宇宙科学談話会

ISAS Space Science Colloquium & Space Science Seminar

FY2018

ENGLISH

Searching for Planets like Earth around Late-M Dwarfs using Subaru/IRD

佐藤 文衛 特定准教授(Bunei SATO, Specific associate professor)
東京工業大学(Tokyo Institute of Technology)

We plan to conduct an extensive, precise near-infrared (NIR) RV survey focused on late-M dwarf stars (LMDs) using newly commissioned InfraRed Doppler (IRD) instrument and Subaru telescope. IRD is an echelle spectrometer that covers the wavelengths from 0.97 to 1.75 m with a high spectral resolution (70,000). IRD's high instrumental stability and its use of a laser frequency comb as a very precise wavelength reference allow us to measure the RVs of LMDs with a precision of 2 m/s or better.
The goals of our survey are: (1) to discover small rocky planets in the habitable zone around these low-mass stars, and (2) to uncover the distribution of planetary systems containing Earth-mass planets and more massive planets. We here outline our planet search project and also introduce other observations that will be possible using IRD.

Place: Shin-A 2F Conf. room A (1257) / 新A棟2階会議室A(1257号室)

ENGLISH

Space Colony Research Center at the Tokyo University of Science ーDeveloping technology for moon-base habitation and its application to the earth societyー

木村 真一 教授(Dr. Shinichi KIMURA),向井 千秋 特任副学長(Dr. Chiaki MUKAI)
東京理科大学(Tokyo University of Science)

Space exploration stimulates our imaginations and empowers our activities to make our dreams to happen. With hopes future living on the moon-base supported by science and technology, the Tokyo University of Science (TUS) established the Space Colony Research Center last year, funded by the Private University Research Branding Project of the Ministry of Education, Culture, Sports, Science and Technology (MEXT).
The center interdisciplinary works amongst in-house researchers as well as outside academia with the collaboration of government and industry.
The goal of the Center is to further improve technology in areas the TUS excels at, making the technology viable in space and creating a virtuous cycle of technological innovation on Earth as well. It is comprised of four teams: 1) The Space Agriculture Team, researching hydroponics to grow food in space; 2) The Energy Creation and Storage Technology Team, researching the generation of energy necessary to support life in space; 3) The Water and Air Recycling Technology Team, researching how to recycle these limited resources; and 4) The Space system development and Quality of Life Design Team, in charge overall and researching medical and other systems for while living in space. The core of their research is based around photocatalysis and high-efficiency energy generation with a low environmental impact, strengths of the university.
Our plan of the Space Colony Research Center will be discussed. And the concept of the moon-base frontier medicine to ensure safe and productive human activities will be briefly introduced.

Place: 2F Conf. room(1236) / 研究管理棟2階会議場(1236号室)

ENGLISH

Basilisk - Next Generation of Open Spacecraft Simulation and Mission Analysis Tool

Dr. Hanspeter Schaub
Univ. of Colorado Boulder

The Basilisk framework is an modular C/C++ based simulation environment that is wrapped with Python to make it scriptable. This allows for dynamics actuators, sensor, and space environment forces to me modeled in an interchangeable manner. This seminar highlights on- going Basilisk related research efforts between the Autonomous Vehicle Systems Lab and the Laboratory of Atmospheric and Space Physics, and how this is changing how mission simulations and autonomous software is being developed.

※通常と曜日が異なりますので、ご注意ください。

Place: 2F Conf. room(1236) / 研究管理棟2階会議場(1236号室)

日本語

超小型衛星打上げ機SS-520 5号機の実験結果について

羽生 宏人 准教授(Hiroto HABU, Associate professor)
ISAS/JAXA 宇宙飛翔工学研究系

2018年2月3日にSS-520 5号機を打上げ、超小型衛星TRICOM-1Rの軌道投入実験を行った。ロケットは計画通り飛行し、発射後7分30秒後にTRICOM-1Rを分離して、軌道投入実験は成功した。本研究開発活動は、2015年に採択された経済産業省の委託事業を基礎に所内プロジェクトとして設置された。2017年1月15日に最初の実験としてSS-520 4号機により実行したが、機体の不具合により超小型衛星TRICOM-1の軌道投入に失敗した。実験後の原因究明結果から、不具合の主たる推定原因は電源系のショートであることが判明した。SS-520 5号機実験は、必要な技術対策や改善を施して4号機再実験として実施された。今回は研究開発の技術的な観点のみならず、打上げ現場の実務の様子も合わせて紹介する。

Place: 2F Conf. room(1236) / 研究管理棟2階会議場(1236号室)

ENGLISH

Small Worlds - Big Discoveries

James Green, Chief Scientist
NASA

One of the most important sets of objects in our solar system are small bodies such as asteroids, planetesimals, protoplanets, dwarf planets, and comets. These small worlds provide a wealth of knowledge that, if properly understood, can tell us an enormous amount about the origin and evolution of the solar system. They represent remnants of the building blocks of the planets and provide insight into the conditions of our earliest history. It is also well known that after the formation of the solar system continual impacts by small bodies to the terrestrial planets were the delivery mechanism of key elements that perhaps gave rise to the origin of life here on Earth. Small bodies also experience a myriad of processes, providing numerous natural science laboratories to gain knowledge into the evolution of the solar system. In addition, small bodies represent both hazards, such as Near Earth Objects, but also potential future resources, as humans leave low Earth orbit and trek out into the solar system their need for future materials and fuels may largely be met by mining certain types of small bodies.

This talk will place the current small worlds missions, mostly by JAXA and NASA, into a broader context of the importance small bodies plays in the solar system and what they are telling us. This is truly an exciting time for exploring these small worlds allowing true missions of discovery. We have much to learn from them.

通常と曜日・時間が異なりますので、ご注意ください。

Place: 2F Conf. room(1236) / 研究管理棟2階会議場(1236号室)

ENGLISH

Astrochemical Approach to Star and Planet Formation

坂井南美 主任研究員(Nami SAKAI)
理化学研究所(RIKEN)

星の形成は宇宙における最も基本的な構造形成過程であるとともに、星間物質か ら惑星系物質への物質進化の場でもある。したがって、「太陽系のような環境がどれほど宇宙で普遍的に存在するのか?」この究極の問いに答えるためには、物理進化・化学進化の両面から研究展開することが重要である。本講演では、アルマ望遠鏡の観測結果をもとに、そのようなアプローチによる研究成果について紹介する。

Star and planet formation is one of the most fundamental structure-formation processes in the Universe. Physical processes of star and planet formation have widely been investigated as one of the major targets of astronomy and astrophysics by observations in the entire wavelength region during the last few decades. Although a rough outline of these processes has been presented, there still remain many unknowns and missing links. One of them is when the disk structure is formed around a protostar, and how it is evolved into a protoplanetary disk and eventually to a planetary system. At the same time, understanding the evolution of matter from interstellar clouds to stars and planets is also a goal of astronomy. So far, about 200 interstellar molecules have been identified mainly by radio-astronomical observations. This indicates the high chemical complexity of interstellar clouds even in the extreme condition of low temperature (10-100 K) and low density (102-107 cm-3), which would ultimately be related to an origin of rich substances in the Solar System. Thus, approaches both from physical and chemical view points are indispensable to bridge star/planet formation studies and planetary science of the Solar System. In this talk, I am going to present importance of chemistry in astronomical studies by introducing some observational results.

Place: 2F Conf. room(1236) / 研究管理棟2階会議場(1236号室)

ENGLISH

NASA's Neutron star Interior Composition Explorer (NICER) mission

榎戸 輝揚 特定准教授(Teruaki ENOTO, Specific associate professor)
京都大学理学研究科(Kyoto UNIVERSITY)

I will present an overview of the NASA's Neutron star Interior Composition Explorer (NICER) mission which was installed aboard the International Space Station in June 2017. NICER provides high-precision timing measurements of neutron stars, objects containing ultra-dense matter at the threshold of collapse into black holes.

※通常と曜日が異なりますので、ご注意ください。

Place: 2F Conf. room(1236) / 研究管理棟2階会議場(1236号室)

ENGLISH

重力波天体のマルチメッセンジャー観測
Multi-messenger observations of gravitational wave sources

田中雅臣 准教授(Masaomi TANAKA, Associate professor)
東北大学大学院 理学研究科 (TOHOKU UNIVERSITY)

史上初めて検出された中性子星合体からの重力波イベント(GW170817)は広い波長域の電磁波でも観測され、本格的なマルチメッセンジャー天文学が幕を開けました。談話会では、重力波天体のマルチメッセンジャー観測を概観し、理解が進みつつある宇宙の重元素の起源についてお話しします。

On 17th August 2017, the first gravitational wave (GW) detection from a neutron star merger (GW170817) was achieved. The detection triggered electromagnetic (EM) wave observations over the entire wavelength range, which marked the beginning of a new era of "multi-messenger" astronomy. In this seminar, I briefly review multi-messenger observations of GW170817 and show results of optical and near-infrared observations of the EM counterpart. The observed properties of optical and near-infrared emission are similar to those of theoretically-expected "kilonova", which is powered by radioactive decays of r-process nuclei. I discuss implications for the origin of heavy elements in the Universe.

Place: 2F Conf. room(1236) / 研究管理棟2階会議場(1236号室)

ENGLISH

ESA Planck Mission

Jan Tauber, Project Scientist
ESA

This talk will present an overview of the Planck mission, including a brief outline of its development and of some of the challenges that it presented. I will then review the most recent Planck data and results, with emphasis on polarization. The use of CMB polarization data from Planck confirms the best-fit Lambda-CDM model obtained with Planck temperature-only data, and improves the accuracy with which cosmological parameters are determined. The most recent results based on polarized E- mode and B-mode CMB power spectra at large angular scales have significant implications on our understanding of the epoch of reionization and primordial gravitational waves. If there is time, I will also present some of the latest analysis of polarized diffuse galactic foreground emissions based on Planck data. Both the synchrotron and dust emission maps obtained from Planck reveal new facets of the galactic interstellar medium.

Place: 2F Conf. room(1236) / 研究管理棟2階会議場(1236号室)

日本語

「ひさき」が明らかにした木星圏物理学とJUICEへの展望

木村 智樹 助教
東北大学

世界初の惑星専用宇宙望遠鏡である「ひさき」がトリガした国際連携に焦点を当 て、木星圏物理学の研究成果を紹介する。また、これらの成果から得られた知見 や経験に基づき、木星氷衛星探査JUICEが担うべき科学の将来展望についても議論 する。

Place: Shin-A 2F Conf. room A (1257) / 新A棟2階会議室A(1257号室)

ENGLISH

Chandra X-Ray Kinematics Study of Young Supernova Remnants

Prof. Sangwook Park
University of Texas at Arlington

Supernova remnants are an excellent laboratory to study fundamental subjects of modern astronomy and astrophysics such as stellar evolution and explosion. Realizing the 3-dimensional structure of supernova explosions is critical to understand the explosion physics and the nature of the exploded star. Based on the high resolution grating spectroscopy of Chandra X-ray Observatory, we can perform X-ray kinematic studies of metal-rich stellar debris of supernova explosions to address their 3-D nature. We briefly discuss such kinematic studies of supernova remnants, including our on-going studies of historical events: stellar explosions eye-witnessed in 1987, 1604, and 1572.

Place: 2F Conf. room(1236) / 研究管理棟2階会議場(1236号室)

ENGLISH

Precise and fast computation of gravitational field of general finite body and its application to gravitational study of small asteroids, small satellites, and comets

福島 登志夫 教授(Toshio Fukushima, Professor)
国立天文台(NAOJ)

In order to obtain the gravitational field of a general finite body inside its Brillouin sphere, we developed a new method to compute the field accurately. First, the body is assumed to consist of some layers in a certain spherical polar coordinate system and the volume mass density of each layer is expanded as a Maclaurin series of the radial coordinate. Second, the line integral with respect to the radial coordinate is analytically evaluated in a closed form. Third, the resulting surface integrals are numerically integrated by the split quadrature method using the double exponential rule. Finally, the associated gravitational acceleration vector is obtained by numerically differentiating the numerically integrated potential. Numerical experiments confirmed that the new method is capable of computing the gravitational field independently of the location of the evaluation point, namely whether inside, on the surface of, or outside the body. Also, it can provide sufficiently precise field values, say of 14--15 digits for the potential and of 9--10 digits for the acceleration, respectively. Furthermore, its computational efficiency is better than that of the polyhedron approximation. This is because the computational error of the new method decreases much faster than that of the polyhedron models when the number of required transcendental function calls increases.
As an application, we obtained the gravitational field of 433 Eros from its shape model expressed as the 24x24 spherical harmonic expansion by assuming the homogeneity of the object. The developed formulation would be easily applied to the Ryugu once its surface function is roughly estimated and/or precisely determined.
参考文献:
T. Fukushima 2017, Astron. J., 154:145

エロスやイトカワのような任意形状の天体の重力場を計算する新しい方法を開発した。計算精度と計算速度の両面で、従来の多面体(polyhedron)モデルを上回るばかりでなく、非一様な密度分布の場合にも適用可能である。

Place: Shin-A 2F Conf. room A(1257) / 新A棟2階会議室A(1257号室)