Journal articles on the topic 'Exoplanets'
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Montemor, Ryan Nepomuceno, and Ricardo Roberto Plaza Teixceira. "Atividades de divulgação científica sobre exoplanetas." Revista Brasileira de Educação em Ciências e Educação Matemática 5, no. 2 (August 31, 2021): 445–60. http://dx.doi.org/10.33238/rebecem.2021.v.5.n.2.26865.
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Resumo: Este trabalho investigou os resultados e impactos de atividades de divulgação científica sobre a ciência dos exoplanetas, ocorridas em 2018, junto a alunos de quatro escolas de educação básica situadas em municípios do litoral norte paulista. Essas ações permitiram que os alunos adquirissem melhor compreensão acerca dos conceitos apresentados sobre exoplanetas e procuraram incentivar o aprofundamento no estudo de áreas da astronomia. Para a elaboração das apresentações estudou-se tanto o estado atual dos conhecimentos científicos sobre exoplanetas, quanto o modo como o trabalho didático com temas de astronomia pode ser efetuado a alunos dos ensinos fundamental e médio. Nas apresentações foram usados diferentes recursos que procuraram tornar mais compreensíveis os conceitos científicos envolvidos e as técnicas de detecção de exoplanetas. Em particular, considerou-se o caráter interdisciplinar da ciência dos exoplanetas, bem como, conhecimentos relacionados à história da astronomia.Palavras-chave: Astronomia; Ensino de Física; Divulgação da Ciência; Detecção de Exoplanetas. Scientific dissemination activities on exoplanetsAbstract: This work investigated the results and impacts of scientific dissemination activities on the science of exoplanets, which took place in 2018, with students from four schools of basic education located in municipalities on the north coast of São Paulo. These actions allowed students to gain a better understanding of the concepts presented about exoplanets and sought to encourage further study in areas of astronomy. For the elaboration of the presentations, it was studied both the current state of the existing scientific knowledge about exoplanets, as well as the way the didactic work with astronomy themes can be carried out with elementary and high school students. In the presentations, different resources were used to make the scientific concepts involved and the techniques for detecting exoplanets more understandable. In particular, the presentations considered the interdisciplinary nature of the science of exoplanets, as well as knowledge related to the history of astronomy.Keywords: Astronomy; Physics Teaching; Dissemination of Science; Exoplanet Detection.
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Varela, J., V. Réville, A. S. Brun, P. Zarka, and F. Pantellini. "Effect of the exoplanet magnetic field topology on its magnetospheric radio emission." Astronomy & Astrophysics 616 (August 2018): A182. http://dx.doi.org/10.1051/0004-6361/201732091.
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Context. The magnetized wind from stars that impact exoplanets should lead to radio emissions. According to the scaling laws derived in the solar system, the radio emission should depend on the stellar wind, interplanetary magnetic field, and topology of the exoplanet magnetosphere. Aims. The aim of this study is to calculate the dissipated power and subsequent radio emission from exoplanet magnetospheres with different topologies perturbed by the interplanetary magnetic field and stellar wind, to refine the predictions from scaling laws, and to prepare the interpretation of future radio detections. Methods. We use the magnetohydrodynamic (MHD) code PLUTO in spherical coordinates to analyze the total radio emission level resulting from the dissipation of the kinetic and magnetic (Poynting flux) energies inside the exoplanet’s magnetospheres. We apply a formalism to infer the detailed contribution in the exoplanet radio emission on the exoplanet’s day side and magnetotail. The model is based on Mercury-like conditions, although the study results are extrapolated to exoplanets with stronger magnetic fields, providing the lower bound of the radio emission. Results. The predicted dissipated powers and resulting radio emissions depend critically on the exoplanet magnetosphere topology and interplanetary magnetic field (IMF) orientation. The radio emission on the exoplanet’s night and day sides should thus contain information on the exoplanet magnetic field topology. In addition, if the topology of an exoplanet magnetosphere is known, the radio emission measurements can be used as a proxy of the instantaneous dynamic pressure of the stellar wind, IMF orientation, and intensity.
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Li, Megan G., Sofia Z. Sheikh, Christian Gilbertson, Matthias Y. He, Howard Isaacson, Steve Croft, and Evan L. Sneed. "Developing a Drift Rate Distribution for Technosignature Searches of Exoplanets." Astronomical Journal 166, no. 5 (October 17, 2023): 182. http://dx.doi.org/10.3847/1538-3881/acf83d.
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Abstract A stable-frequency transmitter with relative radial acceleration to a receiver will show a change in received frequency over time, known as a “drift rate.” For a transmission from an exoplanet, we must account for multiple components of drift rate: the exoplanet’s orbit and rotation, the Earth’s orbit and rotation, and other contributions. Understanding the drift rate distribution produced by exoplanets relative to Earth, can (a) help us constrain the range of drift rates to check in a Search for Extraterrestrial Intelligence project to detect radio technosignatures, and (b) help us decide validity of signals-of-interest, as we can compare drifting signals with expected drift rates from the target star. In this paper, we modeled the drift rate distribution for ∼5300 confirmed exoplanets, using parameters from the NASA Exoplanet Archive (NEA). We find that confirmed exoplanets have drift rates such that 99% of them fall within the ±53 nHz range. This implies a distribution-informed maximum drift rate ∼4 times lower than previous work. To mitigate the observational biases inherent in the NEA, we also simulated an exoplanet population built to reduce these biases. The results suggest that, for a Kepler-like target star without known exoplanets, ±0.44 nHz would be sufficient to account for 99% of signals. This reduction in recommended maximum drift rate is partially due to inclination effects and bias toward short orbital periods in the NEA. These narrowed drift rate maxima will increase the efficiency of searches and save significant computational effort in future radio technosignature searches.
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Wang, Zhixin. "Extrasolar Planet Candidates Identified by Single Transit from TESS." Journal of Physics: Conference Series 2441, no. 1 (March 1, 2023): 012030. http://dx.doi.org/10.1088/1742-6596/2441/1/012030.
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Abstract The discovery of planets around stars other than Sun was a grand milestone to understand origin and evolution of life in Universe. 2019 Nobel Prize for Physics was awarded to the first discovery of exoplanet around Sun-like stars, Peg 51b, in 1995. With development of 25 years, the current number of confirmed exoplanets have reached 4,000. The population of exoplanets presents great diversity and complexity beyond the planets in Solar system, severely challenging our understanding on the origin and evolution of planets. Moreover, clues of extrasolar life have been partially disclosed by detection of exoplanets in habitable zone with temporal surface temperature. In recent years, several promising surveys of exoplanets have been carried out to search for more exoplanets, compiling more complete sample of exoplanets and detecting Earth-like exoplanets. Transiting Exoplanet Survey Satellite (TESS) launched in 2018, is the most import facility for this purpose. It monitors the brightness of nearby stars in all sky with high cadences, searching for exoplanetary transit events. The survey is sensitive to detect terrestrial exoplanets. In this work, we reanalyzed the high quality light curves of TESS with algorithm developed by ourselves and visual examination. Our work was designed complementary to the automatic pipeline developed by TESS science team. TESS pipeline is not optimal for long-period exoplanets, for which only one transit event occurring in the observation sectors of 27.4 days, appearing as single transit single. Those long-period planets are more likely to be habitable with liquid water on their surface in relative large orbits. We took efforts to recover exoplanets with single transit in TESS. First, we identified candidates with significant narrow dimming in light curves uniformly by our automatic program. The singles were further examined visually and fitted by transit profile, selecting transit events. More precise modeling was carried out by MCMC analysis for transit exoplanet candidates. As a preliminary attempt, we only processed the light curves in sector 1 only. Full TESS dataset in all 26 sectors will be studied in future. In summary, we detected 25 exoplanet candidates in publicly accessible light curves in TESS sector 1. Among them, 14 candidates are known exoplanets, and 6 are candidates identified by TESS pipeline in catalog of Tess Objects of Interest (TOI). 5 exoplanet candidates with single transit signal are newly identified by their profiles, and the properties of these system were inferred in this work. The orbital parameters and physical properties derived by us are consistent with those in literature for all the 14 known exoplanets. 2 among 6 of exoplanet candidates in TOI catalog are single transit objects, our results are consistent with values reported in TOI catalog. For the new exoplanet candidates, we report their inferred orbits and physical sizes. We plan to implement our analysis for all light curves in 26 sectors of TESS, Over 100 exoplanet candidates are expected to be recovered, significantly contributing to the current population of 4,000 known exoplanets.
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Ulmer-Moll, S., N. C. Santos, P. Figueira, J. Brinchmann, and J. P. Faria. "Beyond the exoplanet mass-radius relation." Astronomy & Astrophysics 630 (October 2019): A135. http://dx.doi.org/10.1051/0004-6361/201936049.
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Context. Mass and radius are two fundamental properties for characterising exoplanets, but only for a relatively small fraction of exoplanets are they both available. Mass is often derived from radial velocity measurements, while the radius is almost always measured using the transit method. For a large number of exoplanets, either the radius or the mass is unknown, while the host star has been characterised. Several mass-radius relations that are dependent on the planet’s type have been published that often allow us to predict the radius. The same is true for a bayesian code, which forecasts the radius of an exoplanet given the mass or vice versa. Aims. Our goal is to derive the radius of exoplanets using only observables extracted from spectra used primarily to determine radial velocities and spectral parameters. Our objective is to obtain a mass-radius relation independent of the planet’s type. Methods. We worked with a database of confirmed exoplanets with known radii and masses, as well as the planets from our Solar System. Using random forests, a machine learning algorithm, we computed the radius of exoplanets and compared the results to the published radii. In addition, we explored how the radius estimates compare to previously published mass-radius relations. Results. The estimated radii reproduces the spread in radius found for high mass planets better than previous mass-radius relations. The average radius error is 1.8 R⊕ across the whole range of radii from 1–22 R⊕. We find that a random forest algorithm is able to derive reliable radii, especially for planets between 4 R⊕ and 20 R⊕ for which the error is under 25%. The algorithm has a low bias yet a high variance, which could be reduced by limiting the growth of the forest, or adding more data. Conclusions. The random forest algorithm is a promising method for deriving exoplanet properties. We show that the exoplanet’s mass and equilibrium temperature are the relevant properties that constrain the radius, and do so with higher accuracy than the previous methods.
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Yang, Gilbert. "Detection of Exoplanets based on the Transit Method." Highlights in Science, Engineering and Technology 31 (February 10, 2023): 196–203. http://dx.doi.org/10.54097/hset.v31i.5140.
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Exoplanets are planets orbiting a star other than the Sun. These exoplanets may exist in many different forms, such as a hot Jupiter and super earth. Detecting is the first step to further studying the properties of these exoplanets. In this paper, based on data of star Qatar-1 gathered from July 22nd 2022, a light flux curve is developed during the period of 04:28 - 07:01 UTC through which the star is observed. The presence of an exoplanet, presumably Qatar-1b, is revealed in the analyzing results of the collected data, showing the validity of the transit approach for exoplanet detection. By using this approach, exoplanets planets can be discovered for further research in regards to potentially habitable and/or resource-rich exoplanets.
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Gupta, Richa, and Sidratul Muntaha. "Identifying Potentially Habitable Exoplanets: A Study using the Transit Method and Kepler dataset." Applied and Computational Engineering 8, no. 1 (August 1, 2023): 93–97. http://dx.doi.org/10.54254/2755-2721/8/20230089.
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An exoplanet is a planet that orbits a star outside of our solar system. The study of exoplanets is an active area of research in astronomy. In this research, we aim to utilize the Kepler dataset provided by NASA EXOPLANET ACRCHIEVE to identify and classify exoplanets that could potentially support life. The Kepler dataset, which comprises of observations of over 150,000 stars, has been instrumental in the discovery of thousands of exoplanets. We will analyse the dataset using machine learning techniques to classify exoplanets as potentially habitable based on their orbital period, size, distance from their host star, and other parameters. The findings of this research will greatly enhance our understanding of the frequency of life in the universe and the use of machine learning techniques on the Kepler dataset will be an essential tool in the quest for finding potentially habitable exoplanets. Emerging Machine Learning Algorithms aid in detecting habitability of exoplanet in different stellar system. For finding an Exoplanet we have used the transit method which is based on the principle that when an exoplanet passes in front of its host star, it causes a temporary dip in the star's brightness. By monitoring the brightness of a star over time, scientists can detect these periodic dips and use them to infer the presence of an exoplanet. The findings of this research have the potential to significantly advance our understanding of the prevalence of life in the universe.
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Ashtari, Reza, Anthony Sciola, Jake D. Turner, and Kevin Stevenson. "Detecting Magnetospheric Radio Emission from Giant Exoplanets." Astrophysical Journal 939, no. 1 (October 28, 2022): 24. http://dx.doi.org/10.3847/1538-4357/ac92f5.
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Abstract As radio astronomy enters a golden age, ground-based observatories are reaching sensitivities capable of unlocking a new and exciting field of exoplanet observation. Radio observation of planetary auroral emission provides unique and complementary insight into planetary science not available via orthodox exoplanet observation techniques. Supplying the first measurements of planetary magnetic fields, rotation rates, and orbital obliquities, we gain necessary and crucial insight into our understanding of the star–planet relationships, geophysics, composition, and habitability of exoplanets. Using a stellar-wind-driven Jovian approximation, we present analytical methods for estimating magnetospheric radio emission from confirmed exoplanets. Predicted radio fluxes from cataloged exoplanets are compared against the wavelengths and sensitivities of current and future observatories. Candidate exoplanets are downselected based on the sky coverage of each ground-based observatory. Orbits of target exoplanets are modeled to account for influential orbit-dependent effects in anticipating time-varying exoplanet radio luminosity and flux. To evaluate the angular alignment of exoplanetary beamed emission relative to Earth’s position, the equatorial latitude of exoplanetary auroral emission is compared against Earth’s apparent latitude on the exoplanet. Predicted time-dependent measurements and recommended beamformed observations for ground-based radio arrays are provided, along with a detailed analysis of the anticipated emission behavior for τ Boo b.
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Sokoloff, Dmitry, Helmi Malova, and Egor Yushkov. "Symmetries of Magnetic Fields Driven by Spherical Dynamos of Exoplanets and Their Host Stars." Symmetry 12, no. 12 (December 15, 2020): 2085. http://dx.doi.org/10.3390/sym12122085.
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Observations of exoplanets open a new area of scientific activity and the structure of exoplanet magnetospheres is an important part of this area. Here we use symmetry arguments and experiences in spherical dynamo modeling to obtain the set of possible magnetic configurations for exoplanets and their corresponding host stars. The main part of our results is that the possible choice is much richer than the basic dipole magnetic field of both exoplanets and stars. Other options, for example, are quadrupole configurations or mixed parity solutions. Expected configurations of current sheets for the above mentioned exoplanet host star systems are presented as well.
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Ligi, Roxanne, Denis Mourard, Karine Perraut, Philippe Bério, Lionel Bigot, Andrea Chiavassa, Anne-Marie Lagrange, and Nicolas Nardetto. "Modeling transiting exoplanet and spots For interferometric study." Proceedings of the International Astronomical Union 9, S302 (August 2013): 202–5. http://dx.doi.org/10.1017/s1743921314002087.
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AbstractUp to now, many techniques have been developed to detect and observe exoplanets, the radial velocity (RV) method being the most prolific one. However, stellar magnetic spots can mimic an exoplanet transit signal and lead to a false detection. A few models have already been developed to constrain the different signature of exoplanets and spots, but they only concern RV measurements or photometry. An interferometric approach, with high angular resolution capabilities, could resolve this problem.Optical interferometry is a powerful method to measure accurate stellar diameters, and derive fundamental parameters of stars and exoplanets minimum masses. We have built an analytical code able to calculate visibility moduli and closure phases of stars with a transiting exoplanet, to be compared with a star with no exoplanet. From the difference of interferometric signal, we can derive the presence of the exoplanet, but this requires that the star is resolved enough. We have tested this code with current available facilities like VEGA/CHARA and determined which already discovered exoplanets systems can be resolved enough to test this method.To make a more general study, we also tested different parameters (exoplanet and stellar diameters, exoplanet position) that can lead to a variation of the minimum baseline length required to see the exoplanet signal on the visibility modulus and the phase. Stellar spots act in the same way, but the difference of local intensity between an exoplanet transit and a spot can easily be studied thanks to the interferometric measurements.
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Huang, Xinyue, Yuhan Yan, Shuangyu Yang, and Meng Yuan. "Discovering exoplanets in Pleiades with transiting exoplanet survey satellite." Theoretical and Natural Science 5, no. 1 (May 25, 2023): 532–39. http://dx.doi.org/10.54254/2753-8818/5/20230323.
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No transiting exoplanets have previously been found in the Pleiades. The Pleiades is a relatively young star cluster near us, which makes it valuable for investigation. This study aims to determine the existence of exoplanets in Pleiades using the transit method. Specifically, it sought to determine if the listed 83 stars have exoplanets by inspecting on light-curves from data of Transiting Exoplanet Survey Satellite (TESS). The TESS mission, with a better resolution and observed sky area than the previous Kepler mission, aimed to find more exoplanets around stars. To test the hypothesis that exoplanets do exist in the 83 stars of the Pleiades, we downloaded their light-curves using Jupyter notebook and the Lightkurve package, then checked using BLS method and fitting if there were transits. The results showed no clear sign of transiting planets in those stars. These results suggest that the 83 stars checked likely dont have a transiting exoplanet, but 83 stars cannot represent the whole Pleiades star cluster. Other methods should be used in analysis to gain more accurate results and more stars should be checked to investigate whether or not transiting exoplanets exist in the Pleiades star cluster.
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Bagheri, Fatemeh, Sedighe Sajadian, and Sohrab Rahvar. "Detection of exoplanet as a binary source of microlensing events in WFIRST survey." Monthly Notices of the Royal Astronomical Society 490, no. 2 (September 30, 2019): 1581–87. http://dx.doi.org/10.1093/mnras/stz2682.
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ABSTRACT We investigate the possibility of exoplanet detection orbiting source stars in microlensing events through WFIRST observations. We perform a Monte Carlo simulation on the detection rate of exoplanets via microlensing, assuming that each source star has at least one exoplanet. The exoplanet can reflect part of the light from the parent star or emit internal thermal radiation. In this new detection channel, we use microlensing as an amplifier to magnify the reflection light from the planet. In the literature, this mode of detecting exoplanets has been investigated much less than the usual mode in which the exoplanets are considered as one companion in binary-lens events. Assuming 72 d of observation per season with the cadence of 15 min, we find the probability of rocky planet detection with this method to be virtually zero. However, there is non-zero probability, for the detection of Jovian planets. We estimate the detection rates of the exoplanets by this method, using WFIRST observation to be $0.012{{\ \rm per\ cent}}$ in single-lens events and $0.9{{\ \rm per\ cent}}$ in the binary-lens events.
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Buslaeva, Elza, and Elena Belenkaya. "Characteristics of Multiplanetary Systems with One Host Star." Earth and Planetary Science 3, no. 2 (June 7, 2024): 1–13. http://dx.doi.org/10.36956/eps.v3i2.1025.
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The characteristics of 100 multiplanetary systems with single central stars of different spectral classes were examined. The data for these systems were taken from the NASA Exoplanet Archive. Among the systems, those were selected for which the exoplanet mass and radius were simultaneously known. For 293 planets from these systems masses, radii, orbital radii, orbital periods, and types of exoplanets were analyzed. It occurred that the rarest type in such systems were terrestrial planets and after them the gas giants. Most of the exoplanets belonged to the type of super-earths. The distribution of the number of planets in a system showed that systems with many exoplanets are less common than those with a smaller number. The system with the largest number of exoplanets in this sample is TRAPPIST-1 (7 planets systems). The properties of exoplanets in multiplanetary systems with one host star in terms of characteristics, orbital sizes, and number of planets, are investigated and compared with the Solar system. It turned out that the Solar system is rather an exception to the considered extrasolar multiplanetary systems.
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Elamin, Elsiddig Mohamed Ali. "Identifying Habitable Exoplanets Using the Earth and Cosmic Harmonic Factor." Hyperscience International Journals 3, no. 1 (March 2023): 1–4. http://dx.doi.org/10.55672/hij2023pp1-4.
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The search for habitable exoplanets has been an active area of research in astronomy for decades. In this study, we sought to identify exoplanets that may be suitable for life by comparing the resulting Planets to Star distance when applying the Earth & Cosmic Harmonic Factor for a sample of 5200 exoplanet candidates identified by NASA to that of Earth. After analyzing the data, we identified 5 exoplanets that had the Earth & Cosmic Harmonic Factor ratios within a range similar to that of Earth. Our findings suggest that these exoplanets may have conditions suitable for life and warrant further investigation.
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Jin, Yucheng, Lanyi Yang, and Chia-En Chiang. "Exoplanets Identification and Clustering with Machine Learning Methods." Machine Learning and Applications: An International Journal 9, no. 1 (March 31, 2022): 1–14. http://dx.doi.org/10.5121/mlaij.2022.9101.
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The discovery of habitable exoplanets has long been a heated topic in astronomy. Traditional methods for exoplanet identification include the wobble method, direct imaging, gravitational microlensing, etc., which not only require a considerable investment of manpower, time, and money, but also are limited by the performance of astronomical telescopes. In this study, we proposed the idea of using machine learning methods to identify exoplanets. We used the Kepler dataset collected by NASA from the Kepler Space Observatory to conduct supervised learning, which predicts the existence of exoplanet candidates as a three-categorical classification task, using decision tree, random forest, naïve Bayes, and neural network; we used another NASA dataset consisted of the confirmed exoplanets data to conduct unsupervised learning, which divides the confirmed exoplanets into different clusters, using k-means clustering. As a result, our models achieved accuracies of 99.06%, 92.11%, 88.50%, and 99.79%, respectively, in the supervised learning task and successfully obtained reasonable clusters in the unsupervised learning task.
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Chen, Wenda. "The Comparison of Five Methods of Detecting Exoplanets." Highlights in Science, Engineering and Technology 38 (March 16, 2023): 235–44. http://dx.doi.org/10.54097/hset.v38i.5812.
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Detecting exoplanets has become a hot topic, where various detection scenarios have been proposed. Five of these methods have all found more than 50 exoplanets, which are the transit method, the radial velocity method, the microlensing method, the imaging method, and the timing method. This paper aims to find their pros and cons, and the type of exoplanet that is suitable for each method by comparing the characteristics of exoplanets found by each method and the detection result of each method. The transit method is suitable for exoplanets with short periods possessing the advantages of measuring various parameters of exoplanets simultaneously, but can confuse exoplanets and other celestial bodies with the same radius of planets. The radial velocity method is best for exoplanets with small orbit radius or large mass, whereas it can only determine the minimum mass of exoplanets. The microlensing method can find exoplanets that are extremely far from the Earth or even rogue planets, as well as their mass. However, it does not allow researchers to observe the exoplanets found by it twice. The imaging method offers a tool to directly observe exoplanets in the infrared band. It can detect exoplanets that are extremely far from their host star with relatively high temperatures or rogue planets, but these are also the types of exoplanets that it can be detected. The timing method allows observers to discover exoplanets around pulsars, pulsating stars, eclipsing binaries, and planetary systems with discovered planets, but it is limited to these types.
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Tsurikov, G. N., and D. V. Bisikalo. "NO BIOMARKER: TRANSMISSION AND EMISSION METHODS FOR ITS POTENTIAL DETECTION IN EXOPLANET ATMOSPHERES WITH SPEKTR-UF (WSO-UV)." Астрономический журнал 100, no. 11 (November 1, 2023): 987–1004. http://dx.doi.org/10.31857/s0004629923110105.
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Among all habitability factors for terrestrial exoplanets, one of the most important is the presence of a secondary N2–O2 dominant atmosphere in an exoplanet. This factor can potentially indicate the already existing geological and biological processes on the exoplanet. Meanwhile, direct characterization of the N2–O2 atmospheres of terrestrial exoplanets is a difficult observational task. There are only a few indicators (molecules) of such an atmosphere, among which one can single out a potential biomarker – a molecule of nitric oxide NO. The strongest spectral features of this molecule in the ultraviolet range are γ-bands (203–248 nm). An important role in the search for potential biomarkers on exoplanets, including the registration of NO γ‑bands, can be played by planned for the launch WSO-UV space observatory. In the paper estimates of the possibility of detecting the transmission of light in γ-bands in the atmospheres of exoplanets with this observatory are presented. The methods of emission and transmission spectroscopy are compared as applied to the detection of NO. Based on the results of this work, it is shown that there is a potential possibility of detecting a transmission signal in the NO γ-bands in the atmospheres of nearby exoplanets (10 pc) using the LSS spectrograph of the WSO-UV observatory. At the same time, the imposed restrictions for the registration of this signal on more distant exoplanets are presented.
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Ballmer, Maxim D., and Lena Noack. "The Diversity of Exoplanets: From Interior Dynamics to Surface Expressions." Elements 17, no. 4 (August 1, 2021): 245–50. http://dx.doi.org/10.2138/gselements.17.4.245.
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The coupled interior–atmosphere system of terrestrial exoplanets remains poorly understood. Exoplanets show a wide variety of sizes, densities, surface temperatures, and interior structures, with important knock-on effects for this coupled system. Many exoplanets are predicted to have a “stagnant lid” at the surface, with a rigid stationary crust, sluggish mantle convection, and only minor volcanism. However, if exoplanets have Earth-like plate tectonics, which involves several discrete, slowly moving plates and vigorous tectono-magmatic activity, then this may be critical for planetary habitability and have implications for the development (and evolution) of life in the galaxy. Here, we summarize our current knowledge of coupled planetary dynamics in the context of exoplanet diversity.
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Bernath, Peter F. "Molecular opacities for exoplanets." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372, no. 2014 (April 28, 2014): 20130087. http://dx.doi.org/10.1098/rsta.2013.0087.
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Spectroscopic observations of exoplanets are now possible by transit methods and direct emission. Spectroscopic requirements for exoplanets are reviewed based on existing measurements and model predictions for hot Jupiters and super-Earths. Molecular opacities needed to simulate astronomical observations can be obtained from laboratory measurements, ab initio calculations or a combination of the two approaches. This discussion article focuses mainly on laboratory measurements of hot molecules as needed for exoplanet spectroscopy.
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Bjorkman, Karen S. "Polarimetry of Binary Stars and Exoplanets." Proceedings of the International Astronomical Union 7, S282 (July 2011): 173–80. http://dx.doi.org/10.1017/s1743921311027281.
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AbstractPolarimetry is a useful diagnostic of asymmetries in both circumstellar environments and binary star systems. Its sensitivity to asymmetries in systems means that it can help to uncover details about system orbital parameters, including providing information about the orbital inclination. Polarimetry can probe the circumstellar and/or circumbinary material as well. A number of significant results on binary systems have been produced by polarimetric studies. One might therefore expect that polarimetry could similarly play a useful role in studies of exoplanets, and a number of possible diagnostics for exoplanets have been proposed. However, the application of polarimetry to exoplanet research is only in preliminary stages, and the difficulties with applying the technique to exoplanets are non-trivial. This review will discuss the successes of polarimetry in analyzing binary systems, and consider the possibilities and challenges for extending similar analysis to exoplanet systems.
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Putirka, Keith D., Caroline Dorn, Natalie R. Hinkel, and Cayman T. Unterborn. "Compositional Diversity of Rocky Exoplanets." Elements 17, no. 4 (August 1, 2021): 235–40. http://dx.doi.org/10.2138/gselements.17.4.235.
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To test whether exoplanets are similar to Earth, knowledge of their host star composition is essential. Stellar elemental abundances and planetary orbital data show that of the ~5,000 known minerals, exoplanetary silicate mantles contain mostly olivine, orthopyroxene, and clinopyroxene, ± quartz and magnesiowüstite at the extremes, while wholly exotic mineralogies are unlikely. Understanding the geology of exoplanets requires a better marriage of geological insights to astronomical data. The study of exoplanets is like a mirror: it reflects our incomplete understanding of Earth and neighboring planets. New geological/planetary experiments, informed by exoplanet studies, are needed for effective progress.
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Route, Matthew. "ROME. IV. An Arecibo Search for Substellar Magnetospheric Radio Emissions in Purported Exoplanet-hosting Systems at 5 GHz." Astrophysical Journal 966, no. 1 (April 25, 2024): 55. http://dx.doi.org/10.3847/1538-4357/ad30ff.
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Abstract Plasma flow–obstacle interactions, such as those between an exoplanet’s magnetosphere and the host star’s stellar wind, may lead to detectable radio emissions. Despite many attempts to detect magnetospheric (auroral) radio emissions from exoplanets, a reproducible, unambiguous detection remains elusive. This fourth paper of the Radio Observations of Magnetized Exoplanets (ROME) series presents the results of a targeted radio survey of nine nearby systems that host exoplanet, brown dwarf, or low-mass-stellar companions conducted with the Arecibo radio telescope at ∼5 GHz. This search for magnetospheric radio emissions has the greatest sensitivity (∼1 mJy during <1 s integration times) and collected full Stokes parameters over the largest simultaneous bandpass of any survey to date. It is also the first survey to search for radio emission from brown dwarfs of spectral class Y, which may illuminate open questions regarding their magnetism, interior and atmospheric structure, and formation histories. No magnetospheric radio emissions from substellar companions were detected. These results are examined within the context of recent theoretical work on plasma flow–obstacle interactions, and radio emissions observed from the solar system planets and ultracool dwarfs.
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Konatham, Samuel, Javier Martin-Torres, and Maria-Paz Zorzano. "Atmospheric composition of exoplanets based on the thermal escape of gases and implications for habitability." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 476, no. 2241 (September 2020): 20200148. http://dx.doi.org/10.1098/rspa.2020.0148.
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The detection of habitable exoplanets is an exciting scientific and technical challenge. Owing to the current and most likely long-lasting impossibility of performing in situ exploration of exoplanets, their study and hypotheses regarding their capability to host life will be based on the restricted low-resolution spatial and spectral information of their atmospheres. On the other hand, with the advent of the upcoming exoplanet survey missions and technological improvements, there is a need for preliminary discrimination that can prioritize potential candidates within the fast-growing list of exoplanets. Here we estimate, for the first time and using the kinetic theory of gases, a list of the possible atmospheric species that can be retained in the atmospheres of the known exoplanets. We conclude that, based on our current knowledge of the detected exoplanets, 45 of them are good candidates for habitability studies. These exoplanets could have Earth-like atmospheres and should be able to maintain stable liquid water. Our results suggest that the current definition of a habitable zone around a star should be revisited and that the capacity of the planet to host an Earth-like atmosphere to support the stability of liquid water should be added.
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Biller, Beth. "Detecting and Characterizing Exoplanets with Direct Imaging: Past, Present, and Future." Proceedings of the International Astronomical Union 8, S299 (June 2013): 1–11. http://dx.doi.org/10.1017/s1743921313007667.
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AbstractThe last decade has yielded the first images of exoplanets, considerably advancing our understanding of the properties of young giant planets. In this talk I will discuss current results from ongoing direct imaging efforts as well as future prospects for detection and characterization of exoplanets via high contrast imaging. Direct detection, and direct spectroscopy in particular, have great potential for advancing our understanding of extrasolar planets. In combination with other methods of planet detection, direct imaging and spectroscopy will allow us to eventually: 1) study the physical properties of exoplanets (colors, temperatures, etc.) in depth and 2) fully map out the architecture of typical planetary systems. Direct imaging has offered us the first glimpse into the atmospheric properties of young high-mass (3-10 MJup) exoplanets. Deep direct imaging surveys for exoplanets have also yielded the strongest constraints to date on the statistical properties of wide giant exoplanets. A number of extremely high contrast exoplanet imaging instruments have recently come online or will come online within the next year (including Project 1640, SCExAO, SPHERE, GPI, among others). I will discuss future prospects with these instruments.
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Kalra, Preeti, Abhendra PratapSingh, Arushi Gupt, Kartik Gupta, and Prachi Jindal. "A study on unveiling the secrets of exoplanet hunting." International Journal of Research in Engineering and Innovation 08, no. 01 (2024): 10–15. http://dx.doi.org/10.36037/ijrei.2024.8102.
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Exoplanets are celestial bodies outside our solar system, orbiting stars other than our sun. They come in various sizes, compositions, and distances from their host stars. Scientists detect exoplanets by observing the dimming of a star's light as a planet passes in front of it (transit method), measuring the gravitational tug a planet exerts on its star (radial velocity method), or directly capturing their images. Studying exoplanets is a captivating area of astronomy that unveils our universe's vast array of planetary systems. Researchers delve into these distant worlds to explore their atmospheres, structures, and potential habitability, aiming to gather insights into the likelihood of life existing beyond our solar system. This paper addresses the challenges of distinguishing exoplanet signals from stellar activity, instrumental noise, and other astrophysical phenomena. It discusses the role of data-driven approaches, machine learning, and advanced statistical analyses in enhancing the reliability and accuracy of exoplanet detections after applying KNN.
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Wang, Junyi. "Exoplanet Radio Emission Detection: Principles and Approaches." Highlights in Science, Engineering and Technology 72 (December 15, 2023): 77–82. http://dx.doi.org/10.54097/bcphhk88.
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Radio astronomy has emerged as a promising avenue for the detection and characterization of exoplanets, offering unique insights into the physical and atmospheric properties of these distant celestial bodies. This study commences with a historical overview of the early works by Zarka that laid the groundwork for the systematic exploration of radio exoplanet detection. It analyzes the theoretical principles and mechanisms that underpin the generation of radio emissions from exoplanetary systems. Detailed analysis delves into the specific instrumental capabilities of LOFAR, nenuFAR, and FAST, elucidating their respective strengths and limitations in detecting exoplanetary radio signals. In particular, the review points out the sensitivity and frequency coverage of each telescope and their potential to characterize a diverse range of exoplanets. Finally, this paper discusses the future prospects and potential synergies in advancing exoplanet radio detection. It concludes with an outlook on the role of radio astronomy in the exploration of exoplanetary systems and the exciting possibilities that lie ahead in understanding the diversity of exoplanets in the universe.
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Faedi, Francesca, Susana C. C. Barros, Don Pollacco, Elaine K. Simpson, James McCormac, Victoria Moulds, Chris Watson, et al. "New transiting exoplanets from the SuperWASP-North survey." Proceedings of the International Astronomical Union 6, S276 (October 2010): 143–47. http://dx.doi.org/10.1017/s1743921311020084.
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AbstractThe Wide Angle Search for Planet (WASP) project is one of the leading projects in the discovery of transiting exoplanets. We present 1) the current status of the WASP-North survey, 2) our recent exoplanet discoveries, and 3) we exemplify how these results fit into our understanding of transiting exoplanet properties and how they can help to understand exoplanet diversity.
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Green, D. A., and N. Madhusudhan. "Search for radio emission from the exoplanets Qatar-1b and WASP-80b near 150 MHz using the giant metrewave radio telescope." Monthly Notices of the Royal Astronomical Society 500, no. 1 (October 15, 2020): 211–14. http://dx.doi.org/10.1093/mnras/staa3208.
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ABSTRACT We present radio observations made towards the exoplanets Qatar-1b and WASP-80b near 150 MHz with the Giant Meterwave Radio Telescope (GMRT). These targets are relatively nearby irradiated giant exoplanets, a hot Jupiter and a hot Saturn, with sizes comparable to Jupiter but different masses and lower densities. Both the targets are expected to host extended H/He envelopes like Jupiter, with comparable or larger magnetic moments. No radio emission was detected from these exoplanets, with 3σ limits of 5.9 and 5.2 mJy for Qatar-1b and WASP-80b, respectively, from these targeted observations. These are considerably deeper limits than those available for exoplanets from wide-field surveys at similar frequencies. We also present archival Very Large Array (VLA) observations of a previously reported radio source close to 61 Vir (which has three exoplanets). The VLA observations resolve the source, which we identify as an extragalactic radio source, i.e. a chance association with 61 Vir. Additionally, we cross-match a recent exoplanet catalogue with the TIFR GMRT Sky Survey ADR1 radio catalogue, but do not find any convincing associations.
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Li, Jiazheng, Jonathan H. Jiang, Huanzhou Yang, Dorian S. Abbot, Renyu Hu, Thaddeus D. Komacek, Stuart J. Bartlett, and Yuk L. Yung. "Rotation Period Detection for Earth-like Exoplanets." Astronomical Journal 163, no. 1 (December 21, 2021): 27. http://dx.doi.org/10.3847/1538-3881/ac36ce.
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Abstract A terrestrial planet’s rotation period is one of the key parameters that determines its climate and habitability. Current methods for detecting the rotation period of exoplanets are not suitable for terrestrial exoplanets. Here we demonstrate that, under certain conditions, the rotation period of an Earth-like exoplanet will be detectable using direct-imaging techniques. We use a global climate model that includes clouds to simulate reflected starlight from an Earth-like exoplanet and explore how different parameters (e.g., orbital geometry, wavelength, time resolution) influence the detectability of the planet’s rotation period. We show that the rotation period of an Earth-like exoplanet is detectable using visible-wavelength channels with time-series monitoring at a signal-to-noise ratio (S/N) >20 with ∼5–15 rotation periods of data, while the rotation period of a planet with full ocean coverage is unlikely to be detectable. To better detect the rotation period, one needs to plan the observation so that each individual integration would yield a S/N >10, while keeping the integration time shorter than 1/6 to 1/4 of the rotation period of the planet. Our results provide important guidance for rotation period detection of Earth-like exoplanets in reflected light using future space telescopes.
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Komacek, Thaddeus D., Wanying Kang, Jacob Lustig-Yaeger, and Stephanie L. Olson. "Constraining the Climates of Rocky Exoplanets." Elements 17, no. 4 (August 1, 2021): 251–56. http://dx.doi.org/10.2138/gselements.17.4.251.
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Numerical climate models originally developed for Earth have been adapted to study exoplanetary climates. This is allowing us to investigate the range of properties that might affect an exoplanet’s climate. The recent discovery, and upcoming characterization, of cosmically close rocky exoplanets opens the door toward understanding the processes that shape planetary climates, maybe also leading to insight into the persistent habitability of Earth itself. We summarize the recent advances made in understanding the climate of rocky exoplanets, including their atmospheric structure, chemistry, evolution, and atmospheric and oceanic circulation. We describe current and upcoming astronomical observations that will constrain the climate of rocky exoplanets and describe how modeling tools will both inform and interpret future observations.
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Piette, Anjali A. A., Nikku Madhusudhan, and Avi M. Mandell. "HyDRo: atmospheric retrieval of rocky exoplanets in thermal emission." Monthly Notices of the Royal Astronomical Society 511, no. 2 (December 11, 2021): 2565–84. http://dx.doi.org/10.1093/mnras/stab3612.
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ABSTRACT Emission spectroscopy is a promising technique to observe atmospheres of rocky exoplanets, probing both their chemistry and thermal profiles. We present hydro, an atmospheric retrieval framework for thermal emission spectra of rocky exoplanets. hydro does not make prior assumptions about the background atmospheric composition, and can therefore be used to interpret spectra of secondary atmospheres with unknown compositions. We use hydro to assess the chemical constraints which can be placed on rocky exoplanet atmospheres using JWST. First, we identify the best currently known rocky exoplanet candidates for spectroscopic observations in thermal emission with JWST, finding >30 known rocky exoplanets whose thermal emission will be detectable by JWST/MIRI in fewer than 10 eclipses at R ∼ 10. We then consider the observations required to characterize the atmospheres of three promising rocky exoplanets across the ∼400–800 K equilibrium temperature range: Trappist-1 b, GJ 1132 b, and LHS 3844 b. Considering a range of CO2- to H2O-rich atmospheric compositions, we find that as few as eight eclipses of LHS 3844 b or GJ 1132 b with MIRI LRS will be able to place important constraints on the chemical compositions of their atmospheres. This includes confident detections of CO2 and H2O in the case of a cloud-free CO2-rich composition, besides ruling out a bare rock scenario. Similarly, 30 eclipses of Trappist-1 b with MIRI LRS can allow detections of a cloud-free CO2-rich or CO2-H2O atmosphere. hydro will allow important atmospheric constraints for rocky exoplanets using JWST observations, providing clues about their geochemical environments.
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Simpson, Emilie R., Tara Fetherolf, Stephen R. Kane, Joshua Pepper, Teo Močnik, and Paul A. Dalba. "Variability of Known Exoplanet Host Stars Observed by TESS." Astronomical Journal 166, no. 2 (July 20, 2023): 72. http://dx.doi.org/10.3847/1538-3881/acda26.
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Abstract Both direct and indirect methods of exoplanet detection rely upon detailed knowledge of the potential host stars. Such stellar characterization allows for accurate extraction of planetary properties, as well as contributing to our overall understanding of exoplanetary system architecture. In this analysis, we examine the photometry of 264 known exoplanet host stars (harboring 337 planetary companions) that were observed during the Transiting Exoplanet Survey Satellite (TESS) Prime Mission. We identify periodic signatures in the lightcurves of these stars and make possible connections to stellar pulsations and their rotation periods, and compare the stellar variability to the published planetary orbital periods. From these comparisons, we quantify the effects of stellar variability on exoplanet detection, confirming that exoplanets detection is biased toward lower variability stars, but larger exoplanets dominate the population of exoplanets around variable stars. Exoplanet detection methods represented among these systems are distinct between stellar spectral types across the main sequence, though notable outliers exist. In addition, biases present in both the sourced data from TESS and the host star selection process, which strongly influences the representation of both stellar and planetary characteristics in the final populations. We also determine whether the host stars photometric variability affects or mimics the behavior or properties of the system’s planets. These results are discussed in the context of how the behavior of the host star is responsible for how we observe exoplanet characteristics, most notably their radii and atmospheric properties, and how the activity may alter our measurements or impact the evolution of planetary properties.
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Rodríguez-Mozos, J. M., and A. Moya. "Erosion of an exoplanetary atmosphere caused by stellar winds." Astronomy & Astrophysics 630 (September 23, 2019): A52. http://dx.doi.org/10.1051/0004-6361/201935543.
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Aims. We present a formalism for a first-order estimation of the magnetosphere radius of exoplanets orbiting stars in the range from 0.08 to 1.3 M⊙. With this radius, we estimate the atmospheric surface that is not protected from stellar winds. We have analyzed this unprotected surface for the most extreme environment for exoplanets: GKM-type and very low-mass stars at the two limits of the habitable zone. The estimated unprotected surface makes it possible to define a likelihood for an exoplanet to retain its atmosphere. This function can be incorporated into the new habitability index SEPHI. Methods. Using different formulations in the literature in addition to stellar and exoplanet physical characteristics, we estimated the stellar magnetic induction, the main characteristics of the stellar wind, and the different star-planet interaction regions (sub- and super-Alfvénic, sub- and supersonic). With this information, we can estimate the radius of the exoplanet magnetopause and thus the exoplanet unprotected surface. Results. We have conducted a study of the auroral aperture angles for Earth-like exoplanets orbiting the habitable zone of its star, and found different behaviors depending on whether the star is in rotational saturated or unsaturated regimes, with angles of aperture of the auroral ring above or below 36°, respectively, and with different slopes for the linear relation between the auroral aperture angle at the inner edge of the habitable zone versus the difference between auroral aperture angles at the two boundaries of the habitable zone. When the planet is tidally locked, the unprotected angle increases dramatically to values higher than 40° with a low likelihood of keeping its atmosphere. When the impact of stellar wind is produced in the sub-Alfvénic regime, the likelihood of keeping the atmosphere is almost zero for exoplanets orbiting very close to their star, regardless of whether they are saturated or not.
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Bennett, David P., Clément Ranc, and Rachel B. Fernandes. "No Sub-Saturn-mass Planet Desert in the CORALIE/HARPS Radial-velocity Sample." Astronomical Journal 162, no. 6 (November 16, 2021): 243. http://dx.doi.org/10.3847/1538-3881/ac2a2b.
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Abstract We analyze the CORALIE/HARPS sample of exoplanets found by the Doppler radial-velocity method for signs of the predicted gap or “desert” at 10–100 M ⊕ caused by runaway gas accretion at semimajor axes of <3 au. We find that these data are not consistent with this prediction. This result is similar to the finding by the MOA gravitational microlensing survey that found no desert in the exoplanet distribution for exoplanets in slightly longer period orbits and somewhat lower host masses (Suzuki et al. 2018). Together, these results imply that the runaway gas accretion scenario of the core accretion theory does not have a large influence on the final mass and semimajor axis distribution of exoplanets.
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Mistry, Priyashkumar, Kamlesh Pathak, Aniket Prasad, Georgios Lekkas, Surendra Bhattarai, Sarvesh Gharat, Mousam Maity, et al. "VaTEST. II. Statistical Validation of 11 TESS-detected Exoplanets Orbiting K-type Stars." Astronomical Journal 166, no. 1 (June 12, 2023): 9. http://dx.doi.org/10.3847/1538-3881/acd548.
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Abstract NASA’s Transiting Exoplanet Survey Satellite (TESS) is an all-sky survey mission designed to find transiting exoplanets orbiting nearby bright stars. It has identified more than 329 transiting exoplanets, and almost 6000 candidates remain unvalidated. In this manuscript, we discuss the findings from the ongoing Validation of Transiting Exoplanets using Statistical Tools (VaTEST) project, which aims to validate new exoplanets for further characterization. We validated 11 new exoplanets by examining the light curves of 24 candidates using the LATTE and TESS-Plot tools and computing the false-positive probabilities using the statistical validation tool TRICERATOPS. These include planets suitable for atmospheric characterization using transmission spectroscopy (TOI-2194b), emission spectroscopy (TOI-3082b and TOI-5704b) and for both transmission and emission spectroscopy (TOI-672b, TOI-1694b, and TOI-2443b). Our validated planets have one super-Earth (TOI-2194b) orbiting a bright (V = 8.42 mag), metal-poor ([Fe/H] = −0.3720 ± 0.1) star, and one short-period Neptune-like planet (TOI-5704) in the hot-Neptune desert. In total, we validated one super-Earth, seven sub-Neptunes, one Neptune-like, and two sub-Saturn or super-Neptune-like exoplanets. Additionally, we identify five likely planet candidates (TOI-323, TOI-1180, TOI-2200, TOI-2408, and TOI-3913), which can be further studied to establish their planetary nature.
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Jiang, Jonathan, Daniel Zhao, Xuan Ji, Bohan Xie, and Kristen Fahy. "Revisiting the Planet Mass and Stellar Metallicity Relation for Low-Mass Exoplanets Orbiting GKM Class Stars." Universe 7, no. 4 (April 2, 2021): 88. http://dx.doi.org/10.3390/universe7040088.
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The growing database of exoplanets has shown us the statistical characteristics of various exoplanet populations, providing insight towards their origins. Observational evidence suggests that the process by which gas giants are conceived in the stellar disk may be disparate from that of smaller planets. Using NASA’s Exoplanet Archive, we analyzed the relationships between planet mass and stellar metallicity, as well as planet mass and stellar mass for low-mass exoplanets (MP < 0.13 MJ) orbiting spectral class G, K, and M stars. We performed further uncertainty analysis to confirm that the exponential law relationships found between the planet mass, stellar mass, and the stellar metallicity cannot be fully explained by observation biases alone.
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Owen, James E. "Atmospheric Escape and the Evolution of Close-In Exoplanets." Annual Review of Earth and Planetary Sciences 47, no. 1 (May 30, 2019): 67–90. http://dx.doi.org/10.1146/annurev-earth-053018-060246.
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Exoplanets with substantial hydrogen/helium atmospheres have been discovered in abundance, many residing extremely close to their parent stars. The extreme irradiation levels that these atmospheres experience cause them to undergo hydrodynamic atmospheric escape. Ongoing atmospheric escape has been observed to be occurring in a few nearby exoplanet systems through transit spectroscopy both for hot Jupiters and for lower-mass super-Earths and mini-Neptunes. Detailed hydrodynamic calculations that incorporate radiative transfer and ionization chemistry are now common in one-dimensional models, and multidimensional calculations that incorporate magnetic fields and interactions with the interstellar environment are cutting edge. However, comparison between simulations and observations remains very limited. While hot Jupiters experience atmospheric escape, the mass-loss rates are not high enough to affect their evolution. However, for lower-mass planets, atmospheric escape drives and controls their evolution, sculpting the exoplanet population that we observe today. ▪ Observations of some exoplanets have detected atmospheric escape driven by hydrodynamic outflows, causing the exoplanets to lose mass over time. ▪ Hydrodynamic simulations of atmospheric escape are approaching the sophistication required to compare them directly to observations. ▪ Atmospheric escape sculpts sharp features into the exoplanet population that we can observe today; these features have recently been detected.
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Nagler, Peter C., Billy Edwards, Brian Kilpatrick, Nikole K. Lewis, Pierre Maxted, C. Barth Netterfield, Vivien Parmentier, et al. "Observing Exoplanets in the Near-Infrared from a High Altitude Balloon Platform." Journal of Astronomical Instrumentation 08, no. 03 (September 2019): 1950011. http://dx.doi.org/10.1142/s2251171719500119.
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Although there exists a large sample of known exoplanets, little data exists that can be used to study their global atmospheric properties. This deficiency can be addressed by performing phase-resolved spectroscopy — continuous spectroscopic observations of a planet’s entire orbit about its host star — of transiting exoplanets. Planets with characteristics suitable for atmospheric characterization have orbits of several days, thus phase curve observations are highly resource intensive, especially for shared use facilities. In this work, we show that an infrared spectrograph operating from a high altitude balloon platform can perform phase-resolved spectroscopy of hot Jupiter-type exoplanets with performance comparable to a space-based telescope. Using the EXoplanet Climate Infrared TElescope (EXCITE) experiment as an example, we quantify the impact of the most important systematic effects that we expect to encounter from a balloon platform. We show an instrument like EXCITE will have the stability and sensitivity to significantly advance our understanding of exoplanet atmospheres. Such an instrument will both complement and serve as a critical bridge between current and future space-based near-infrared spectroscopic instruments.
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Otegi, J. F., F. Bouchy, and R. Helled. "Revisited mass-radius relations for exoplanets below 120 M⊕." Astronomy & Astrophysics 634 (February 2020): A43. http://dx.doi.org/10.1051/0004-6361/201936482.
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The masses and radii of exoplanets are fundamental quantities needed for their characterisation. Studying the different populations of exoplanets is important for understanding the demographics of the different planetary types, which can then be linked to planetary formation and evolution. We present an updated exoplanet catalogue based on reliable, robust, and, as much as possible accurate mass and radius measurements of transiting planets up to 120 M⊕. The resulting mass-radius (M-R) diagram shows two distinct populations, corresponding to rocky and volatile-rich exoplanets which overlap in both mass and radius. The rocky exoplanet population shows a relatively small density variability and ends at mass of ~25 M⊕, possibly indicating the maximum core mass that can be formed. We use the composition line of pure water to separate the two populations, and infer two new empirical M-R relations based on this data: M = (0.9 ± 0.06) R(3.45±0.12) for the rocky population, and M = (1.74 ± 0.38) R(1.58±0.10) for the volatile-rich population. While our results for the two regimes are in agreement with previous studies, the new M-R relations better match the population in the transition region from rocky to volatile-rich exoplanets, which correspond to a mass range of 5–25 M⊕, and a radius range of 2–3 R⊕.
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Carrión-González, Ó., A. García Muñoz, N. C. Santos, J. Cabrera, Sz Csizmadia, and H. Rauer. "Catalogue of exoplanets accessible in reflected starlight to the Nancy Grace Roman Space Telescope." Astronomy & Astrophysics 651 (July 2021): A7. http://dx.doi.org/10.1051/0004-6361/202039993.
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Context. Reflected starlight measurements will open a new path in the characterization of directly imaged exoplanets. However, we still lack a population study of known targets to which this technique can be applied. Aims. We investigate which of the about 4300 exoplanets confirmed to date are accessible for the Roman Space Telescope coronagraph in reflected starlight at reference wavelengths λ = 575, 730, and 825 nm. We carry out a population study and also address the prospects for phase-curve measurements. Methods. We used the NASA Exoplanet Archive as a reference for planet and star properties and explored the effect of their uncertainties on the exoplanet detectability by applying statistical arguments. We defined a planet as Roman-accessible on the basis of the inner and outer working angles of the instrument and its minimum planet-to-star contrast (IWA, OWA, and Cmin). We adopted three plausible configurations for these technical specifications, labeled pessimistic, intermediate, and optimistic. Our key outputs for each exoplanet are its probability of being Roman-accessible (Paccess), the range of observable phase angles, the evolution of its equilibrium temperature, the number of days per orbit for which it is accessible, and its transit probability. Results. In the optimistic scenario, we find 26 Roman-accessible exoplanets with Paccess > 25% and host stars brighter than V = 7 mag. This population is biased towards planets more massive than Jupiter, but also includes the super-Earths tau Cet e and f, which orbit near the habitable zone of their star. Thirteen planets are part of multi-planetary systems. Three of these planets have known transiting companions, which offers opportunities for a contemporaneous atmospheric characterization. The intermediate and pessimistic scenarios yield ten and three Roman-accessible exoplanets, respectively. We find that inclination estimates (e.g. with astrometry) are required to refine the detectability prospects. Conclusions. A science phase of the coronagraph instrument has a remarkable potential for characterizing the atmospheres of exoplanets that cannot be studied with other techniques.
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Kashyap Jagadeesh, Madhu, Sagarika Rao Valluri, Vani Kari, Katarzyna Kubska, and Łukasz Kaczmarek. "Indexing Exoplanets with Physical Conditions Potentially Suitable for Rock-Dependent Extremophiles." Life 10, no. 2 (January 26, 2020): 10. http://dx.doi.org/10.3390/life10020010.
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The search for different life forms elsewhere in the universe is a fascinating area of research in astrophysics and astrobiology. Currently, according to the NASA Exoplanet Archive database, 3876 exoplanets have been discovered. The Earth Similarity Index (ESI) is defined as the geometric mean of radius, density, escape velocity, and surface temperature and ranges from 0 (dissimilar to Earth) to 1 (similar to Earth). The ESI was created to index exoplanets on the basis of their similarity to Earth. In this paper, we examined rocky exoplanets whose physical conditions are potentially suitable for the survival of rock-dependent extremophiles, such as the cyanobacteria Chroococcidiopsis and the lichen Acarospora. The Rock Similarity Index (RSI) is first introduced and then applied to 1659 rocky exoplanets. The RSI represents a measure for Earth-like planets on which physical conditions are potentially suitable for rocky extremophiles that can survive in Earth-like extreme habitats (i.e., hot deserts and cold, frozen lands).
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Liu, Kunyang. "Studying the Exoplanets HAT-P-56 b and HATS-36 b with Kepler." Highlights in Science, Engineering and Technology 38 (March 16, 2023): 97–106. http://dx.doi.org/10.54097/hset.v38i.5746.
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Exoplanet has become one of the most popular research subjects in astronomy. This study analyzes light curve data from the K2 mission of the Kepler space telescope and measure the properties of two exoplanets, HAT-P-56 b and HATS-36 b. With the transit method, the radii are obtained, orbital periods and semi-major axes of these two exoplanets. For HAT-P-56 b, the period is , the radius is and the semi-major axis is . For HATS-36 b, the period is , the radius is and the semi-major axis is . Compared to previous studies, it is found that radii and semi-major axes measured in this paper are consistent with their results, whereas the calculated orbital period is a bit bigger. In addition, the large radii and short orbital periods suggest that both exoplanets are Hot Jupiters. These results shed light on the exploring of the exoplanets around the two host stars, HAT-P-56 and HATS-36.
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Lin, Zifan, Sara Seager, Sukrit Ranjan, Thea Kozakis, and Lisa Kaltenegger. "H2-dominated Atmosphere as an Indicator of Second-generation Rocky White Dwarf Exoplanets." Astrophysical Journal Letters 925, no. 1 (January 1, 2022): L10. http://dx.doi.org/10.3847/2041-8213/ac4788.
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Abstract Following the discovery of the first exoplanet candidate transiting a white dwarf (WD), a “white dwarf opportunity” for characterizing the atmospheres of terrestrial exoplanets around WDs is emerging. Large planet-to-star size ratios and hence large transit depths make transiting WD exoplanets favorable targets for transmission spectroscopy; conclusive detection of spectral features on an Earth-like planet transiting a close-by WD can be achieved within a medium James Webb Space Telescope program. Despite the apparently promising opportunity, however, the post-main sequence evolutionary history of a first-generation WD exoplanet has never been incorporated in atmospheric modeling. Furthermore, second-generation planets formed in WD debris disks have never been studied from a photochemical perspective. We demonstrate that transmission spectroscopy can identify a second-generation rocky WD exoplanet with a thick (∼1 bar) H2-dominated atmosphere. In addition, we can infer outgassing activities of a WD exoplanet based on its transmission spectra and test photochemical runaway by studying CH4 buildup.
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Liu, Zhiling. "C/O Ratio Studies in the atmosphere of hot Jupiters." Journal of Physics: Conference Series 2669, no. 1 (December 1, 2023): 012001. http://dx.doi.org/10.1088/1742-6596/2669/1/012001.
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Abstract Exoplanet atmospheres are a window into the chemical composition, internal motion and evolution of extrasolar planets. In the past two decades, more than 5,700 exoplanets have been discovered. The theoretical research and observation of exoplanet atmospheres have developed rapidly. Among the varieties of exoplanets, hot Jupiters are excellent objects for transit observation due to their characteristics of large radius, high temperature and close-in orbit, which provide many valuable research samples for spectroscopy. A large number of observations and studies have been carried out around it. With the rapid development of exoplanet atmospheres studies, this paper aims to provide a brief introduction on the detection methods of planetary atmospheres and the relevant research progress of the carbon-to-oxygen ratio (C/O) of hot Jupiters, which is an important property that reveals the atmospheric processes and planetary evolution, so as to show the prospect of the future study of exoplanet atmospheres.
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Yang, Chang. "Analysis and Comparison of Three Exoplanet Searching Schemes." Highlights in Science, Engineering and Technology 88 (March 29, 2024): 914–21. http://dx.doi.org/10.54097/hdw3ng92.
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In retrospect, from ancient times to the present, human beings have never stopped exploring the secrets of the universe. With this in mind, exploring the universe means the progress of human science and technology, promoting the exchange and integration of human civilization and avoiding unknown risks and continuing human civilization. In the 1990s, humans officially launched the challenge to detect exoplanets. Since then, research on exoplanet detection has developed rapidly. On this basis, this study introduces the research history, development status and research results of exoplanet detection, comprehensively introduces mainstream exoplanet detection methods and representative projects, and elaborates on the principles, instruments, and research results of the three most widely used methods. Finally, this study summarizes the current problems and difficulties that restrict the development of exoplanets, and look forward to the development trends and bright prospects of future planetary exploration. These results provide guiding insights of further exploration of exoplanet searching.
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Dymont, Austin H., Xinting Yu, Kazumasa Ohno, Xi Zhang, Jonathan J. Fortney, Daniel Thorngren, and Connor Dickinson. "Cleaning Our Hazy Lens: Exploring Trends in Transmission Spectra of Warm Exoplanets." Astrophysical Journal 937, no. 2 (September 30, 2022): 90. http://dx.doi.org/10.3847/1538-4357/ac7f40.
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Abstract Relatively little is understood about the atmospheric composition of temperate to warm exoplanets (equilibrium temperature T eq < 1000 K), as many of them are found to have uncharacteristically flat transmission spectra. Their flattened spectra are likely due to atmospheric opacity sources such as planet-wide photochemical hazes and condensation clouds. We compile the transmission spectra of 25 warm exoplanets previously observed by the Hubble Space Telescope and quantify the haziness of each exoplanet using a normalized amplitude of the water absorption feature (A H). By examining the relationships between A H and various planetary and stellar forcing parameters, we endeavor to find correlations of haziness associated with planetary properties. We adopt new statistical correlation tests that are more suitable for the small, nonnormally distributed warm exoplanet sample. Our analysis shows that none of the parameters have a statistically significant correlation with A H (p ≤ 0.01) with the addition of new exoplanet data, including the previously identified linear trends between A H and T eq or the hydrogen–helium envelope mass fraction (f HHe). This suggests that haziness in warm exoplanets is not simply controlled by any single planetary/stellar parameter. Among all the parameters we investigated, planet gravity (g p), atmospheric scale height (H), planet density (ρ p), orbital eccentricity (e), and age of the star (t age) have tentative correlations with A H. Specifically, lower H, higher g p, ρ p, e, or t age may lead to clearer atmospheres. We still need more observations and laboratory experiments to fully understand the complex physics and chemistry involved in creating hazy warm exoplanets.
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Hatzes, Artie P. "A European Roadmap for exoplanets." Proceedings of the International Astronomical Union 6, S276 (October 2010): 316–23. http://dx.doi.org/10.1017/s1743921311020382.
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AbstractThe Exoplanet Roadmap Advisory Team (EPR-AT) was formed by the European Space Agency (ESA) to advise it on the best path for characterizing exoplanets including terrestrial planets. The EPR-AT delivered its report to ESA in August 2010. Here we summarize the findings of this task force.
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Carter, Jennifer L. "Analysis of Thermal Emissions of Exoplanets with Axially Symmetric Temperature Gradients." Astrophysical Journal 939, no. 2 (November 1, 2022): 79. http://dx.doi.org/10.3847/1538-4357/ac9381.
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Abstract Here a new method of modeling the thermal emissions of exoplanets is described, in which the temperature gradient of an exoplanet is approximated by splitting it into N zones. First, we seek to determine how much this method differs from a simple dayside–nightside model used by previous researchers and found that the difference between the N-zone and the dayside–nightside models is greatest during the primary transit of the exoplanet, and for large temperature gradients. Next, we determine under what conditions EXONEST, a Bayesian inference software package, is able to correctly determine the model used to generate synthetic light-curve data. EXONEST is best able to determine the model used to generate synthetic data when the mass of the exoplanet is known, the added noise to the data is low, and the thermal emissions are large compared to the ellipsoidal variations. Finally, EXONEST was used to analyze photometric data for exoplanets Kepler-41b and Kepler-412b, and the dayside brightness temperatures were estimated to be 2574 ± 59 and 2496 ± 64 K, and those of the nightside were estimated to be 860 ± 316 and 874 ± 333 K for Kepler-41b and Kepler-412b, respectively. Finally, we found that the hottest zone for both planets was the zone nearest the terminator on the dayside of the exoplanet. This surprising result suggests that the model is better applied to exoplanets with little to no heat recirculation.
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Barstow, Joanna K. "The curse of clouds." Astronomy & Geophysics 62, no. 1 (February 1, 2021): 1.36–1.42. http://dx.doi.org/10.1093/astrogeo/atab044.
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Abstract Joanna K Barstow explores spectroscopic observations of transiting exoplanets, modelling their atmospheric clouds, and the forthcoming era of hot exoplanet research with the James Webb Space Telescope
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Donnelly, Shane, and Ayan Dutta. "Kepler Light Curve Classification Using Deep Learning and Markov Transition Field (Student Abstract)." Proceedings of the AAAI Conference on Artificial Intelligence 38, no. 21 (March 24, 2024): 23475–76. http://dx.doi.org/10.1609/aaai.v38i21.30435.
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An exoplanet is a planet, which is not a part of our solar system. Whether life exists in one or more of these exoplanets has fascinated humans for centuries. NASA’s Kepler Space Telescope has discovered more than 70% of known exoplanets in our universe. However, manually determining whether a Kepler light curve indicates an exoplanet or not becomes infeasible with the large volume of data. Due to this, we propose a deep learning-based strategy to automatically classify a Kepler light curve. More specifically, we first convert the light curve time series into its corresponding Markov Transition Field (MTF) image and then classify it. Results show that the accuracy of the proposed technique is 99.39%, which is higher than all current state-of-the-art approaches.