[P-EM11] Exoplanet

[PEM11-17] Life-environmentology, Astronomy, and PlanetarY Ultraviolet Telescope Assembly (LAPYUTA)

*Fuminori Tsuchiya¹, Go Murakami², Atsushi Yamazaki², Shingo Kameda³, Akifumi Nakayama³, Masahiro Ikoma⁴, Masaki Kuwabara³, Norio Narita⁵, Takanori Kodama⁵, Naoki Terada¹, Shin Toriumi², Yuta Notsu^10,11, Kosuke Namekata⁴, Tomoki Kimura⁶, Chihiro Tao⁷, Ryoichi Koga⁸, Jun Kimura⁹, Masami Ouchi^5,4, Masaomi Tanaka¹, Kei Masunaga², Shotaro Sakai¹, Kazuo Yoshioka⁵, Masato Kagitani¹, Keigo Enya² (1.Tohoku University, 2.ISAS/JAXA, 3.Rikkyo University, 4.NAOJ, 5.The University of Tokyo, 6.Tokyo University of Science, 7.NICT, 8.Nagoya University, 9.Osaka University, 10.Tokyo Institute of Tech., 11.Colorado University)

Keywords:Jupiter, Earth type planet, Exoplanet

Ultraviolet observation technique is one of the most powerful tools to cover wide science fields, from planetary science to astronomy. Here we propose a UV space telescope, LAPYUTA (Life-environmentology, Astronomy, and PlanetarY Ultraviolet Telescope Assembly), as a Japanese-leading mission, by using heritages of UV instruments for planetary science (e.g., Hisaki) and space telescope techniques for astronomy. We will accomplish the following four objectives. In Objectives 1 and 2, we focus on the boundary region between space and planets/moons which is a key exploration region to understand the habitable environment. In Objective 1, we make the first-ever continuous monitoring of the water plumes erupted at the surface of Jupiter's icy moons to obtain information of the subsurface ocean and transport of energy and mass from space to the icy moons to uncover form of liquid water and energy supply process in the icy moons. We also examine the global distribution of water and greenhouse gas transported from the lower to the upper atmosphere of Mars and Venus to uncover how these gases diffuse into space through the coupling between the lower and upper atmospheres, responding to the solar wind, the solar activities, and crustal magnetic fields. They will lead us to give insights into the habitable environment of Mars and Venus. In Objective 2, we will extend knowledges obtained for the solar system planet to exoplanets and utilize them to characterize exoplanet atmospheres and the surface environment. At the same time, we will explore the stellar activity that influences exoplanetary environments, like the Sun in our solar system. Behind the issue of habitable environments in the planetary system, there lie the fundamental interests how the universe itself evolved and how the structure of the universe was formed to its present form. The formation process of galaxies is one of the fundamental questions that remain in the history of structure formation in the universe. In Objective 3, we will examine whether structures of present-day galaxies ubiquitously include Lyα halos, and reveal the physical origins of Lyα halos from three major scenarios, cold accretion dubbed cold streams, satellite galaxies, and circum-galactic HI gas. In the material evolution of the universe, too, fundamental issues remain, one of which is the elucidation of the elemental synthesis process of heavy elements. In Objective 4, we aim to understand the entire picture of the heavy element nucleosynthesis by neutron star mergers, which leads to understand the origin of heavy elements in the Universe. Also, by observing the first signals from supernovae, we constrain the spectral energy distribution from the very early phase of stellar explosions, which leads to understand the final stage of massive star evolution.
To achieve these science objectives, LAPYUTA aims to carry out spectroscopy with a large effective area (>300 cm²) and a high spatial resolution (0.1 arc-sec) and imaging in far ultraviolet spectral range (110-190 nm) from a space telescope. The main part of the science payload is a Cassegrain-type telescope with a 60 cm-diameter primary mirror. Two main UV instruments are installed on the focal plane of the telescope: a spectrograph and a slit imager. The spectrograph will have a spectral resolution of 0.02 nm and field-of-view of 100 arc-sec. The UV slit imager consists of imaging optics, several bandpass filters with a rotation wheel, and a UV detector as the one installed in the spectrometer. To achieve a high spatial resolution of 0.1 arc-sec, a target monitoring camera at 0th order position inside the spectrometer and slit imager for both attitude control and image accumulation process will be installed.