宇宙科学談話会

ISAS Space Science Colloquium & Space Science Seminar

FY2021

ENGLISH

ハビタブル系外惑星探査のための高コントラスト撮像技術の開発

Naoshi Murakami(村上 尚史)
北海道大学

It is challenging to directly image exoplanets, especially Earth-like planets in habitable zones, due to a huge brightness ratio between bright central star and faint exoplanet. The ratio would reach 1E+10 assuming, for example, a search for our Earth around the Sun by aliens from outside the solar system. It is necessary to develop high-contrast imaging technology for strongly rejecting bright starlight to directly image exoplanets. Recently, we have constructed two laboratory testbeds named "FACET" and "EXIST" where novel optical devices and methodology are being developed toward future space-based coronagraphs to search for habitable exoplanets. In my talk, I will describe difficulties for direct imaging of habitable exoplanets, summarize key techniques for the high-contrast imaging envisioned for future coronagraphs, and introduce our recent activities carried out at the testbeds FACET and EXIST.

Via Zoom / zoom 開催

ENGLISH

Giant planet astronomy in the Solar System and beyond

James Odonoghue
ISAS/JAXA 太陽系科学研究系

Giant planet astronomy in the Solar System and beyond" In this talk I will give an update on my work using ground-based telescopes to study the upper atmospheres of Jupiter, Saturn and an exoplanet. At Jupiter we are exploring a planetary-scale hot feature which seems to be leaving the auroral region -- we plan to make a paper which talks all about it in FY2021/22. At Saturn I will report that we have not been able to detect H3O+, a type of water molecule, in Saturn's upper atmosphere, but detail some new ways we might be able to detect it using the SOFIA telescope (a telescope which is on a plane, run by NASA). We have an upcoming exoplanet observation in April which I will also discuss. Finally, I was offered the chance to write a review paper on the remote sensing of Jupiter, Saturn, Uranus and Neptune upper atmospheres, so I will discuss that as well.

Via Zoom / zoom 開催

ENGLISH

From the Sun to the Stars: Theoretical and Observational Approaches to Understand Solar/Stellar Activities

Shin Toriumi(鳥海 森)
ISAS/JAXA 太陽系科学研究系

The Sun and stars have common magnetic activity phenomena, as represented by flares and coronal mass ejections that occur in highly magnetized active regions. This year (the third year as an ITYF), I conducted research to investigate the universality of atmospheric heating in the Sun and solar-like stars. The central issue is whether the same atmospheric heating mechanism occurs in other stars with different activities from the Sun. To this end, we systematically surveyed the response of the solar atmospheres to the surface magnetic flux over a wide range of temperatures. Analyzing 10 years of multi-wavelength synoptic observations of the Sun reveals the power-law proportionalities between irradiances and magnetic flux, in which the power-law exponent decreases from above- to sub-unity as the temperature drops from the corona to the chromosphere. In addition, this tendency showing the efficiency of atmospheric heating can be extended to sun-like stars. This study provides observational evidence that the mechanism of atmospheric heating is universal between the Sun and stars, regardless of age or activity. In the ITYF seminar, I will report on the research activity in FY2021 with mainly focusing on the above study.

Via Zoom / zoom 開催

ENGLISH

Novel Robotic Solutions for Space Exploration and Colonization

Stephane Bonardi
ISAS/JAXA 宇宙機応用工学研究系

In this talk, I will present the progress made and the future prospects in creating disruptive robotic concepts to tackle the upcoming challenges of ambitious space missions.

Via Zoom / zoom 開催

ENGLISH

Theoretical studies of planet formation towards planetary explorations

Ryuki Hyodo(兵頭 龍樹)
ISAS/JAXA 太陽系科学研究系

In this talk, I will explain three theoretical studies of planet formation oriented towards planetary explorations. First, studies of the origin and evolution of Martian moons, which became today's base of MMX's mission pillars, are reported. Secondly, studies of planetesimal formation, which has changed the classical view of planet formation and would become a new scientific objective of small body exploration, are presented. Lastly, the importance of exploring Saturn and its rings, which may be JAXA's future mission, is discussed.

Via Zoom / zoom 開催

ENGLISH

Revisiting and Resolving Dusty Massive stars in the Infrared

Lau Ryan Masami
ISAS/JAXA 宇宙物理学研究系

Driven by our revised understanding on the influence of binary companions in massive star evolution, my research has focused on revisiting the impact of carbon-rich Wolf-Rayet (WC) binaries as early and dominant sources of dust. Although these systems can produce copious amounts of dust, they have been commonly overlooked as significant sources of dust in the ISM of galaxies in the local and early Universe due to the persisting mysteries on their dust formation and the influence of binary companions. In pursuit of this research, I am leading an Early Release Science (ERS) program with the recently launched James Webb Space Telescope (JWST). In this talk, I will present my research program using ground- and space-based infrared (IR) observations to revisit and resolve dusty massive stars.

Via Zoom / zoom 開催

ENGLISH

Robotic Autonomy for Subterranean Exploration

Kyohei Otsu(大津恭平)
NASAジェット推進研究所

Subterranean voids are one of the most promising places to find the sign of life beyond Earth, as well as being the major candidates for future human colonization. This talk will present the robotic technology to allow autonomous exploration of subsurface environments, including navigation, mapping, networking, and science discovery.

Via Zoom / zoom 開催

日本語

3.6m分割望遠鏡による静止光学観測用イメージャの検討

水谷 忠均(Tadahito Mizutani)
宇宙航空研究開発機構 研究開発部門

災害等の緊急を要する状況において、衛星画像はそのレイテンシ(観測要求からデータ配信までの時間)の限界から活用範囲は限定的なものになる。提案する静止観測衛星では、このレイテンシ、すなわち時間分解能を最小化することを技術面の特長としている。一方で、静止軌道からの地球観測で実用的に十分な空間分解能を得るためには大型の望遠鏡が必要であり、技術の飛躍が必要となる。具体的には口径3.6mの光学望遠鏡を含む光学センサの技術成立性を検討中である。JAXA研究開発部門では、地上の大型望遠鏡開発で主流となっており、また、今年打ち上げが予定されているNASAのJames Webb Space Telescopeでも採用されている主鏡分割方式に注目し、宇宙機搭載の分割望遠鏡に必要となる技術について研究開発を進めている。

Via Zoom / zoom 開催

ENGLISH

Recent results with Fermi-LAT gamma-ray space telescope

Yasushi Fukazawa(深沢 泰司)、Tsunefumi Mizuno(水野 恒史)
広島大学

Fermi-LAT gamma-ray space telescope continues to observe GeV gamma-ray sky with all-sky survey mode since 2008. No significant hardware failures have occurred. Japanese members have took part in the Fermi-LAT team for data monitoring and science output. We here report recent results obtained with Fermi-LAT gamma-ray space telescope. We focus on the results where Japanese members have contributed much; multi-messenger astronomy, blazar and radio galaxies, supernova remnants and cosmic-rays, dark matter search, and so on.

Via Zoom / zoom 開催

ENGLISH

Development of gravitational wave detectors

Kiwamu Izumi(和泉 究)
International Top Young Fellow (ITYF)

The first direct observation of gravitational waves was achieved in 2015 by the ground-based gravitational wave detectors, opening up the new astronomy branch called gravitational wave astronomy. Since then, multiple gravitational wave events were observed including the binary neutron star mergers and black hole-neutron star mergers. Besides, there has been worldwide effort to put gravitational wave detectors in space, such as LISA, to further exploit the capability of gravitational wave astronomy. I have been involved with the development of both ground-based and space-borne gravitational wave detectors, namely LIGO, KAGRA and LISA.
In this talk, I will give an overview of where we stand in gravitational wave astronomy and present the status updates on the development of some of the gravitational wave detectors. In addition, I would like to introduce our recent laboratory activities for space-borne detectors beyond LISA.

Via Zoom / zoom 開催