Article
Astronomy & Astrophysics
John B. Biersteker, Hilke E. Schlichting
Summary: The formation of the Solar system's terrestrial planets included a period of giant impacts, which could lead to significant volatile loss and changes in the planetary volatile inventory.
Research has shown that giant impacts during the formation of terrestrial planets can result in the efficient loss of H2O and other volatile species, potentially including oceans.
These findings suggest that the volatile budgets of terrestrial planets may be diverse due to various factors such as giant impacts and early atmospheric evolutionary processes.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Keavin Moore, Nicolas B. Cowan, Charles-Edouard Boukare
Summary: Earth-like planets orbiting M-dwarf stars are the best targets for finding signs of life. However, their habitability is threatened by water loss to space from high radiation flux. Research shows that a longer-lived surface magma ocean can help retain water, but it may also sequester significant water in the mantle, affecting surface habitability. Magma oceans and deep-water cycling can maintain or recover habitable surface conditions on these planets under certain conditions.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
A. Ambrifi, A. Balbi, M. Lingam, F. Tombesi, E. Perlman
Summary: This study investigates the impact of winds and outflows from active galactic nuclei (AGNs) on terrestrial planets in the Milky Way galaxy. By developing simple models, the authors estimate the maximum distance at which these effects become significant, finding that it may extend to around 1 kiloparsec.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
R. J. Ridgway, M. Zamyatina, N. J. Mayne, J. Manners, F. H. Lambert, M. Braam, B. Drummond, E. Hebrard, P. Palmer, K. Kohary
Summary: Stellar flares and coronal mass ejections from M dwarf stars have significant impacts on the habitability and atmospheric composition of terrestrial planets. This study used a general circulation model coupled with a photochemical kinetics scheme to examine the response of an Earth-like atmosphere to these events. The research found that stellar flares increase ozone levels in the atmosphere and coronal mass ejections generate potential bio-signatures. However, the changes in atmospheric composition also reduce the amount of harmful ultraviolet light reaching the planetary surface.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Environmental Sciences
Gordon L. Bjoraker, Michael H. Wong, Imke de Pater, Tilak Hewagama, Mate Adamkovics
Summary: By obtaining high-resolution spectra of Jupiter, we were able to analyze the spatial variation of NH3, H2O, and deep clouds on the planet. Our findings revealed significant variations in NH3 abundance in different latitudes and longitudes, as well as variations in the H2O abundance. This study provides important insights into the atmospheric structure and composition of Jupiter.
Article
Astronomy & Astrophysics
R. Pinotti, G. F. Porto de Mello
Summary: The study found that ocean salinity has a significant impact on the formation of land ice sheets. For planets with deep oceans and high salinity, the time needed to fill the Arctic land with ice sheets increases significantly, while for planets with shallow oceans, the negative feedback effect of high salinity helps delay the spread of ice sheets, counteracting other positive feedbacks. This phenomenon can be considered as a non-biological self-regulation mechanism that helps resist ice ages.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
P. Lavvas, A. Arfaux
Summary: The research investigates the impact of photochemical hazes and disequilibrium gases on the thermal structure of hot Jupiters, finding that the inclusion of photochemical hazes leads to significant heating of the upper atmosphere and cooling of the lower atmosphere. Various sulfur-containing species, as well as radicals produced by photochemistry, affect the thermal structure of the atmosphere. The study also highlights the importance of considering radiative feedback from photochemical hazes in general circulation models for a proper evaluation of atmospheric dynamics.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Mohamad Ali-Dib, Andrew Cumming, Douglas N. C. Lin
Summary: The study investigates the origins of cold sub-Saturns (CSSs) and suggests that they may emerge from giant collisions between sub-critical protoplanets, leading to the formation of CSS without transforming into gas giants. Results indicate that CSS could be more common than previously thought, and their formation is robust across various disc densities, grain opacities, and silicate abundances in the envelope.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Thomas Mikal-Evans
Summary: The study investigates the potential of using the James Webb Space Telescope to search for biosignatures in exoplanet atmospheres, finding that significant detections of CH4 and CO2 are possible with co-added transits using the Near Infrared Spectrograph, but more observations may be needed if cloud/haze layers are present.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Engin Keles
Summary: The study of exoplanet atmospheres reveals a large diversity compared to planets in our Solar system, with different kinds of Jupiter-type exoplanets showing varying wind speeds and atmospheric features. Through modeling the effect of winds on synthetic absorption lines, it is suggested that high wind velocities could explain the broadening of absorption lines observed in different planets. This could be influenced by atmospheric drag and ionization of alkali lines, affecting the existence of zonal jet streams on hot Jupiter and ultra-hot Jupiter differently.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
B. Charnay, D. Blain, B. Bezard, J. Leconte, M. Turbet, A. Falco
Summary: The study aims to understand the formation, distribution, and observational consequences of water clouds on K2-18b and other temperate sub-Neptunes. By simulating atmospheric dynamics, water cloud formation, and spectra using a 3D general circulation model, the study found that cloud distribution is highly sensitive to the concentration of cloud condensation nuclei and planetary rotation rate, with a modest impact on transit spectra in the near-infrared.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
L-K Dai, X. Zhang, J. Cui
Summary: The Venusian clouds are formed by the binary condensation of sulfuric acid and water vapor. A semi-analytical model was developed to explain the observed distribution of vapor and clouds on Venus. The model is faster and more accurate than previous models, making it important for studying the cloudy atmospheres of Venus and Venus-like exoplanets.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
F. Montmessin, O. Korablev, A. Trokhimovskiy, F. Lefevre, A. A. Fedorova, L. Baggio, A. Irbah, G. Lacombe, K. S. Olsen, A. S. Braude, D. A. Belyaev, J. Alday, F. Forget, F. Daerden, J. Pla-Garcia, S. Rafkin, C. F. Wilson, A. Patrakeev, A. Shakun, J. L. Bertaux
Summary: Efforts to detect methane in the Martian atmosphere have been hindered by dust interference, leading to upper limits on methane detections. While the absence of methane in TGO spectra contradicts previous detections by Curiosity, it also strengthens constraints on the mechanism explaining lower methane abundances.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Yutian Cao, Dandan Niu, Wenjun Liang, Jun Cui, Xiaoshu Wu, Xin Wan, Jiahao Zhong, Lei Li, Zhaojin Rong, Yong Wei
Summary: Thermal electron depression and energetic electron depletion are observed in the nightside Martian ionosphere. While energetic electron depletion has been extensively studied, there is limited research on thermal electron depression and the correlation between the two is unknown. Through Mars Express total electron content (TEC) measurements, a large number of TEC depression features are identified, with large amplitude depression being more frequently observed near strong magnetic fields and small amplitude depression uniformly distributed across the Martian surface.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
James E. Owen, Ruth A. Murray-Clay, Ethan Schreyer, Hilke E. Schlichting, David Ardila, Akash Gupta, R. O. Parke Loyd, Evgenya L. Shkolnik, David K. Sing, Mark R. Swain
Summary: Lyman alpha transits are a crucial tool for studying atmospheric escape processes of exoplanets, with the depth and duration providing insights into the velocity of planetary outflows.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Yuichi Ito, Quentin Changeat, Billy Edwards, Ahmed Al-Refaie, Giovanna Tinetti, Masahiro Ikoma
Summary: This study examines the detectability of atmospheres vaporised from magma oceans on dry, rocky Super-Earths orbiting very close to their host stars. The detection of vaporised rock atmospheres such as Na and SiO is believed to provide definitive evidence for rocky planets and could be potentially observed with planned space-based telescopes. However, challenging measurements exist due to small spectral signatures, especially for planets with irradiation temperature of 3000 K or hotter than 3500 K within a certain distance from Earth.
EXPERIMENTAL ASTRONOMY
(2022)
Article
Astronomy & Astrophysics
Yuichi Ito, Masahiro Ikoma
Summary: Recent studies show that photo-evaporation plays a significant role in the mass and composition of close-in low-mass planets, but there is limited investigation on rocky vapor atmospheres. Hydrodynamic simulations reveal that most of the X-ray and UV energy from the host star is lost through radiative emission of coolant gas species like Na and Mg. This suggests that for hot rocky exoplanets, the cooling efficiency of the mineral atmosphere may not greatly impact planetary mass and composition.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Yuhiko Aoyama, Gabriel-Dominique Marleau, Masahiro Ikoma, Christoph Mordasini
Summary: This research presents a theoretical L (acc)-L (H alpha) relationship applicable to a shock at the surface of a planet, highlighting the impact of accretion rates and masses on stellar radiation luminosity. It suggests that observed H alpha signals may simultaneously come from planetary surface shocks and accretion-funnel emission, with different emission scenarios applying in various accretion contexts.
ASTROPHYSICAL JOURNAL LETTERS
(2021)
Article
Astronomy & Astrophysics
Ravit Helled, Stephanie Werner, Caroline Dorn, Tristan Guillot, Masahiro Ikoma, Yuichi Ito, Mihkel Kama, Tim Lichtenberg, Yamila Miguel, Oliver Shorttle, Paul J. Tackley, Diana Valencia, Allona Vazan
Summary: The Ariel ESA mission aims to measure the atmospheric composition of exoplanets to better understand their bulk compositions. This will advance exoplanet characterisation and provide new insights into the nature of planets in our galaxy.
EXPERIMENTAL ASTRONOMY
(2022)
Article
Astronomy & Astrophysics
Ian Wong, Avi Shporer, George Zhou, Daniel Kitzmann, Thaddeus D. Komacek, Xianyu Tan, Rene Tronsgaard, Lars A. Buchhave, Shreyas Vissapragada, Michael Greklek-McKeon, Joseph E. Rodriguez, John P. Ahlers, Samuel N. Quinn, Elise Furlan, Steve B. Howell, Allyson Bieryla, Kevin Heng, Heather A. Knutson, Karen A. Collins, Kim K. McLeod, Perry Berlind, Peyton Brown, Michael L. Calkins, Jerome P. de Leon, Emma Esparza-Borges, Gilbert A. Esquerdo, Akihiko Fukui, Tianjun Gan, Eric Girardin, Crystal L. Gnilka, Masahiro Ikoma, Eric L. N. Jensen, John Kielkopf, Takanori Kodama, Seiya Kurita, Kathryn Lester, Pablo Lewin, Giuseppe Marino, Felipe Murgas, Norio Narita, Enric Palle, Richard P. Schwarz, Keivan G. Stassun, Motohide Tamura, Noriharu Watanabe, Bjorn Benneke, George R. Ricker, David W. Latham, Roland Vanderspek, Sara Seager, Joshua N. Winn, Jon M. Jenkins, Douglas A. Caldwell, William Fong, Chelsea X. Huang, Ismael Mireles, Joshua E. Schlieder, Bernie Shiao, Jesus Noel Villasenor
Summary: The discovery of an ultrahot Jupiter with a short orbital period is reported, with the planet's mass, radius, and temperature confirmed and the mass measured. The planetary system is well-aligned, with a deep secondary eclipse and a high radiative temperature.
ASTRONOMICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Shinsuke Takasao, Yuhiko Aoyama, Masahiro Ikoma
Summary: Observations have shown excess H alpha emission from young stellar systems like PDS 70. Models suggest that planetary accretion flows can produce this emission, but understanding the accretion process from shock-originated emission is challenging due to scale gaps. Combined simulations show that H alpha emission mainly occurs on localized areas on the protoplanetary surface, with weaker emission from accretion shocks above the CPD. The variability in accretion rate and H alpha luminosity of the protoplanet is influenced by fluctuating disk surface accretion layers.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Diego Turrini, Claudio Codella, Camilla Danielski, Davide Fedele, Sergio Fonte, Antonio Garufi, Mario Giuseppe Guarcello, Ravit Helled, Masahiro Ikoma, Mihkel Kama, Tadahiro Kimura, J. M. Diederik Kruijssen, Jesus Maldonado, Yamila Miguel, Sergio Molinari, Athanasia Nikolaou, Fabrizio Oliva, Olja Panic, Marco Pignatari, Linda Podio, Hans Rickman, Eugenio Schisano, Sho Shibata, Allona Vazan, Paulina Wolkenberg
Summary: The Ariel space mission aims to observe a diverse population of planets around different types of stars to collect information on their atmospheric compositions, advancing our understanding of planet formation. However, environmental and evolutionary factors can influence the final atmospheric composition. Ariel's characteristics make it optimally suited to address this complex problem.
EXPERIMENTAL ASTRONOMY
(2022)
Article
Astronomy & Astrophysics
Akihiko Fukui, Tadahiro Kimura, Teruyuki Hirano, Norio Narita, Takanori Kodama, Yasunori Hori, Masahiro Ikoma, Enric Palle, Felipe Murgas, Hannu Parviainen, Kiyoe Kawauchi, Mayuko Mori, Emma Esparza-Borges, Allyson Bieryla, Jonathan Irwin, Boris S. Safonov, Keivan G. Stassun, Leticia Alvarez-Hernandez, Victor J. S. Bejar, Nuria Casasayas-Barris, Guo Chen, Nicolas Crouzet, Jerome P. de Leon, Keisuke Isogai, Taiki Kagetani, Peter Klagyivik, Judith Korth, Seiya Kurita, Nobuhiko Kusakabe, John Livingston, Rafael Luque, Alberto Madrigal-Aguado, Giuseppe Morello, Taku Nishiumi, Jaume Orell-Miquel, Mahmoudreza Oshagh, Manuel Sanchez-Benavente, Monika Stangret, Yuka Terada, Noriharu Watanabe, Yujie Zou, Motohide Tamura, Takashi Kurokawa, Masayuki Kuzuhara, Jun Nishikawa, Masashi Omiya, Sebastien Vievard, Akitoshi Ueda, David W. Latham, Samuel N. Quinn, Ivan S. Strakhov, Alexandr A. Belinski, Jon M. Jenkins, George R. Ricker, Sara Seager, Roland Vanderspek, Joshua N. Winn, David Charbonneau, David R. Ciardi, Karen A. Collins, John P. Doty, Etienne Bachelet, Daniel Harbeck
Summary: TO1-2285b is a sub-Neptune-sized planet orbiting a nearby M dwarf, with characteristics of radius, mass, and insolation flux. Despite being outside the habitable zone, the presence of liquid water is possible under certain conditions. The bright host star makes it an excellent target for further observations.
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
(2022)
Article
Geochemistry & Geophysics
T. Kodama, H. Genda, J. Leconte, A. Abe-Ouchi
Summary: This study systematically investigates the complete freezing limit for Earth-like exoplanets with different surface water distributions, finding that land planets have a higher greenhouse threshold and lower albedo compared to aqua planets. The results show the importance of water distribution in determining the onset of a global ice-covered state for terrestrial planets.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2021)
Article
Astronomy & Astrophysics
Mayuko Mori, John H. Livingston, Jerome de Leon, Norio Narita, Teruyuki Hirano, Akihiko Fukui, Karen A. Collins, Naho Fujita, Yasunori Hori, Hiroyuki Tako Ishikawa, Kiyoe Kawauchi, Keivan G. Stassun, Noriharu Watanabe, Steven Giacalone, Rebecca Gore, Ashley Schroeder, Courtney D. Dressing, Allyson Bieryla, Eric L. N. Jensen, Bob Massey, Avi Shporer, Masayuki Kuzuhara, David Charbonneau, David R. Ciardi, John P. Doty, Emma Esparza-Borges, Hiroki Harakawa, Klaus Hodapp, Masahiro Ikoma, Kai Ikuta, Keisuke Isogai, Jon M. Jenkins, Taiki Kagetani, Tadahiro Kimura, Takanori Kodama, Takayuki Kotani, Vigneshwaran Krishnamurthy, Tomoyuki Kudo, Seiya Kurita, Takashi Kurokawa, Nobuhiko Kusakabe, David W. Latham, Brian McLean, Felipe Murgas, Jun Nishikawa, Taku Nishiumi, Masashi Omiya, Hugh P. Osborn, Enric Palle, Hannu Parviainen, George R. Ricker, Sara Seager, Takuma Serizawa, Huan-Yu Teng, Yuka Terada, Joseph D. Twicken, Akitoshi Ueda, Roland Vanderspek, Sebastien Vievard, Joshua N. Winn, Yujie Zou, Motohide Tamura
Summary: This study presents the discovery and validation of a temperate sub-Neptune around a nearby mid-M dwarf star. The planet has a large radius ratio and a high transmission spectroscopy metric, making it an interesting candidate for atmospheric characterizations.
ASTRONOMICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Tadahiro Kimura, Masahiro Ikoma
Summary: According to a planetary population model, Earth-mass planets in the classical habitable zone of M dwarfs may have a wider range of water content than previously expected. This finding has significant implications for current and future M-dwarf planet survey missions.
Article
Astronomy & Astrophysics
Takanori Kodama, Daisuke Takasuka, Sam Sherriff-Tadano, Takeshi Kuroda, Tomoki Miyakawa, Ayako Abe-Ouchi, Masaki Satoh
Summary: Planetary climates are influenced by orbital parameters such as obliquity, eccentricity, and precession. High-obliquity exoplanets exhibit extreme seasonal cycles, and cloud-related processes play a significant role in shaping their climates, especially in high-resolution simulations.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Teruyuki Hirano, Fei Dai, John H. Livingston, Sascha Grziwa, Kristine W. F. Lam, Yui Kasagi, Norio Narita, Hiroyuki Tako Ishikawa, Kohei Miyakawa, Luisa M. Serrano, Yuji Matsumoto, Eiichiro Kokubo, Tadahiro Kimura, Masahiro Ikoma, Joshua N. Winn, John P. Wisniewski, Hiroki Harakawa, Huan-Yu Teng, William D. Cochran, Akihiko Fukui, Davide Gandolfi, Eike W. Guenther, Yasunori Hori, Kai Ikuta, Kiyoe Kawauchi, Emil Knudstrup, Judith Korth, Takayuki Kotani, Vigneshwaran Krishnamurthy, Tomoyuki Kudo, Takashi Kurokawa, Masayuki Kuzuhara, Rafael Luque, Mayuko Mori, Jun Nishikawa, Masashi Omiya, Jaume Orell-Miquel, Enric Palle, Carina M. Persson, Seth Redfield, Eugene Serabyn, Alexis M. S. Smith, Aoi Takahashi, Takuya Takarada, Akitoshi Ueda, Vincent Van Eylen, Sebastien Vievard, Motohide Tamura, Bun'ei Sato
Summary: We report the discovery of an Earth-sized transiting planet (R(p) = 1.015 +/- 0.051 R(circle plus)) in a 4.02-day orbit around K2-415 (EPIC 211414619), an M5V star at a distance of 22 parsecs. The planet candidate was initially identified using data from the K2 mission and has now been confirmed using the most recent data from TESS. Follow-up observations, including high-resolution imaging and near-infrared spectroscopy with IRD, ruled out false-positive scenarios, giving a low false-positive probability of 2 x 10(-4). Based on radial velocity measurements, the planet's mass is estimated to be 3.0 +/- 2.7 M(circle plus) for K2-415b, making it one of the lowest-mass stars (approximately 0.16 M(circle dot)) known to host an Earth-sized transiting planet. Further observations, such as additional radial velocity monitoring and transit spectroscopy, will be conducted to study K2-415b in more detail.
ASTRONOMICAL JOURNAL
(2023)
Proceedings Paper
Astronomy & Astrophysics
Shingo Kameda, Go Murakami, Alexander Tavrov, Keigo Enya, Mikhail Sachkov, Masahiro Ikoma, Norio Narita, Oleg Korablev
Summary: Many Earth-sized potentially habitable exoplanets have been discovered, and a UV spectrograph called UVSPEX has been designed to detect Earth-like atmospheres on these planets.
SPACE TELESCOPES AND INSTRUMENTATION 2020: ULTRAVIOLET TO GAMMA RAY
(2021)
Proceedings Paper
Astronomy & Astrophysics
Hajime Kawahara, Kento Masuda, Takayuki Kotani, Shotaro Tada, Hirokazu Kataza, Satoshi Ikari, Hiroki Aohama, Takayuki Hosonuma, Wataru Mikuriya, Masahiro Ikoma, Satoshi Kasahara, Shigeyuki Sako, Seiji Sugita, Eri Tatsumi, Kazuo Yoshioka
Summary: Researchers proposed using the LOTUS mission to monitor long-period transiting exoplanets, addressing current challenges in the field. LOTUS employs a specific design to ensure accurate monitoring of long-period planets near bright stars, and a conceptual design for the system was presented.
SPACE TELESCOPES AND INSTRUMENTATION 2020: OPTICAL, INFRARED, AND MILLIMETER WAVE
(2021)