interférométrie, j'ai contribué à la précision de l'étalonnage des instruments en compilant deux catalogues d'étoiles-étalons, j'ai mesuré les propriétés d'un prototype de fibre monomode dans l'infrarouge moyen, et j'ai observé des étoiles naines, géantes et doubles. Mon résultat majeur est la détection directe du compagnon faible de l'étoile Theta Draconis. Enfin, en coronographie, j'ai développé en 2006 une méthode de correction de tavelures à l'aide d'un miroir déformable dans le cadre du projet Terrestrial Planet Finder Coronagraph de la Nasa. En cas de sélection du projet Echo par l'Esa en février 2014, mes recherches futures pourraient concerner la spectrométrie par transmission de l'atmosphère d'exoplanètes à courte période.
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Sandford, Emily Ruth. "The Shapes of Planet Transits and Planetary Systems." Thesis, 2020. https://doi.org/10.7916/d8-jqt7-9a41.
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In this Thesis, I explore transiting exoplanets: what we can learn from modeling their light curves, and what we can learn from their arrangement in planetary systems. I begin in Chapter 1 by briefly reviewing the history of transit modeling, from the earliest theoretical models of eclipsing binary stars to the models in current widespread use to model exoplanet transits. In Chapter 2, I model the transits of a sample of Kepler exoplanets with strong prior eccentricity constraints in order to derive correspondingly strong constraints on the density of their host stars, and find that the density constraints I derive are as precise as density constraints from asteroseismology if the transits are observed at high signal-to-noise. In Chapter 3, I apply the same methodology in reverse: using prior knowledge of the stellar density based on Gaia parallax measurements, I model the transits of twelve singly-transiting planets observed by K2 and derive constraints on their periods. In Chapter 4, I consider the general problem of deducing the shape of a transiting object from its light curve alone, which I term ``shadow imaging;'' I explore the mathematical degeneracies of the problem and construct shadow images to explain Dips 5 and 8 of Boyajian's Star.
I next turn to multi-planet systems: in Chapter 5, I investigate the underlying multiplicity distribution of planetary systems orbiting FGK dwarfs observed by Kepler. I find that we can explain the multiplicities of these systems with a single Zipfian multiplicity distribution, without invoking a dichotomous population. In Chapter 6, I consider the arrangement of planets in those systems, and use neural networks inspired by models used for part-of-speech tagging in computational linguistics to model the relationship between exoplanets and their surrounding "context," i.e. their host star and sibling planets. I find that our trained regression model is able to predict the period and radius of an exoplanet to a factor of two better than a naive model which only takes into account basic dynamical stability. I also find that our trained classification model identifies consistent classes of planets in the period-radius plane, and that it is rare for multi-planet systems to contain a neighboring pair of planets from non-contiguous classes.
In Chapter 7, I summarize these results and briefly discuss avenues for future work, including the application of our methods to planets and planetary systems discovered by TESS.
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Lin, Yi-Ling, and 林怡伶. "The Observations and Analysis of Transit Events In the XO-1 Planetary System." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/57166637360335136176.
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碩士國立清華大學
天文研究所
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We observed two newly transits of the XO-1 planetary system. The observations of one of these transit events are done by using the 46-cm telescope hosted by Wise Observatory in Israel. The observations of the other one are done by using both 104-cm and 130-cm telescopes located at ARIES in India. We investigate the possibility for the transit timing variations (TTVs) in the orbital period of XO-1b that may aroused by the existents of an additional planet in this system, so we collected 28 transits from public data and analyzed with our own data. After the O-C diagram of the XO-1 system is obtained and analyzed, we found that a null TTV produces a fit with χred2=2.1764. We also find that the ephemeris with a sinusoidal function of a frequency 0.483985 has a fit with χred2=1.7962 and the one of a frequency 0.10706 has a fit with χred2=2.0867.
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Johnson, Marshall Caleb. "Doppler tomographic observations of exoplanetary transits." 2013. http://hdl.handle.net/2152/21310.
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Transiting planet candidates around rapidly rotating stars, a number of which have been found by the Kepler mission, are not amenable to follow-up via the usual radial velocity techniques due to their rotationally broadened stellar lines. An alternative method is Doppler tomography. In this method, the distortions of the stellar spectral lines due to subtracted light during the transit are spectroscopically resolved. This allows us to not only validate the transiting planet candidate but also to obtain the spin-orbit misalignment for the system. The spin-orbit misalignment is a powerful statistical tracer of the migration histories of planets. I discuss our project to perform Doppler tomographic observations of Kepler candidates and other transiting planets using the facilities at McDonald Observatory. I present our first transit detection, that of Kepler-13 b, and discuss some other recent results.text
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Molinié, Roxana. "Experiencia de la desaparición en Lumpérica de Diamela Eltit, Los planetas de Sergio Chejfec y Los rubios de Albertina Carri." Thèse, 2014. http://hdl.handle.net/1866/12018.
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Cette thèse analyse l’articulation de l’expérience de la perte d’expérience à laquelle donnent lieu les dictatures et les post-dictatures au Chili et en Argentine dans Lumpérica (1983) de Diamela Eltit, Los planetas (1999) de Sergio Chejfec, et Los rubios (2003) d’Albertina Carri. Les dernières dictatures militaires dans le Cône sud latino-américain imposent ou préparent le terrain pour l’implantation d’un nouvel ordre néolibéral qui s’intensifie sous les régimes démocratiques postérieurs. Au cours de cette transition, le terrorisme d’État au moyen duquel les gouvernements militaires visent à éliminer toute forme de résistance à la reconfiguration de la société nécessaire à la mise en place de politiques néolibérales, donne lieu à une expérience inédite, difficile à communiquer. De plus, autant les dictatures que les démocraties post-dictatoriales mettent en oeuvre des mécanismes d’oubli du passé, soit par la répression, le consensus politique ou les moyens de communication de masse. C’est dans ce contexte que l’expérience disparaît.
Le questionnement sur l’expérience de la perte d’expérience est basé principalement sur deux axes théoriques: le concept de transition de l’État au Marché dans le Cône sud latino-américain développé par des intellectuels tels que Willy Thayer, Idelber Avelar ou Brett Levinson, parmi d’autres, ainsi que sur les réflexions sur l’expérience dictatoriale de Sergio Rojas et sur la crise de l’expérience dans la modernité de Walter Benjamin.
Le premier chapitre, dédié à Lumpérica, interprète le rituel nocturne où la protagoniste, une femme appelée L. Iluminada, séduit le protagoniste masculin du roman, un panneau électrique appelé “el luminoso” qui projette des messages publicitaires au milieu d’une place publique de Santiago, pour que celui-ci la blesse et marque sa peau, comme la mise en scène d’un “désir photographique” de garder une empreinte de la transition que d’autres moyens de communication tendent à effacer. Le deuxième chapitre traite de la figuration de l’excès dans Los planetas et analyse comment l’écriture, la photographie et l’espace urbain, en assumant une fonction de suppléments de la voix et de la présence de M, séquestré et disparu pendant la dictature argentine, rendent compte de l’expérience de la perte de l’expérience d’une plénitude. Après avoir exposé le rôle des jouets dans la polémique générée par Los rubios, le troisième chapitre analyse comment le film de Carri sur la mémoire de ses parents disparus transmet l’expérience des générations post-dictatoriales et fait face à l’héritage du passé par le jeu.This thesis analyzes how Diamela Eltit’s Lumpérica (1983), Sergio Chejfec’s Los planetas (1999), and Albertina Carri’s Los rubios (2003) articulate the experience of the loss of experience resulting from the dictatorships and post-dictatorships in Chile and Argentina. The last military dictatorships in the Southern Cone either impose or prepare the ground for the establishment of a new neoliberal order that deepens and intensifies with later democratic regimes. In this transition, the military governments deploy strategies of State terrorism that aim to eliminate all forms of resistance to the social reconfiguration necessary for the implementation of neoliberal politics, giving rise to an unprecedented kind of experience that is difficult to communicate. Moreover, both the dictatorships and the post-dictatorial democracies adopt strategies of forgetting, through either repression, political consensus or mass media communications. It is in this context that experience disappears. The discussion on experience of the loss of experience is based mainly on the concept of transition from State to Market in Latin America’s Southern Cone developed by thinkers such as Willy Thayer, Idelber Avelar or Brett Levinson, among others, as well as on Sergio Rojas’s considerations on dictatorial experience and on Walter Benjamin’s reflections on the crisis of experience in modern life. The first chapter, dedicated to Lumpérica, analyzes a nocturnal ritual where the protagonist, a woman named L. Iluminada, seduces the male protagonist, an electric billboard called “el luminoso” that projects publicity messages in the middle of a public square in Santiago; she hopes to make him wound and mark her skin, staging a “photographic desire” to keep a trace of the transition that other media push towards forgetting and erasure. The second chapter focuses on the figuration of excess in Los planetas, analyzing how writing, photography and urban space act as supplements to the voice and to the presence of M, a young man who disappeared during the Argentinian dictatorship, thus accounting for the loss of experience. After revisiting the debate incited by Los rubios, much of which centred on the film’s polemic use of toys, the third chapter analyzes how Carri’s film about the memory of her disappeared parents transmits the experience of post-dictatorial generations and confronts the heritage of the past through play.
En esta tesis se analiza la articulación de la experiencia de la pérdida de experiencia a la que dan lugar las dictaduras y las postdictaduras en Chile y Argentina, en Lumpérica (1983) de Diamela Eltit, Los planetas (1999) de Sergio Chejfec, y Los rubios (2003) de Albertina Carri. Las últimas dictaduras militares en el Cono Sur imponen o preparan el terreno para la implantación de un nuevo orden neoliberal que se intensifica durante los regímenes democráticos posteriores. En esta transición, el terrorismo de Estado mediante el cual los gobiernos militares buscan eliminar toda forma de resistencia a la reconfiguración de la sociedad que requiere la implementación de las políticas neoliberales, da lugar a una experiencia inédita, difícil de comunicar. Por otro lado, tanto las dictaduras como las democracias postdictatoriales ponen en marcha mecanismos de olvido del pasado, ya sea mediante la represión, el consenso político o los medios de comunicación de masas. Es en este contexto que la experiencia desaparece. Las premisas teóricas en que se basa el cuestionamiento sobre la experiencia de la pérdida de experiencia son el concepto de transición del Estado al Mercado en el Cono Sur latinoamericano desarrollado por intelectuales como Willy Thayer, Idelber Avelar o Brett Levinson, entre otros, así como las reflexiones sobre la experiencia dictatorial de Sergio Rojas y sobre la crisis de la experiencia en la modernidad de Walter Benjamin. El primer capítulo, dedicado a Lumpérica, interpreta el ritual nocturno en el que la protagonista, una mujer llamada L. Iluminada, seduce al protagonista masculino de la novela, un cartel eléctrico llamado “el luminoso” que proyecta avisos comerciales en el centro de una plaza de Santiago, para que este la hiera y marque su piel, como la puesta en escena de un “deseo fotográfico” de guardar una huella de la transición que otros medios tienden a borrar. El segundo capítulo enfoca la figuración del exceso en Los planetas y analiza cómo la escritura, la fotografía y el espacio urbano, al adquirir en la novela una función de suplementos de la palabra viva y de la presencia de M, secuestrado y desaparecido durante la dictadura argentina, dan cuenta de la experiencia de la pérdida de la experiencia de una plenitud. Después de exponer el rol de los juguetes en la polémica generada por Los rubios, el tercer capítulo analiza cómo el film de Carri sobre la memoria de sus padres montoneros desaparecidos transmite la experiencia de las generaciones postdictatoriales y se enfrenta al legado del pasado mediante el juego.
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Petrucci, Romina Paola. "Estudio de variaciones en los tiempos de mínimo en estrellas con planetas transitantes del Hemisferio Sur." Doctoral thesis, 2015. http://hdl.handle.net/11086/2868.
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Tesis (Doctor en Astronomía)--Universidad Nacional de Córdoba, Facultad de Matemática, Astronomía y Física, 2015.En este trabajo presentamos los resultados del monitoreo y análisis homogéneo de tránsitos de planetas que orbitan alrededor de estrellas del Hemisferio Sur. El propósito principal de este seguimiento fotométrico es el de buscar variaciones en los tiempos de mínimo (TTVs) que pudieran atribuirse a la presencia de otros cuerpos de masa planetaria no detectados, ligados gravitacionalmente al sistema. Para ello realizamos observaciones con los telescopios argentinos Horacio Ghielmetti (THG) de 40 cm localizado en el Complejo Astronómico El Leoncito (CASLEO) y el telescopio de 1.54 m ubicado en la Estación Astrofísica de Bosque Alegre (EABA). Dado que se requieren muchos datos para llevar a cabo análisis de TTVs confiables, sólo estudiamos las 3 estrellas de nuestra muestra inicial que presentaron más de 10 observaciones entre propias y extraídas de la literatura. Como subproducto del análisis de variaciones en los tiempos de mínimo, para cada uno de nuestros objetos computamos nuevas efemérides y re-determinamos los parámetros físicos de la estrella y el planeta. Considerando que los puntos analizados comprenden como mínimo 3 años de observaciones, además de estudiar las variaciones a largo plazo de los tiempos de mínimo, evaluamos las variaciones en la inclinación de la órbita (i) y la profundidad del tránsito (k) que también pudieran atribuirse a la presencia de otro cuerpo de masa planetaria en el sistema.
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Шмиков, Євген Олегович. "Удосконалення конструкції планетарного приводу кривошипного пресу." Магістерська робота, 2020. https://dspace.znu.edu.ua/jspui/handle/12345/2733.
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Шмиков Є. О. Удосконалення конструкції планетарного приводу кривошипного пресу : кваліфікаційна робота магістра спеціальності 133 "Галузеве машинобудування" / наук. керівник Т. О. Васильченко. Запоріжжя : ЗНУ, 2020. 103 с.UA : В роботі обґрунтовано переваги використання приводу, встановлені основні закономірності руху ланок в період вмикання та зупинки, визначені навантаження на них та витрати енергії. Використання привода забезпечує зниження загальної ваги преса, усувається проміжна передача в багатоступеневому приводі, знижуються витрати роботи на вмикання порівнюючи з фрикційними муфтами.
EN : The work substantiates the advantages of using a drive, establishes the basic laws of link movement during the start and stop periods, certain loads on them and energy consumption. The use of the drive reduces the total weight of the press, eliminates the intermediate gear in a multi-stage drive, reduces the cost of the work on the inclusion compared with friction clutches.