Готові списки джерел за темами / Low mass companions

Добірка наукової літератури з теми "Low mass companions"

Автор: Grafiati
Опубліковано: 4 травня 2024

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Статті в журналах з теми "Low mass companions"

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Evans, Nancy Remage, Scott Engle, Ignazio Pillitteri, Edward Guinan, H. Moritz Günther, Scott Wolk, Hilding Neilson, et al. "X-Rays in Cepheids: Identifying Low-mass Companions of Intermediate-mass Stars*." Astrophysical Journal 938, no. 2 (October 1, 2022): 153. http://dx.doi.org/10.3847/1538-4357/ac6fdf.

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Abstract X-ray observations have been made of a sample of 20 classical Cepheids, including two new observations (Polaris and l Car) reported here. The occurrence of X-ray flux around the pulsation cycle is discussed. Three Cepheids are detected (δ Cep, β Dor, and Polaris). X-rays have also been detected from the low-mass F, G, and K companions of four Cepheids (V473 Lyr, R Cru, V659 Cen, and W Sgr) and one hot companion (S Mus). Upper limits on the X-ray flux of the remaining Cepheids provide an estimate that 28% have low-mass companions. This fraction of low-mass companions in intermediate-mass Cepheids is significantly lower than expected from random pairing with the field initial mass function (IMF). Combining the companion fraction from X-rays with that from ultraviolet observations results in a binary/multiple fraction of 57% ± 12% for Cepheids with ratios q > 0.1 and separations a >1 au. This is a lower limit since M stars are not included. X-ray observations detect less massive companions than other existing studies of intermediate-mass stars. Our measured occurrence rate of unresolved, low-mass companions to Cepheids suggests that intermediate-period binaries derive from a combination of disk and core fragmentation and accretion. This yields a hybrid mass ratio distribution that is skewed toward small values compared to a uniform distribution but is still top-heavy compared to random pairings drawn from the IMF.
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2

Scott Gaudi, B. "Microlensing Constraints on Low-Mass Companions." Symposium - International Astronomical Union 211 (2003): 305–8. http://dx.doi.org/10.1017/s0074180900210826.

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Microlensing is sensitive to binary, brown dwarf (BD), and planetary companions to normal stars in the Galactic bulge with separations between about 1–10 AU. The accurate, densely-sampled photometry of microlensing events needed to detect planetary companions has been achieved by several follow-up collaborations. Detailed analysis of microlensing events toward the bulge demonstrates that less than 45% of M-dwarfs in the bulge have MJup companions between 1 and 5 AU. Detection of binary and BD companions using microlensing is considerably easier; however, the interpretation is hampered by their non-perturbative influence on the parent lightcurve. I demonstrate that ~ 25% of BD companions with separations 1 – 10AU should be detectable with survey-quality data (~ 1 day sampling and ~ 5% photometry). Survey data is more amenable to generic, brute-force analysis methods and less prone to selection biases. An analysis of the ~ 1500 microlensing events detected by OGLE-III in the next three years should test whether the BD desert exists at separations 1 – 10AU from M-dwarfs in the Galactic bulge.
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3

Naef, D., M. Mayor, D. Queloz, S. Udry, F. Arenou, J. L. Beuzit, C. Perrier-Bellet, and J. P. Sivan. "ELODIE low-mass companions to solar-type stars." Symposium - International Astronomical Union 202 (2004): 96–98. http://dx.doi.org/10.1017/s0074180900217580.

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We present radial-velocity measurements for three solar-type stars (HD 127506, HD 174457 and HD 185414) hosting low-mass companions. The measurements were obtained with the ELODIE echelle spectrograph mounted on the 1.93–m telescope at Observatoire de Haute–Provence (CNRS, France) within the frame of the OHP-ELODIE Planet Search Programme. The inferred minimum masses of the detected companions are in the substellar mass range. Combining ELODIE radial-velocity data and HIPPARCOS astrometric data, the inclination angles of the orbital planes of HD 127506 and HD 174457 have been derived providing us with the de-projected masses of the companions: m2 = 44MJup for the companion of HD 127506 and m2= 0.13M⊙ for the companion of HD 174457. Moreover, using adaptive optics measurements, we show that HD 174457 is probably a (F8V + M7V + M3-4V) triple system. To date, only a minimal orbital solution is available for HD 185414.
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4

Guenther, E. W., D. B. Paulson, W. D. Cochran, J. Patience, A. P. Hatzes, and B. Macintosh. "Low-mass companions to Hyades stars." Astronomy & Astrophysics 442, no. 3 (October 14, 2005): 1031–39. http://dx.doi.org/10.1051/0004-6361:20052851.

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5

Farihi, J., B. Zuckerman, and E. E. Becklin. "Low mass companions to white dwarfs." Astronomische Nachrichten 326, no. 10 (December 2005): 964–68. http://dx.doi.org/10.1002/asna.200510434.

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6

Ginzburg, Sivan, and Eliot Quataert. "Black widow formation by pulsar irradiation and sustained magnetic braking." Monthly Notices of the Royal Astronomical Society 500, no. 2 (October 29, 2020): 1592–603. http://dx.doi.org/10.1093/mnras/staa3358.

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ABSTRACT Black widows are millisecond pulsars with low-mass companions, a few per cent the mass of the sun, on orbits of several hours. These companions are presumably the remnants of main-sequence stars that lost their mass through a combination of Roche lobe overflow and ablation by the host pulsar’s high-energy radiation. While ablation itself is too weak to significantly reduce the mass of the companion star, the ablated wind couples to its magnetic field, removes orbital angular momentum, and thus maintains stable Roche lobe overflow. We use the mesa stellar evolution code, complemented by analytical estimates, to track initially main-sequence companions as they are reduced to a fraction of their original mass by this ablation-driven magnetic braking. We argue that magnetic braking remains effective even for low-mass companions. A key ingredient of our model is that the irradiating luminosity of the pulsar Lirr deposits energy in the companion’s atmosphere and thereby slows down its Kelvin–Helmholtz cooling. We find that the high-energy luminosities measured by Fermi $L_{\rm irr}=0.1\rm {-}3$ L⊙ can explain the span of black widow orbital periods. The same Lirr range reproduces the companions’ night-side temperatures, which cluster around 3000 K, as inferred from optical light curves.
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Jódar, Esther, Antonio Pérez-Garrido, Anastasio Díaz-Sánchez, Isidro Villó, Rafael Rebolo, and Jorge A. Pérez-Prieto. "New companions to nearby low-mass stars." Monthly Notices of the Royal Astronomical Society 429, no. 1 (December 10, 2012): 859–67. http://dx.doi.org/10.1093/mnras/sts382.

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8

Wolf, M., P. Zasche, H. Kučáková, J. Vraštil, K. Hornoch, L. Šmelcer, F. Bílek, L. Pilarčík, and M. Chrastina. "Substellar companions in low-mass eclipsing binaries." Astronomy & Astrophysics 587 (February 22, 2016): A82. http://dx.doi.org/10.1051/0004-6361/201527941.

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Andrews, Jeff J., Adrian M. Price-Whelan, and Marcel A. Agüeros. "THE MASS DISTRIBUTION OF COMPANIONS TO LOW-MASS WHITE DWARFS." Astrophysical Journal 797, no. 2 (December 9, 2014): L32. http://dx.doi.org/10.1088/2041-8205/797/2/l32.

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Zhou, Yifan, Gregory J. Herczeg, Adam L. Kraus, Stanimir Metchev, and Kelle L. Cruz. "ACCRETION ONTO PLANETARY MASS COMPANIONS OF LOW-MASS YOUNG STARS." Astrophysical Journal 783, no. 1 (February 18, 2014): L17. http://dx.doi.org/10.1088/2041-8205/783/1/l17.

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Дисертації з теми "Low mass companions"

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Stone, Jordan M., Josh Eisner, Andy Skemer, Katie M. Morzinski, Laird Close, Jared Males, Timothy J. Rodigas, Phil Hinz, and Alfio Puglisi. "L-BAND SPECTROSCOPY WITH MAGELLAN-AO/Clio2: FIRST RESULTS ON YOUNG LOW-MASS COMPANIONS." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621975.

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L-band spectroscopy is a powerful probe of cool low-gravity atmospheres: the P, Q, and R branch fundamental transitions of methane near 3.3 mu m provide a sensitive probe of carbon chemistry; cloud thickness modifies the spectral slope across the band; and H-3(+) opacity can be used to detect aurorae. Many directly imaged gas-giant companions to nearby young stars exhibit L-band fluxes distinct from the field population of brown dwarfs at the same effective temperature. Here we describe commissioning the L-band spectroscopic mode of Clio2, the 1-5 mu m instrument behind the Magellan adaptive-optics system. We use this system to measure L-band spectra of directly imaged companions. Our spectra are generally consistent with the parameters derived from previous near-infrared spectra for these late M to early L type objects. Therefore, deviations from the field sequence are constrained to occur below 1500 K. This range includes the L-T transition for field objects and suggests that observed discrepancies are due to differences in cloud structure and CO/CH4 chemistry.
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Santos, Leonardo Augusto Gonçalves dos. "The rotational evolution of Sun-like stars and the influence of low-mass binary companions." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/14/14131/tde-22052018-174015/.

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The Solar Twin Planet Search program is an unprecedented eort that aimed to procure extrasolar planets in more than 70 stars extremely similar to the Sun. In the course of this program, hundreds of high-quality optical spectra were obtained for these stars using the HARPS spectrograph, which is fed by the ESO La Silla 3.6 m telescope. Beyond the search for exoplanets, the data are invaluable to study the physical properties of Sun-like stars. Particularly in this dissertation, we are interested in verifying if the Sun possesses a regular rotation for its age among stars that are strictly similar to it, how the rotation of solar twins evolve with age and if the rotation of Sun-like stars is influenced by the presence of stellar mass companions. Previous conclusions on the regularity of the Suns rotation have been conflicting, and this is the first time such a large sample of solar twins with high quality spectroscopic data is used to clarify this puzzle. Our results suggest that the Sun is indeed a regular rotator for its age, which favors the use of the solar rotation to calibrate gyrochronology -- the estimation of stellar ages from their rotation. However, these results also imply a rotational evolution process that saturates after the solar age, constituting a departure from the widely used Skumanich relation and posing a challenge for gyrochronology. We securely identified 18 binary or multiple systems in the solar twin sample, of which only three display enhanced rotation for their ages. I estimated the orbital parameters of the binaries from their radial velocity variations, and the results show that their spectroscopic companions lie at orbital periods varying from a few to several years. I conclude that the presence of red or brown dwarf companions at moderate to long orbital periods do not influence the evolution of rotation in these systems, and therefore the main stars should evolve as single in this regard. The peculiarities in HIP 19911, HIP 67620 and HIP 103983 can be fully explained by spectral contamination from their companions.
O programa The Solar Twin Planet Search é um esforço sem precedentes na procura de planetas extra-solares em mais de 70 estrelas extremamente similares ao Sol. Ao longo desse programa, centenas de espectros ópticos de alta qualidade foram obtidos com o espectrógrafo HARPS, que está instalado no telescópio de 3,6 m do Observatório de La Silla. Além da busca de exoplanetas, estes dados são úteis para estudar as propriedades físicas de estrelas como o Sol. Estamos interessados em verificar se o Sol possui uma rotação regular para sua idade quando comparado com estrelas estritamente similares a ele, como que a rotação de gêmeas solares evolui com o tempo e se a rotação dessas estrelas é influenciada pela presença de companheiras estelares. Conclusões anteriores na regularidade da rotação solar são conflitantes, e esta é a primeira vez que uma amostra grande de gêmeas solares com dados espectroscópicos de alta qualidade é usada para esclarecer essa questão. Nossos resultados sugerem que o Sol de fato rota regularmente para sua idade, o que favorece o uso da rotação solar para calibrar a girocronologia -- a estimativa de idades estelares a partir de sua rotação. No entanto, tais resultados também implicam em um processo de evolução rotacional que satura depois da idade solar, constituindo um desvio da amplamente usada relação de Skumanich e apresentando um desafio para a girocronologia. Nós identificamos 18 sistemas binários na amostra de gêmeas solares, das quais apenas três mostram rotações elevadas para suas idades. Os parâmetros orbitais das binárias foram estimados a partir da variação de suas velocidades radiais, e os resultados mostram que suas companheiras espectroscópicas possuem períodos orbitais variando de alguns poucos até muitos anos. Concluimos que a presença de companheiras do tipo anãs vermelhas ou marrons em períodos orbitais moderados não influenciam a evolução rotacional desses sistemas. As peculiaridades de HIP 19911, HIP 67620 e HIP 103983 podem ser completamente explicadas por contaminação espectral de suas companheiras.
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3

Henry, Todd Jackson. "A systematic search for low-mass companions orbiting nearby stars and the calibration of the end of the stellar main sequence." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185689.

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We have completed a search for low luminosity companions, including high mass brown dwarfs, to all M dwarfs known within eight parsecs of the sun, and north of -25°. We found six new companions orbiting the survey stars. The masses of the six new secondaries fall between 0.39 and 0.05 M(⊙). Three of the new companions, G208-44B, GL 623B and LHS 1047B, and one previously known secondary in the survey, Ross 614B, are brown dwarf candidates with masses ∼80 Jupiters (0.08 M(⊙)), the dividing line between stars and brown dwarfs. In addition, we provide infrared photometry at J, H and K for all 99 survey members, and spectral types on standard system for half. Analysis of the entire sample indicates that 50% of the stars in the more distant half of the survey volume remain undetected, as is supported by the steadily growing M dwarf census over the last 45 years. The binary fraction of M dwarfs, 30-40%, is lower than that of earlier type main sequence stars, and there are more companions to M dwarfs found between 1 and 10 AU than in any other decade interval. We find that the luminosity function of the lowest mass stars is flat or rising to the end of the main sequence, and that the mass function undoubtedly rises to the stellar/substellar break. We illustrate that the resolution of close binaries is crucial if accurate luminosity and mass functions are to be determined. Finally, we estimate 0.02 M(⊙)/pc³ to be the amount of mass contributed by M dwarfs to the galactic mass. Based upon new mass-luminosity relations developed at infrared wavelengths using a sample of stars with well-determined masses between 1.2 and 0.08 M(⊙), we are able to define empirically the end of the main sequence. We present absolute magnitudes, colors and spectral types for objects at the theoretical lowest stellar mass. Using these relations, we conclude that a few brown dwarfs may have already been discovered. (Abstract shortened with permission of author.)
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Cook, Neil James. "M dwarfs from the SDSS, 2MASS and WISE surveys : identification, characterisation and unresolved ultracool companionship." Thesis, University of Hertfordshire, 2016. http://hdl.handle.net/2299/17244.

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The aim of this thesis is to use a cross-match between WISE, 2MASS and SDSS to identify a large sample of M dwarfs. Through the careful characterisation and quality control of these M dwarfs I aim to identify rare systems (i.e. unresolved UCD companions, young M dwarfs, late M dwarfs and M dwarfs with common proper motion companions). Locating ultracool companions to M dwarfs is important for constraining low-mass formation models, the measurement of substellar dynamical masses and radii, and for testing ultracool evolutionary models. This is done by using an optimised method for identifying M dwarfs which may have unresolved ultracool companions. To do this I construct a catalogue of 440 694 M dwarf candidates, from WISE, 2MASS and SDSS, based on optical- and near-infrared colours and reduced proper motion. With strict reddening, photometric and quality constraints I isolate a sub-sample of 36 898 M dwarfs and search for possible mid-infrared M dwarf + ultracool dwarf candidates by comparing M dwarfs which have similar optical/near-infrared colours (chosen for their sensitivity to effective temperature and metallicity). I present 1 082 M dwarf + ultracool dwarf candidates for follow-up. Using simulated ultracool dwarf companions to M dwarfs, I estimate that the occurrence of unresolved ultracool companions amongst my M dwarf + ultracool dwarf candidates should be at least four times the average for my full M dwarf catalogue. I discuss yields of candidates based on my simulations. The possible contamination and bias from misidentified M dwarfs is then discussed, from chance alignments with other M dwarfs and UCDs, from chance alignments with giant stars, from chance alignments with galaxies, and from blended systems (via visual inspection). I then use optical spectra from LAMOST to spectral type a subset of my M dwarf + ultracool dwarf candidates. These candidates need confirming as true M dwarf + ultracool dwarf systems thus I present a new method I developed to use low resolution near-infrared spectra which relies on two colour similar objects (one an excess candidate, one not) having very similar spectra. A spectral difference of these two colour similar objects should leave the signature of a UCD in the residual of their differences, which I look for using the difference in two spectral bands designed to identify UCD spectral features. I then present the methods used to identify other rare systems from my full M dwarf catalogue. Young M dwarfs were identified by measuring equivalent widths of Hα from the LAMOST spectra, and by measuring rotation periods from Kepler 2 light curves. I identify late M dwarfs photometrically (using reduced proper motion and colour cuts) and spectroscopically (using the LAMOST spectra with spectral indices from the literature). Also I present common proper motion analysis aimed at finding Tycho-2 primaries for my M dwarfs and look for physically separated M dwarf + M dwarf pairs (internally within my full M dwarf catalogue).
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5

Clanton, Christian Dwain. "The Demographics of Exoplanetary Companions to M Dwarfs: Synthesizing Results from Microlensing, Radial Velocity, and Direct Imaging Surveys." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1459947520.

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6

Hynes, Robert Ian. "Observations of low mass X-ray transients in outburst." Thesis, n.p, 1999. http://library7.open.ac.uk/abstracts/page.php?thesisid=48.

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7

Bonnefoy, Mickaël. "Recherche et caractérisation des propriétés physiques et chimiques des compagnons de faible masse, naines brunes et planètes géantes, à l'aide d'observations à haut contraste et à haute résolution angulaire." Grenoble, 2010. http://www.theses.fr/2010GRENY035.

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Mon travail de thèse se place dans le contexte dynamique de la détection directe des compagnons de faible masse (naines brunes, planètes extrasolaires) dans le but de caractériser leurs propriétés physiques et chimiques et de comprendre leurs mécanismes de formation et d'évolution. Cette recherche requiert l'emploi de techniques d'observations à haut contraste et à haute résolution angulaire pour résoudre l'environnement proche des étoiles et ne pas être limité par leur flux. Dans ce cadre, j'ai eu la chance de participer à des campagnes d'observations pour tenter de détecter de nouvelles sources. J'ai élaboré un ensemble d'outils de traitement et d'analyse des données pour extraire les spectres et les flux des objets dans des bandes photométriques. Enfin, j'ai utilisé ces informations pour étudier les propriétés physiques (rayon, masse, âge) et atmosphériques (composition, température effective, gravité de surface) de ces objets. La première partie de ce manuscrit se focalise sur la détection par imagerie des compagnons de faible masse jeunes (< 100 millions d'années). Je décris un ensemble d'outils de réduction et d'analyse, spécifiques à la technique d'imagerie angulaire différentielle, que j'ai mis en place. Ces outils ont été utilisés sur des données provenant de l'instrument NaCo situé au Very Large Telescope (Chili). Ils ont permis de redétecter la planète extrasolaire β Pictoris b. Ce compagnon est le plus proche de son étoile de toutes les exoplanètes détectées directement. Cette découverte fournit la preuve directe que des planètes géantes se forment en moins de 12 millions d'années à l'intérieur de disques. Je présente enfin l'analyse complémentaire que j'ai menée pour initier la caractérisation de cet objet particulier. Le second volet de mon travail, présenté dans la deuxième partie du manuscrit, est axé sur la détermination des propriétés spectroscopiques dans le proche infrarouge (1. 1-2. 5 µm) des objets de faible masse jeunes. Ce travail a débuté par l'optimisation et le développement d'outils de traitement et d'analyse des données du spectrographe intégral de champ SINFONI assisté par optique adaptative. Les efforts déployés ont permis d'analyser le spectre du compagnon naine brune/exoplanète AB Pic b. Ce travail s'est poursuivi par la construction d'une bibliothèque de spectres d'objets jeunes. Cette bibliothèque fournie un ensemble de spectres de référence pour l'étude des compagnons détectés. Elle apporte des contraintes inédites sur les dernières générations de modèles d'atmosphère froids. Enfin, j'ai tiré parti de l'expérience acquise sur les instruments NaCo et SINFONI pour caractériser le système binaire TWA 22AB qui pourrait calibrer les modèles d'évolution des objets de faible masse
My work takes place in the dynamic context of the direct detection of low mass companions (brown dwarfs, extrasolar planets). I intent to characterize their physical and chemical properties, and to understand the mechanisms that lead to their formation and drive their evolution. This requires using high contrast and high angular resolution techniques in order to resolve the close environment of the stars without being limited by their flux. I had the opportunity to participate to observational campaigns so as to detect new sources. I developed a set of data analysis tools designed to extract the spectra and the flux of the objects into photometric bands. Finally, I used this information to study the physical (radius, mass, age) and the atmospheric (composition, effective temperature, surface gravity) properties of these objects. The first part of this manuscript focus on the detection of young (age < 100 Myrs) low mass companions using imaging. I describe a set of reduction and analysis tools dedicated to the angular differential imaging technique. These tools have been used on data coming from the NaCo instrument located on the Very Large Telescope (Chile). They allowed re-detecting the extrasolar planet β Pictoris b. This companion is closer to its star than any of the extrasolar planets detected directly so far. This discovery brings the definite proof that giant planets can form in less than 12 million years within disks. I finally present a complementary analysis I conducted to initiate the characterization of this valuable object. The determination of the spectroscopic properties of young and low mass objects in the near infrared (1. 1-2. 5 µm) constitutes the second aspect of my work (and is reported in the last part of the manuscript). I started developing analysis and processing tools dedicated to data gathered on the adaptive optics assisted integral field spectrograph SINFONI. These efforts were used to analyze the spectrum of the planet/brown dwarf companion AB Pic b. This work was pursued to built a spectral library of young objects. This library brings a collection of reference spectra, necessary for the study of other young companions. It also brings new constraints on the latest generation of atmospheric models of cool objects. To conclude, I used the instrument NaCo and SINFONI to characterize the binary system TWA 22AB that could calibrate evolutionary models of low mass objects
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Milli, J., P. Hibon, V. Christiaens, É. Choquet, M. Bonnefoy, G. M. Kennedy, M. C. Wyatt, et al. "Discovery of a low-mass companion inside the debris ring surrounding the F5V star HD 206893." EDP SCIENCES S A, 2016. http://hdl.handle.net/10150/622878.

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Aims. Uncovering the ingredients and the architecture of planetary systems is a very active field of research that has fuelled many new theories on giant planet formation, migration, composition, and interaction with the circumstellar environment. We aim at discovering and studying new such systems, to further expand our knowledge of how low-mass companions form and evolve. Methods. We obtained high-contrast H-band images of the circumstellar environment of the F5V star HD 206893, known to host a debris disc never detected in scattered light. These observations are part of the SPHERE High Angular Resolution Debris Disc Survey (SHARDDS) using the InfraRed Dual-band Imager and Spectrograph (IRDIS) installed on VLT/SPHERE. Results. We report the detection of a source with a contrast of 3 : 6 x 10(-5) in the H-band, orbiting at a projected separation of 270 milliarcsec or 10 au, corresponding to a mass in the range 24 to 73 M-Jup for an age of the system in the range 0.2 to 2 Gyr. The detection was confirmed ten months later with VLT /NaCo, ruling out a background object with no proper motion. A faint extended emission compatible with the disc scattered light signal is also observed. Conclusions. The detection of a low-mass companion inside a massive debris disc makes this system an analog of other young planetary systems such as beta Pictoris, HR 8799 or HD 95086 and requires now further characterisation of both components to understand their interactions.
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Johnson-Groh, Mara, Christian Marois, Rosa Robert J. De, Eric L. Nielsen, Julien Rameau, Sarah Blunt, Jeffrey Vargas, et al. "Integral Field Spectroscopy of the Low-mass Companion HD 984 B with the Gemini Planet Imager." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/623816.

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We present new observations of the low-mass companion to HD 984 taken with the Gemini Planet Imager (GPI) as a part of the GPI Exoplanet Survey campaign. Images of HD 984 B were obtained in the J (1.12-1.3 mu m) and H (1.50-1.80 mu m) bands. Combined with archival epochs from 2012 and 2014, we fit the first orbit to the companion to find an 18 au (70-year) orbit with a 68% confidence interval between 14 and 28 au, an eccentricity of 0.18 with a 68% confidence interval between 0.05 and 0.47, and an inclination of 119 degrees with a 68% confidence interval between 114 degrees and 125 degrees. To address the considerable spectral covariance in both spectra, we present a method of splitting the spectra into low and high frequencies to analyze the spectral structure at different spatial frequencies with the proper spectral noise correlation. Using the split spectra, we compare them to known spectral types using field brown dwarf and low-mass star spectra and find a best-fit match of a field gravity M6.5 +/- 1.5 spectral type with a corresponding temperature of 2730(-180)(+120)K. Photometry of the companion yields a luminosity of log(L-bol/L-circle dot) = -2.88 +/- 0.07 dex with DUSTY models. Mass estimates, again from DUSTY models, find an age-dependent mass of 34 +/- 1 to 95 +/- 4 M-Jup. These results are consistent with previous measurements of the object.
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10

Manjavacas, Elena, Dániel Apai, Yifan Zhou, Theodora Karalidi, Ben W. P. Lew, Glenn Schneider, Nicolas Cowan, et al. "Cloud Atlas: Discovery of Rotational Spectral Modulations in a Low-mass, L-type Brown Dwarf Companion to a Star." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/626404.

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Observations of rotational modulations of brown dwarfs and giant exoplanets allow the characterization of condensate cloud properties. As of now, rotational spectral modulations have only been seen in three L-type brown dwarfs. We report here the discovery of rotational spectral modulations in LP261-75B, an L6-type intermediate surface gravity companion to an M4.5 star. As a part of the Cloud Atlas Treasury program, we acquired time-resolved Wide Field Camera 3 grism spectroscopy (1.1-1.69 mu m) of LP261-75B. We find gray spectral variations with the relative amplitude displaying only a weak wavelength dependence and no evidence for lower-amplitude modulations in the 1.4. mu m water band than in the adjacent continuum. The likely rotational modulation period is 4.78 +/- 0.95. hr, although the rotational phase is not well sampled. The minimum relative amplitude in the white light curve measured over the whole wavelength range is 2.41% +/- 0.14%. We report an unusual light curve, which seems to have three peaks approximately evenly distributed in rotational phase. The spectral modulations suggests that the upper atmosphere cloud properties in LP261-75B are similar to two other mid-L dwarfs of typical infrared colors, but differ from that of the extremely red L-dwarf WISE0047.
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Книги з теми "Low mass companions"

1

Alasdair, Bleakley, and Eneberi Jeffrey, eds. Intellectual property and media law companion. 4th ed. Haywards Heath, West Sussex: Bloomsbury Professional, 2010.

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2

A, Golimowski David, and United States. National Aeronautics and Space Administration., eds. Hubble Space Telescope observations of the very low mass companion to Gliese 105A. [Washington, DC: National Aeronautics and Space Administration, 1995.

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3

Andenæs, Mads Henry, Gudmund Knudsen, Kristin Normann, and Geir Woxholth. Selskap, kontrakt, konkurs og rettskilder: Festskrift til Mads Henry Andenæs 70 år. Oslo: Gyldendal Akademisk, 2010.

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4

Hilken, Arnold. Tendenzbestimmung in Medienkonzernen. [Düsseldorf]: Hans-Böckler-Stiftung, 1986.

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5

Media Law Companion (Legal Practice Course Companion). Routledge Cavendish, 2005.

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6

Bloy, Duncan J. Media Law (SAGE Course Companions). Sage Publications Ltd, 2007.

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7

Bloy, Duncan J. Media Law (SAGE Course Companions). Sage Publications Ltd, 2007.

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8

Watson, Kerry, Marcus Anselm, and Alasdair Bleakley. Intellectual Property and Media Law Companion (Legal Practice Companion). 3rd ed. Blackstone Press, 1999.

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9

Watson, Kerry, Marcus Anselm, and Alasdair Bleakley. Intellectual Property and Media Law Companion (Legal Practice Course Companion). 4th ed. Cavendish Pub Ltd, 2005.

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10

Dabney, Farrell. Companion to Media and Humanitarian Action. Scitus Academics LLC, 2018.

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Частини книг з теми "Low mass companions"

1

Sazhin, M. V., and I. A. Trifalenkov. "An Indirect Search for Low-Mass Companions to Distant Stars." In High Angular Resolution in Astrophysics, 391–95. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-009-0041-7_26.

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2

Macintosh, B., B. Zuckerman, E. E. Becklin, and I. S. McLean. "A Near-Infrared Imaging Search for Low Mass Companions to Hyades Stars." In Infrared Astronomy with Arrays, 231–34. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-1070-9_74.

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3

Hubrig, Swetlana, Markus Schöller, David Le Mignant, Beate Stelzer, Nuria Huélamo, and Gaspard Duchêne. "First Spectroscopic Observations of Low-Mass Companions to X-Ray Selected Main Sequence Late B-type Dwarfs with NIRSPEC at Keck II." In High Resolution Infrared Spectroscopy in Astronomy, 499–502. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/10995082_79.

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4

Mazeh, Tsevi, David W. Latham, Robert P. Stefanik, Guillermo Torres, and Eti Wasserman. "A Radial-Velocity Search for Brown Dwarfs and the Low-Mass Companion of HD114762." In Active Close Binaries, 267–76. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0679-2_22.

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5

Monin, J. L., F. Ménard, N. Ageorges, and A. Eckart. "SHARP Images of the Pre-main Sequence Star V536 Aquilae: A Binary with a Low-Mass Companion." In The Bottom of the Main Sequence — And Beyond, 109–12. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-540-49217-7_17.

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6

Binawan, Akhwan, and Takamasa Osawa. "The Value of Participatory Mapping, the Role of the Adat Community (Masyarakat Adat), and the Future of the Peatlands." In Global Environmental Studies, 211–37. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-0902-5_10.

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AbstractIndonesian central and local governments have not made serious effort to recognize and protect the rights of the adat community (masyarakat adat; indigenous/traditional community) or adat law community (masytarakat hukum adat; customary law community), despite the Indonesian Constitution of 1945 and many national laws enacted to recognize such rights. In practice, government institutions facilitate conversation of traditional forest lands to other uses, often plantations. Rantau Baru is one adat community where customary territorial management has been eroded by outsider interests, including concession companies, leading to social conflict and environmental damages, including peatland fires. By presenting maps produced from the perspective of the Rantau Baru villagers, this chapter explores the difficulties that adat communities face regarding government mapping policies and suggests the significance of participatory mapping projects to re-establish sustainable adat community management of customary lands.
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7

Fenwick, Alan, Wendie Norris, and Becky McCall. "Accelerating control of NTDs and schistosomiasis in particular, 2008-2020." In A tale of a man, a worm and a snail: the schistosomiasis control initiative, 224–36. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781786392558.0019.

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Abstract Public health in sub-Saharan Africa, even after COVID-19, has reached a critical mass that promises positive change for nearly a billion poorest in the world. This change is driven by the expansion interested in "neglected tropical diseases" or NTDs, ironically called, and the success of the built-in control programs for them. Now the removal of the disease in 2030, most consumers are in the spotlight due to continued community support: private partnerships for drug funding from pharmaceutical companies, bilateral sponsors (UK and US), fundraising organisations (GiveWell, GWWC, The END Fund), implementing NGOs (RTI, SCI, GAELF) and ministries of education and health care in endemic countries. There's still a lot of work to do resulted in elimination, but the word "forgotten" in the context of the tropics illness may no longer be true. NTD has since been practically unknown in the 20th century outside the poor and rural areas of the world, to a situation where, at the beginning of the 21st century, more than a billion treatments were performed each year.
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8

Higano, Yoshiro. "Introduction: Real Estate Tax System and Real Estate Market in Japan." In New Frontiers in Regional Science: Asian Perspectives, 115–22. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-8848-8_8.

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AbstractThis introduction summarizes chapters of Part II. In Chap. 10.1007/978-981-15-8848-8_9, Yamamoto (Jpn J Real Estate Sci 31:88–96, 2018) has compared between the street method, the asset valuation adopted for the imposition of property tax in Japan, and the computer-assisted mass appraisal (CAMA) method generally adopted in North America focusing on education and training of valuators. In Chap. 10.1007/978-981-15-8848-8_10, Yamazaki (Jpn J Real Estate Sci 31:97–101, 2018) argues that one of the major causes for relatively low density use of land in the city in Japan is the land tax system. He focuses on property tax and examines defects of the tax from view of economist. In Chap. 10.1007/978-981-15-8848-8_11, Kobayashi (Jpn J Real Estate Sci 31:129–138, 2018), taking an actual example, has examined difference between precise legal interpretation of ‘exemption from real estate acquisition tax due to purpose of use’ and taxation practices conducted by local administrative bodies. In Chap. 10.1007/978-981-15-8848-8_12, Shirakawa and Okoshi (Jpn J Real Estate Sci 31:88–96, 2017) have shown that the real estate companies were committed to transactions as dual agencies to whatsoever degree, and analyzed attributes of real estate brokerage companies which are able to be dual agencies and how such dual agency affects contract price.In Chap. 10.1007/978-981-15-8848-8_13, Ueno (Jpn J Real Estate Sci 31:97–105, 2017) has analyzed impacts of the macroeconomic conditions on the land price gradient curves which are estimated using real estate data of the Tokyo Metropolitan Area in 1970, 1976, 1985, 1988, 1994, 2008, 2010, and 2016. In Chap. 10.1007/978-981-15-8848-8_14, Komatsu (Jpn J Real Estate Sci 31:110–118, 2017) has analyzed impacts that refurbishment of existing apartment has on possible increase in rent using the multinomial probit model and the Tobit model. In Chap. 10.1007/978-981-15-8848-8_15, Hanazato (Jpn J Real Estate Sci 31:119–128, 2017) has shown that around 90% of condominium reconstruction cases are predictable using the estimated discriminant function in terms of objective real estate data only. In Chap. 10.1007/978-981-15-8848-8_16, Ota et al. (Jpn J Real Estate Sci 31:109–119, 2018) have analyzed determinants of rent for rental house, office, and shop within 10-min walking distance from Shibuya Station in Tokyo. Multiple regression analyses are conducted and have shown that space syntax (SS) measures (Hillier and Hanson, The Social Logic of Space. Cambridge University Press, Cambridge, 1984) significantly affect rent as well as conventional location attributes.
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9

Preti, Sara, and Enrico di Bella. "Gender Equality as EU Strategy." In Social Indicators Research Series, 89–117. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-41486-2_4.

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AbstractGender equality is an increasingly topical issue, but it has deep historical roots. The principle of gender equality found its legitimacy, even if limited to salary, in the 1957 Treaty of Rome, establishing the European Economic Community (EEC). This treaty, in Article 119, sanctioned the principle of equal pay between male and female workers. The EEC continued to protect women’s rights in the 1970s through equal opportunity policies. These policies referred, first, to the principle of equal treatment between men and women regarding education, access to work, professional promotion, and working conditions (Directive 75/117/EEC); second, to the principle of equal pay for male and female workers (Directive 76/207/EEC); and finally, enshrined the principle of equal treatment between men and women in matters of social security (Directive 79/7/EEC). Since the 1980s, several positive action programmes have been developed to support the role of women in European society. Between 1982 and 2000, four multiyear action programmes were implemented for equal opportunities. The first action programme (1982–1985) called on the Member States, through recommendations and resolutions by the Commission, to disseminate greater knowledge of the types of careers available to women, encourage the presence of women in decision-making areas, and take measures to reconcile family and working life. The second action programme (1986–1990) proposed interventions related to the employment of women in activities related to new technologies and interventions in favour of the equal distribution of professional, family, and social responsibilities (Sarcina, 2010). The third action programme (1991–1995) provided an improvement in the condition of women in society by raising public awareness of gender equality, the image of women in mass media, and the participation of women in the decision-making process at all levels in all areas of society. The fourth action programme (1996–2000) strengthened the existing regulatory framework and focused on the principle of gender mainstreaming, a strategy that involves bringing the gender dimension into all community policies, which requires all actors in the political process to adopt a gender perspective. The strategy of gender mainstreaming has several benefits: it places women and men at the heart of policies, involves both sexes in the policymaking process, leads to better governance, makes gender equality issues visible in mainstream society, and, finally, considers the diversity among women and men. Among the relevant interventions of the 1990s, it is necessary to recall the Treaty of Maastricht (1992) which guaranteed the protection of women in the Agreement on Social Policy signed by all Member States (except for Great Britain), and the Treaty of Amsterdam (1997), which formally recognised gender mainstreaming. The Treaty of Amsterdam includes gender equality among the objectives of the European Union (Article 2) and equal opportunity policies among the activities of the European Commission (Article 3). Article 13 introduces the principle of non-discrimination based on gender, race, ethnicity, religion, or handicaps. Finally, Article 141 amends Article 119 of the EEC on equal treatment between men and women in the workplace. The Charter of Fundamental Rights of the Nice Union of 2000 reaffirms the prohibition of ‘any discrimination based on any ground such as sex’ (Art. 21.1). The Charter of Fundamental Rights of the European Union also recognises, in Article 23, the principle of equality between women and men in all areas, including employment, work, and pay. Another important intervention of the 2000s is the Lisbon strategy, also known as the Lisbon Agenda or Lisbon Process. It is a reform programme approved in Lisbon by the heads of state and governments of the member countries of the EU. The goal of the Lisbon strategy was to make the EU the most competitive and dynamic knowledge-based economy by 2010. To achieve this goal, the strategy defines fields in which action is needed, including equal opportunities for female work. Another treaty that must be mentioned is that of Lisbon in 2009, thanks to which previous treaties, specifically the Treaty of Maastricht and the Treaty of Rome, were amended and brought together in a single document: the Treaty on European Union (TEU) and the Treaty on the Functioning of the European Union (TFEU). Thanks to the Lisbon Treaty, the Charter of Fundamental Rights has assumed a legally binding character (Article 6, paragraph 1 of the TEU) both for European institutions and for Member States when implementing EU law. The Treaty of Lisbon affirms the principle of equality between men and women several times in the text and places it among the values and objectives of the union (Articles 2 and 3 of the TEU). Furthermore, the Treaty, in Art. 8 of the TFEU, states that the Union’s actions are aimed at eliminating inequalities, as well as promoting equality between men and women, while Article 10 of the TFEU provides that the Union aims to ‘combat discrimination based on sex, racial or ethnic origin, religion or belief, disability, age, or sexual orientation’. Concerning the principle of gender equality in the workplace, the Treaty, in Article 153 of the TFEU, asserts that the Union pursues the objective of equality between men and women regarding labour market opportunities and treatment at work. On the other hand, Article 157 of the TFEU confirms the principle of equal pay for male and female workers ‘for equal work or work of equal value’. On these issues, through ordinary procedures, the European Parliament and the Council may adopt appropriate measures aimed at defending the principle of equal opportunities and equal treatment for men and women. The Lisbon Treaty also includes provisions relating to the fight against trafficking in human beings, particularly women and children (Article 79 of the TFEU), the problem of domestic violence against women (Article 8 of the TFEU), and the right to paid maternity leave (Article 33). Among the important documents concerning gender equality is the Roadmap (2006–2010). In 2006, the European Commission proposed the Roadmap for equality between women and men, in addition to the priorities on the agenda, the objectives, and tools necessary to achieve full gender equality. The Roadmap defines six priority areas, each of which is associated with a set of objectives and actions that makes it easier to achieve them. The priorities include equal economic independence for women and men, reconciliation of private and professional life, equal representation in the decision-making process, eradication of all forms of gender-based violence, elimination of stereotypes related to gender, and promotion of gender equality in external and development policies. The Commission took charge of the commitments included in the Roadmap, which were indirectly implemented by the Member States through the principle of subsidiarity and the competencies provided for in the Treaties (Gottardi, 2013). The 2006–2010 strategy of the European Commission is based on a dual approach: on the one hand, the integration of the gender dimension in all community policies and actions (gender mainstreaming), and on the other, the implementation of specific measures in favour of women aimed at eliminating inequalities. In 2006, the European Council approved the European Pact for Gender Equality which originated from the Roadmap. The European Pact for Gender Equality identified three macro areas of intervention: measures to close gender gaps and combat gender stereotypes in the labour market, measures to promote a better work–life balance for both women and men, and measures to strengthen governance through the integration of the gender perspective into all policies. In 2006, Directive 2006/54/EC of the European Parliament and Council regulated equal opportunities and equal treatment between male and female workers. Specifically, the Directive aims to implement the principle of equal treatment related to access to employment, professional training, and promotion; working conditions, including pay; and occupational social security approaches. On 21 September 2010, the European Commission adopted a new strategy to ensure equality between women and men (2010–2015). This new strategy is based on the experience of Roadmap (2006–2010) and resumes the priority areas identified by the Women’s Charter: equal economic independence, equal pay, equality in decision-making, the eradication of all forms of violence against women, and the promotion of gender equality and women’s empowerment beyond the union. The 2010–2015 Strategic Plan aims to improve the position of women in the labour market, but also in society, both within the EU and beyond its borders. The new strategy affirms the principle that gender equality is essential to supporting the economic growth and sustainable development of each country. In 2010, the validity of the Lisbon Strategy ended, the objectives of which were only partially achieved due to the economic crisis. To overcome this crisis, the Commission proposed a new strategy called Europe 2020, in March 2010. The main aim of this strategy is to ensure that the EU’s economic recovery is accompanied by a series of reforms that will increase growth and job creation by 2020. Specifically, Europe’s 2020 strategy must support smart, sustainable, and inclusive growth. To this end, the EU has established five goals to be achieved by 2020 and has articulated the different types of growth (smart, sustainable, and inclusive) in seven flagship initiatives. Among the latter, the initiative ‘an agenda for new skills and jobs’, in the context of inclusive growth, is the one most closely linked to gender policies and equal opportunities; in fact, it substantially aims to increase employment rates for women, young, and elderly people. The strategic plan for 2010–2015 was followed by a strategic commitment in favour of gender equality 2016–2019, which again emphasises the five priority areas defined by the previous plan. Strategic commitment, which contributes to the European Pact for Gender Equality (2011–2020), identifies the key actions necessary to achieve objectives for each priority area. In March 2020, the Commission presented a new strategic plan for equality between women and men for 2020–2025. This strategy defines a series of political objectives and key actions aimed at achieving a ‘union of equality’ by 2025. The main objectives are to put an end to gender-based violence and combat sexist stereotypes, ensure equal opportunities in the labour market and equal participation in all sectors of the economy and political life, solve the problem of the pay and pension gap, and achieve gender equality in decision-making and politics. From the summary of the regulatory framework presented, for the European Economic Community first, then for the European Community, and finally for the European Union, gender equality has always been a fundamental value. Interest in the issues of the condition of women and equal opportunities has grown over time and during the process of European integration, moving from a perspective aimed at improving the working conditions of women to a new dimension to improve the life of the woman as a person, trying to protect her not only professionally but also socially, and in general in all those areas in which gender inequality may occur. The approach is extensive and based on legislation, the integration of the gender dimension into all policies, and specific measures in favour of women. From the non-exhaustive list of the various legislative interventions, it is possible to note a continuous repetition of the same thematic priorities which highlights, on the one hand, the poor results achieved by the implementation of the policies, but, on the other hand, the Commission’s willingness to pursue the path initially taken. Among the achievements in the field of gender equality obtained by the EU, there is certainly an increase in the number of women in the labour market and the acquisition of better education and training. Despite progress, gender inequalities have persisted. Even though women surpass men in terms of educational attainment, gender gaps still exist in employment, entrepreneurship, and public life (OECD, 2017). For example, in the labour market, women continue to be overrepresented in the lowest-paid sectors and underrepresented in top positions (according to the data released in the main companies of the European Union, women represent only 8% of CEOs).
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Ladders, Katharina, and Bruce Fegley. "Jupiter, Rings, and Satellites." In The Planetary Scientist’s Companion, 199–208. Oxford University PressNew York, NY, 1998. http://dx.doi.org/10.1093/oso/9780195116946.003.0008.

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Abstract Jupiter’s low density and large mass, as well as its atmospheric composition, indicate that it is dominantly H2 and He, with composition close to the sun’s; interior structure models reinforce this conclusion. The ob-served D/H ratio, which would have been increased by accretion of large amounts of ices (e.g., H20, CH4, NH3) during Jupiter’s formation, also indicates that Jupiter’s composition is close to that of the sun and is only slightly enriched in elements heavier than He.
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Тези доповідей конференцій з теми "Low mass companions"

1

Classen, L., S. Geier, U. Heber, S. J. O’Toole, Klaus Werner, and T. Rauch. "RV survey of low-mass companions to sdB stars." In 17TH EUROPEAN WHITE DWARF WORKSHOP. AIP, 2010. http://dx.doi.org/10.1063/1.3527814.

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den Hartog, Roland H., Olivier Absil, Philippe A. Gondoin, Luigi L. A. d'Arcio, Pierre Fabry, Lisa Kaltenegger, Rainer C. Wilhelm, Philippe B. Gitton, Florence Puech, and C. V. M. Fridlund. "The simulated detection of low-mass companions with GENIE." In SPIE Astronomical Telescopes + Instrumentation, edited by Wesley A. Traub. SPIE, 2004. http://dx.doi.org/10.1117/12.552563.

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3

Classen, Lew, Stephan Geier, Ulrich Heber, and Simon J. O’Toole. "Radial Velocity Survey of Low-Mass Companions to sdB Stars." In PLANETARY SYSTEMS BEYOND THE MAIN SEQUENCE: Proceedings of the International Conference. AIP, 2011. http://dx.doi.org/10.1063/1.3556215.

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4

Allen, Peter R., and Eric Stempels. "Low-Mass Tertiary Companions to Spectroscopic Binaries: Common Proper Motion Survey for Wide Companions using 2MASS." In COOL STARS, STELLAR SYSTEMS AND THE SUN: Proceedings of the 15th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun. AIP, 2009. http://dx.doi.org/10.1063/1.3099243.

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5

Zurlo, A., D. Mesa, R. Gratton, R. Claudi, S. Desidera, E. Giro, J. L. Beuzit, et al. "Methods for the detection and the characterization of low mass companions using the IFS of SPHERE." In SPIE Astronomical Telescopes + Instrumentation, edited by Suzanne K. Ramsay, Ian S. McLean, and Hideki Takami. SPIE, 2014. http://dx.doi.org/10.1117/12.2055085.

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6

Siegler, Nicholas, Laird M. Close, and Melanie E. Freed. "Guiding on the edge (V~19): results from an AO survey of very low mass stars searching for extremely faint companions." In Astronomical Telescopes and Instrumentation, edited by Peter L. Wizinowich and Domenico Bonaccini. SPIE, 2003. http://dx.doi.org/10.1117/12.460085.

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7

Salama, Maïssa, Christoph Baranec, Rebecca Jensen-Clem, Reed Riddle, Dmitry Duev, Shrinivas Kulkarni, and Nicholas M. Law. "Robo-AO Kitt Peak: status of the system and deployment of a sub-electron readnoise IR camera to detect low-mass companions." In SPIE Astronomical Telescopes + Instrumentation, edited by Enrico Marchetti, Laird M. Close, and Jean-Pierre Véran. SPIE, 2016. http://dx.doi.org/10.1117/12.2233741.

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8

Schaffenroth, V., S. Geier, U. Heber, H. Drechsel, R. H. O̸stensen, P. F. L. Maxted, T. Kupfer, B. N. Barlow, Klaus Werner, and T. Rauch. "Analysis of two eclipsing hot subdwarf binaries with a low mass stellar and a brown dwarf companion." In 17TH EUROPEAN WHITE DWARF WORKSHOP. AIP, 2010. http://dx.doi.org/10.1063/1.3527813.

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9

Schaffenroth, Veronika, Stephan Geier, Ulrich Heber, Horst Drechsel, Roy H. O̸stensen, Pierre F. L. Maxted, Thomas Kupfer, and Brad N. Barlow. "Analysis of Two Eclipsing Hot Subdwarf Binaries with a Low Mass Stellar and a Brown Dwarf Companion." In PLANETARY SYSTEMS BEYOND THE MAIN SEQUENCE: Proceedings of the International Conference. AIP, 2011. http://dx.doi.org/10.1063/1.3556199.

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Schaffenroth, V., S. Geier, U. Heber, H. Drechsel, R. H. O̸stensen, P. F. L. Maxted, T. Kupfer, B. N. Barlow, Vicky Kologera, and Marc van der Sluys. "Analysis of Two Eclipsing Hot Subdwarf Binaries with a Low Mass Stellar and a Brown Dwarf Companion." In INTERNATIONAL CONFERENCE ON BINARIES: In celebration of Ron Webbink’s 65th Birthday. AIP, 2010. http://dx.doi.org/10.1063/1.3536422.

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Звіти організацій з теми "Low mass companions"

1

Scholl, Lynn, German Lleras, Daniel Oviedo, Jose Castro, and Orlando Sabogal-Cardona. The Potential for Ride-hailing Integration with Mass Transit Systems: A choice Experiment in Latin America. Inter-American Development Bank, February 2024. http://dx.doi.org/10.18235/0005549.

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As transportation alternatives facilitated by TNCs (Transportation Network Companies) have gained popularity around the world, research has increasingly focused on understanding their impacts on urban mobility, with several studies examining whether they are competing with public transit trips, increasing vehicle kilometers, or contributing to congestion. Recent policy discussions have turned to whether these services could also have positive benefits, such as complementing mass transit services as a first- and last-mile solution. Most research to date has focused on industrialized countries, with little work focusing on Global South cities. Seeking to fill significant evidence gaps on the impacts of ride-hailing on travel behavior, this paper builds on a stated preference survey in three large metropolitan areas in Latin America (Bogota, Medellin, and Mexico City) to evaluate the potential of introducing an integrated scheme of ride-hailing and mass transit. The scenario of the integrated scheme places ride-hailing as a filler of the first- and last-mile gap left by mass transit. We use discrete choice models and simulations to assess the potential for modal shifts under different pricing scenarios. Results suggest limited feasibility (or modal shifts) of an integrated system of ride-hailing with mass transit under the scenarios considered. Even with significant discounts on the integrated fare, for two of the three cases, the additional ridership would remain comparatively low. Nevertheless, this opens the door for considering other app-based mobility options operating under a sharing perspective and that can reduce operative costs in an integrated scheme.
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2

Anderson, Gerald L., and Kalman Peleg. Precision Cropping by Remotely Sensed Prorotype Plots and Calibration in the Complex Domain. United States Department of Agriculture, December 2002. http://dx.doi.org/10.32747/2002.7585193.bard.

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This research report describes a methodology whereby multi-spectral and hyperspectral imagery from remote sensing, is used for deriving predicted field maps of selected plant growth attributes which are required for precision cropping. A major task in precision cropping is to establish areas of the field that differ from the rest of the field and share a common characteristic. Yield distribution f maps can be prepared by yield monitors, which are available for some harvester types. Other field attributes of interest in precision cropping, e.g. soil properties, leaf Nitrate, biomass etc. are obtained by manual sampling of the filed in a grid pattern. Maps of various field attributes are then prepared from these samples by the "Inverse Distance" interpolation method or by Kriging. An improved interpolation method was developed which is based on minimizing the overall curvature of the resulting map. Such maps are the ground truth reference, used for training the algorithm that generates the predicted field maps from remote sensing imagery. Both the reference and the predicted maps are stratified into "Prototype Plots", e.g. 15xl5 blocks of 2m pixels whereby the block size is 30x30m. This averaging reduces the datasets to manageable size and significantly improves the typically poor repeatability of remote sensing imaging systems. In the first two years of the project we used the Normalized Difference Vegetation Index (NDVI), for generating predicted yield maps of sugar beets and com. The NDVI was computed from image cubes of three spectral bands, generated by an optically filtered three camera video imaging system. A two dimensional FFT based regression model Y=f(X), was used wherein Y was the reference map and X=NDVI was the predictor. The FFT regression method applies the "Wavelet Based", "Pixel Block" and "Image Rotation" transforms to the reference and remote images, prior to the Fast - Fourier Transform (FFT) Regression method with the "Phase Lock" option. A complex domain based map Yfft is derived by least squares minimization between the amplitude matrices of X and Y, via the 2D FFT. For one time predictions, the phase matrix of Y is combined with the amplitude matrix ofYfft, whereby an improved predicted map Yplock is formed. Usually, the residuals of Y plock versus Y are about half of the values of Yfft versus Y. For long term predictions, the phase matrix of a "field mask" is combined with the amplitude matrices of the reference image Y and the predicted image Yfft. The field mask is a binary image of a pre-selected region of interest in X and Y. The resultant maps Ypref and Ypred aremodified versions of Y and Yfft respectively. The residuals of Ypred versus Ypref are even lower than the residuals of Yplock versus Y. The maps, Ypref and Ypred represent a close consensus of two independent imaging methods which "view" the same target. In the last two years of the project our remote sensing capability was expanded by addition of a CASI II airborne hyperspectral imaging system and an ASD hyperspectral radiometer. Unfortunately, the cross-noice and poor repeatability problem we had in multi-spectral imaging was exasperated in hyperspectral imaging. We have been able to overcome this problem by over-flying each field twice in rapid succession and developing the Repeatability Index (RI). The RI quantifies the repeatability of each spectral band in the hyperspectral image cube. Thereby, it is possible to select the bands of higher repeatability for inclusion in the prediction model while bands of low repeatability are excluded. Further segregation of high and low repeatability bands takes place in the prediction model algorithm, which is based on a combination of a "Genetic Algorithm" and Partial Least Squares", (PLS-GA). In summary, modus operandi was developed, for deriving important plant growth attribute maps (yield, leaf nitrate, biomass and sugar percent in beets), from remote sensing imagery, with sufficient accuracy for precision cropping applications. This achievement is remarkable, given the inherently high cross-noice between the reference and remote imagery as well as the highly non-repeatable nature of remote sensing systems. The above methodologies may be readily adopted by commercial companies, which specialize in proving remotely sensed data to farmers.
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Stewart, Jonathan, Grace Parker, Joseph Harmon, Gail Atkinson, David Boore, Robert Darragh, Walter Silva, and Youssef Hashash. Expert Panel Recommendations for Ergodic Site Amplification in Central and Eastern North America. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, March 2017. http://dx.doi.org/10.55461/tzsy8988.

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The U.S. Geological Survey (USGS) national seismic hazard maps have historically been produced for a reference site condition of VS30 = 760 m/sec (where VS30 is time averaged shear wave velocity in the upper 30 m of the site). The resulting ground motions are modified for five site classes (A-E) using site amplification factors for peak acceleration and ranges of short- and long-oscillator periods. As a result of Project 17 recommendations, this practice is being revised: (1) maps will be produced for a range of site conditions (as represented by VS30 ) instead of a single reference condition; and (2) the use of site factors for period ranges is being replaced with period-specific factors over the period range of interest (approximately 0.1 to 10 sec). Since the development of the current framework for site amplification factors in 1992, the technical basis for the site factors used in conjunction with the USGS hazard maps has remained essentially unchanged, with only one modification (in 2014). The approach has been to constrain site amplification for low-to-moderate levels of ground shaking using inference from observed ground motions (approximately linear site response), and to use ground response simulations (recently combined with observations) to constrain nonlinear site response. Both the linear and nonlinear site response has been based on data and geologic conditions in the western U.S. (an active tectonic region). This project and a large amount of previous and contemporaneous related research (e.g., NGA-East Geotechnical Working Group for site response) has sought to provide an improved basis for the evaluation of ergodic site amplification in central and eastern North America (CENA). The term ‘ergodic’ in this context refers to regionally-appropriate, but not site-specific, site amplification models (i.e., models are appropriate for CENA generally, but would be expected to have bias for any particular site). The specific scope of this project was to review and synthesize relevant research results so as to provide recommendations to the USGS for the modeling of ergodic site amplification in CENA for application in the next version of USGS maps. The panel assembled for this project recommends a model provided as three terms that are additive in natural logarithmic units. Two describe linear site amplification. One of these describes VS30-scaling relative to a 760 m/sec reference, is largely empirical, and has several distinct attributes relative to models for active tectonic regions. The second linear term adjusts iv site amplification from the 760 m/sec reference to the CENA reference condition (used with NGA-East ground motion models) of VS =3000 m/sec; this second term is simulation-based. The panel is also recommending a nonlinear model, which is described in a companion report [Hashash et al. 2017a]. All median model components are accompanied by models for epistemic uncertainty. The models provided in this report are recommended for application by the USGS and other entities. The models are considered applicable for VS30 = 200–2000 m/sec site conditions and oscillator periods of 0.08–5 sec. Finally, it should be understood that as ergodic models, they lack attributes that may be important for specific sites, such as resonances at site periods. Site-specific analyses are recommended to capture such effects for significant projects and for any site condition with VS30 < 200 m/sec. We recommend that future site response models for hazard applications consider a two-parameter formulation that includes a measure of site period in addition to site stiffness.
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