Article
Astronomy & Astrophysics
Kentaro Hattori, Hisashi Hayakawa, Yusuke Ebihara
Summary: This study analyzed a solar activity event in October 1788 that caused auroral observations in Europe and Japan. Multiple ICMEs arrived during a long storm sequence, enhancing solar activity at that time.
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
(2021)
Article
Astronomy & Astrophysics
T. Cavalie, B. Benmahi, V. Hue, R. Moreno, E. Lellouch, T. Fouchet, P. Hartogh, L. Rezac, T. K. Greathouse, G. R. Gladstone, J. A. Sinclair, M. Dobrijevic, F. Billebaud, C. Jarchow
Summary: In this study, wind speeds in Jupiter's stratosphere were measured to bridge the altitude gap between the tropospheric and ionospheric wind patterns. Zonal jets were detected at low-to-mid latitudes, while nonzonal winds were found at polar latitudes, potentially aiding in chemical complexification processes.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
A. D. Wibisono, G. Branduardi-Raymont, W. R. Dunn, T. Kimura, A. J. Coates, D. Grodent, Z. H. Yao, H. Kita, P. Rodriguez, G. R. Gladstone, B. Bonfond, R. P. Haythornthwaite
Summary: Results from multiwavelength observations of Jupiter's northern aurorae suggest a possible connection between magnetic reconnection, plasma injections, and electron precipitation in the auroral processes.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
O. Carrion-Gonzalez, A. Garcia Munoz, N. C. Santos, J. Cabrera, Sz Csizmadia, H. Rauer
Summary: This study investigates the subset of exoplanets suitable for reflected starlight measurements using the Roman Space Telescope coronagraph, finding that in an optimistic scenario, 26 exoplanets are detectable, with the population biased towards more massive planets. The intermediate and pessimistic scenarios yield lower numbers of detectable exoplanets, highlighting the importance of inclination estimates for refining detectability prospects.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Mayank Narang, Apurva Oza, Kaustubh Hakim, P. Manoj, Himanshu Tyagi, Bihan Banerjee, Arun Surya, Prasanta K. Nayak, Ravinder K. Banyal, Daniel P. Thorngren
Summary: In this study, the first radio observations of the exomoon candidate system WASP-69b were conducted. Although no radio emission was detected, upper limits were established and used to estimate the maximum mass-loss from the exomoon candidate.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
N. Erkaev, C. Weber, J-M Griessmeier, H. Lammer, V. A. Ivanov, P. Odert
Summary: We investigate the conditions of the atmosphere and magnetosphere of the massive and close-in exoplanet upsilon Andromedae b (ups And b). We explore the possibility of radio emission produced by the Cyclotron Maser Instability (CMI) and whether it can escape its source region. The comparison between the local cyclotron frequency and the local plasma frequency depends on the planetary mass. The study determines at which mass the atmosphere becomes 'compact' and provides favorable conditions for the CMI.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Oscar Carrion-Gonzalez, Jens Kammerer, Daniel Angerhausen, Felix Dannert, Antonio Garcia Munoz, Sascha P. Quanz, Olivier Absil, Charles A. Beichman, Julien H. Girard, Bertrand Mennesson, Michael R. Meyer, Karl R. Stapelfeldt, LIFE Collaboration
Summary: In this study, the authors use a statistical methodology to process the NASA Exoplanet Archive and compute orbital realizations for known exoplanets. They find that the mid-infrared Large Interferometer For Exoplanets (LIFE) and the future Habitable Worlds Observatory (HWO) have the capability to detect and characterize a large number of exoplanets. Specifically, LIFE can detect 212 known exoplanets, 49 of which are also accessible to HWO in reflected starlight. This study highlights the potential for groundbreaking analyses of low-mass, habitable-zone exoplanets.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Jake D. Turner, Philippe Zarka, Jean-Mathias Griessmeier, Joseph Lazio, Baptiste Cecconi, J. Emilio Enriquez, Julien N. Girard, Ray Jayawardhana, Laurent Lamy, Jonathan D. Nichols, Imke de Pater
Summary: The research presents observations of exoplanetary radio emissions using LOFAR low-frequency antennas targeting the systems of 55 Cancri, upsilon Andromedae, and tau Bootis. The study developed the BOREALIS pipeline to mitigate radio frequency interference and tentatively detected bursty and slowly variable radio emissions from the tau Bootis system. Further observations are needed to confirm these potential first detections of exoplanetary radio signals.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
S. R. N. McIntyre
Summary: This study explores the role of the long-term carbon cycle on tidally locked rocky exoplanets in maintaining surface liquid water and supporting habitability. By calculating tidal stress and tidal heating rates, the study finds that about 10% of the exoplanets can sustain mobile lid tectonic activity, similar to plate tectonics on Earth, and retain surface liquid water. However, about 40% of the exoplanets in the sample would be unable to maintain the necessary tectonic activity. Furthermore, the study identifies optimal regions for future observations, with tidally driven tectonic activity predominantly occurring around M dwarfs.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
S. Fonte, D. Turrini, E. Pacetti, E. Schisano, S. Molinari, D. Polychroni, R. Politi, Q. Changeat
Summary: In this study, we investigate the influence of temperature and non-solar abundances of oxygen and refractory elements on the atmospheric C/O ratio of high-metallicity giant exoplanets. Our results show that the interaction between atmospheric temperature and the abundances of oxygen and refractory elements can significantly affect the C/O ratio estimation. Applying our findings to Jupiter in the Solar System, we find that the currently estimated water abundance indicates an oxygen abundance four times that of the Sun's.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Hisashi Hayakawa, Tomoya Iju, Shoma Uneme, Bruno P. Besser, Shunsuke Kosaka, Shinsuke Imada
Summary: The solar activity during the Maunder Minimum was significantly different from modern observations in terms of sunspot group number and positions. Researchers studied the original records of Martin Fogelius and Heinrich Siverus to revise their data and correct potential underestimations of solar cycle amplitudes during the Maunder Minimum. The study also compared the positions of notable sunspot groups recorded during the Maunder Minimum, indicating a long lifespan for these active regions.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Liang Xiang, Bing Ma, Qiu-Huan Li, Ling Chen, Hong-Wei Yu, De-Jin Wu
Summary: Based on in-situ observations and two-fluid theory, the dispersion relation and polarization properties of fast, Alfven, and slow modes in the presence of a displacement current were investigated. Results show that fast and Alfven modes are highly sensitive to the normalized Alfven velocity, plasma beta, and propagation angle, while the slow mode shows minor dependence. The presence of displacement current leads to significant changes in magnetic helicity and compressibility for the waves.
RESEARCH IN ASTRONOMY AND ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
N. Erkaev, M. Scherf, S. E. Thaller, H. Lammer, A. Mezentsev, V. A. Ivanov, K. E. Mandt
Summary: The study suggests that significant thermal escape of nitrogen on Titan likely occurred very early in its history with high solar extreme ultraviolet fluxes, impacting its atmospheric mass significantly. The origin of Titan's nitrogen, partially through NH3-ices, might be influenced by the Sun's rotational evolution, with implications for the survival of the atmosphere and potential nitrogen sources.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Ruonan Chen, Yi Xu, Minggang Xie, Ling Zhang, Shengli Niu, Roberto Bugiolacchi
Summary: This study used a modified method to estimate the fine-resolution spatial distribution of relative permittivity and improve the interpretation of the geological processes in the landing area of China's Chang'E-4 probe. The results show sub-surface stratification, determined the depth of prominent sub-surface interfaces, and obtained the thickness and permittivity values of regolith and rock debris. The permittivity map is consistent with the radargram and reveals detailed variations of material properties both inside and outside craters.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Zhen Li, Lijun Chang, Jiahui Lou, Yi Shen, Haoming Yan
Summary: This study investigates the relationship between total solar irradiance (TSI) and global surface temperature (GST) using wavelet coherence, and finds that TSI has a significant impact on GST with a delay effect at the characteristic scale of 22 years. However, this relationship has been perturbed by excessive CO2 emissions.
RESEARCH IN ASTRONOMY AND ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Harufumi Tamazawa, Akito Davis Kawamura, Hisashi Hayakawa, Asuka Tsukamoto, Hiroaki Isobe, Yusuke Ebihara
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
(2017)
Article
Astronomy & Astrophysics
Hisashi Hayakawa, Yasuyuki Mitsuma, Yasunori Fujiwara, Akito Davis Kawamura, Ryuho Kataoka, Yusuke Ebihara, Shunsuke Kosaka, Kiyomi Iwahashi, Harufumi Tamazawa, Hiroaki Isobe
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
(2017)
Article
Astronomy & Astrophysics
Ryuho Kataoka, Hiroaki Isobe, Hisashi Hayakawa, Harufumi Tamazawa, Akito Davis Kawamura, Hiroko Miyahara, Kiyomi Iwahashi, Kazuaki Yamamoto, Masako Takei, Tsuneyo Terashima, Hidehiko Suzuki, Yasunori Fujiwara, Takuji Nakamura
SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS
(2017)
Article
Astronomy & Astrophysics
Hisashi Hayakawa, Yusuke Ebihara, Jose M. Vaquero, Kentaro Hattori, Victor M. S. Carrasco, Maria de la Cruz Gallego, Satoshi Hayakawa, Yoshikazu Watanabe, Kiyomi Iwahashi, Harufumi Tamazawa, Akito D. Kawamura, Hiroaki Isobe
ASTRONOMY & ASTROPHYSICS
(2018)
Article
Astronomy & Astrophysics
Hisashi Hayakawa, Kiyomi Iwahashi, Masashi Fujiyama, Toshiki Kawai, Shin Toriumi, Hideyuki Hotta, Haruhisa Iijima, Shinsuke Imada, Harufumi Tamazawa, Kazunari Shibata
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
(2018)
Article
Astronomy & Astrophysics
Hisashi Hayakawa, Kiyomi Iwahashi, Harufumi Tamazawa, Shin Toriumi, Kazunari Shibata
Article
Astronomy & Astrophysics
Hisashi Hayakawa, Yusuke Ebihara, Jose M. Vaquero, Kentaro Hattori, Victor M. S. Carrasco, Maria de la Cruz Gallego, Satoshi Hayakawa, Yoshikazu Watanabe, Kiyomi Iwahashi, Harufumi Tamazawa, Akito D. Kawamura, Hiroaki Isobe
ASTRONOMY & ASTROPHYSICS
(2018)
Article
Astronomy & Astrophysics
Daikichi Seki, Kenichi Otsuji, Hiroaki Isobe, Takako T. Ishii, Kiyoshi Ichimoto, Kazunari Shibata
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
(2019)
Article
Astronomy & Astrophysics
Daikichi Seki, Kenichi Otsuji, Hiroaki Isobe, Giulio Del Zanna, Takako T. Ishii, Takahito Sakaue, Kiyoshi Ichimoto, Kazunari Shibata
Summary: The passage discusses the eruption of a filament in the solar corona, noting an increase in microturbulence and coronal line emission prior to the event. It suggests that studying turbulent motions in a filament could serve as a useful precursor for predicting filament eruptions in space weather forecasting.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Durgesh Tripathi, V. N. Nived, Hiroaki Isobe, G. Gerard Doyle
ASTROPHYSICAL JOURNAL
(2020)
Article
Astronomy & Astrophysics
Hiroaki Isobe, Yusuke Ebihara, Akito D. Kawamura, Harufumi Tamazawa, Hisashi Hayakawa
ASTROPHYSICAL JOURNAL
(2019)
Article
Astronomy & Astrophysics
K. A. P. Singh, Takahito Sakaue, Naoki Nakamura, Akito D. Kawamura, Hiroaki Isobe, Kazunari Shibata
ASTROPHYSICAL JOURNAL
(2019)