[M-IS08] Astrobiology

[MIS08-02] Ultraviolet observation of terrestrial exoplanets using future space telescopes and beyond

★Invited Papers

*Shingo Kameda¹, Akifumi Nakayama¹, Masaki Kuwabara¹, Mao Kishida¹, Takanori Kodama², Go Murakami³, Masahiro Ikoma⁴, Naoki Terada⁶, Norio Narita⁵, Keigo Enya³ (1.School of Science, Rikkyo University, 2.Earth-Life Science Institute, Institute of Science Tokyo, 3.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 4.Division of Science, National Astronomical Observatory of Japan, 5.The University of Tokyo, 6.Graduate School of Science, Tohoku University)

Keywords:exoplanet, space telescope, planetary atmosphere

Many Earth-sized planets have already been discovered, and several Earth-like planets have been detected in the habitable zone of low-mass stars near the solar system. Transit spectroscopy is an effective method for observing atmospheres, but it requires extremely high precision to observe the thin lower atmospheres of small terrestrial planets, and at present no atmospheres of terrestrial exoplanets have been detected. On the other hand, low-mass stars have very strong XUV radiation even in the habitable zone, which may cause the upper atmospheres of terrestrial planets to extend to more distant regions with high density. In this study, we investigate the possibility of detecting the upper atmospheres of terrestrial exoplanets by transit spectroscopic observations with future ultraviolet space telescopes. There are several atomic and ionic emission lines (H, C, N, and O) in the far UV spectral range. Though we could not immediately conclude that the exoplanet has an ocean even if we detect H and O upper atmosphere, The results of the observations will provide important information for understanding the lower atmosphere and surface environment especially in case the lower atmosphere of the exoplanet cannot be detected.
In this presentation, we introduce the current status of our activity on UV observation using future UV space telescopes and the UV instrument technology development. In addition, we discuss a future plan on exoplanet observation and solar system exploration.