2016.8.29-9.4

8月29日（月）13：30～14：30　　太陽系科学セミナー　　 中央棟（北）1F講義室
Aug 29 mon　　　　　　　　　　 Solar System Science Seminar Lecture Room 　　

8月29日（月）16：00～17：00　　国立天文台談話会 大セミナー室
Aug 29 mon　　　 NAOJ Seminar　　　　　 　　　　 Large Seminar Room

8月31日（水）13：30～14：30　　理論コロキウム 　 大セミナー室
Aug 31 wed　　　 DTA colloquium Large Seminar Room

9月1日（木） 10：30～12：00　 太陽天体プラズマセミナー 院生セミナー室
Sep 1 thu　 Solar and Space Plasma Seminar　 Student Seminar Room, Subaru Bldg.

9月1日（木） 15：00～16：00　 VLBIコロキウム 　　　　　中央棟(南)2階VLBIセミナー室
Sep 1 thu　 VLBI Colloquium　　　 　　　 　VLBI Seminar Room, Main Bldg. (South) 2F

9月2日（金） 16：15～17：30　 国立天文台談話会 大セミナー室
Sep 2 thu　 NAOJ Seminar　　　　　 　　　　 Large Seminar Room

詳細は以下をご覧下さい。

8月29日（月）

キャンパス

三鷹

セミナー名

太陽系科学セミナー

定例・臨時の別

定例

日時

8月29日（月）13:30-14:30

場所

講義室

講演者

山田竜平

所属

RISE

タイトル

Approachミッションによる月の科学

Abstract

これまで、月の内部構造についてはNASAのApolloミッションでの地震探査や、かぐや、GRAILでの重力場探査により、多くの情報が得られてきた。その一方で、月の地殻構造や深部構造など、未だ不確定な部分も多く、月の熱進化や起源に関して、十分な制約を与えられてはいない。
Approachミッションでは、過去のLUNAR-Aミッションで開発されたペネトレータをイプシロンロケットに搭載した小型衛星で打ち上げ、月面で地震観測と熱流量観測を行い、特に月の地殻構造と地殻内の難揮発性元素の存在量について新たな制約を与える事を目指している。

本講演では、Approachミッションでどのような科学観測を行い、どのような科学成果が得られるかについての詳細を発表する。また、本ミッションはJAXAの小型科学衛星の公募に対して、応募を行った経緯を持つ。この選考過程を通して得られた意見を基に、将来のペネトレータミッション、及び月内部構造探査ミッションの改良点と方向性について議論したい。

連絡先

-名前：脇田茂

-名前：松本晃治

-名前：土屋智恵

備考

テレビ会議またはスカイプによる参加も可

8月29日（月）

キャンパス

三鷹

セミナー名

国立天文台談話会

定例・臨時の別

臨時

日時

8月29日（月）　16:00-17:00

場所

大セミナー室

講演者

Tristan Guillot

所属

Observatoire de la Cote d’Azur

タイトル

Probing Jupiter’s interior: From gravimetry to seismology

Abstract

Jupiter is by far the most massive planet in our Solar System, yet its interior is still poorly known: We know that of the 318 Earth masses of the planet, most of it is hydrogen and helium, but the mass of the other elements (heavy elements) varies between 10 and 40 Earth masses depending on the model. We do not know whether it holds a dense central of up to 20 Earth masses or none at all.
These are very significant uncertainties preventing building detailed robust models of the formation of the Solar System. The JUNO spacecraft has arrived at Jupiter and will map the planet’s gravity and magnetic fields with unsurpassed accuracy. It will also attempt to constrain the deep abundance of water in the planet. These will be crucial pieces of information to better constrain the planet’s interior. However, these constraints will remain model-dependent. In parallel, another approach, probing Jupiter through seismology, is complementary and potentially extremely powerful. Among other things, it provides contraints on the sound speed inside the planet and is extremely sensitive to the presence of discontinuities in the interior. Jupiter’s oscillations have been detected by Gaulme et al. (2011) but require confirmation. Saturn has been proven to oscillate through the observation of its rings by the Cassini spacecraft (Hedman & Nicholson 2013). I will present JOVIAL, a project to observe Jupiter’s oscillations from three sites, in New Mexico (combined with JIVE), France and Japan. JOVIAL should greatly improve our understanding of the structure of the giant planets and of its atmospheric dynamics thanks to nearly-continuous observations of the planet using Doppler imaging in the visible.

連絡先

-名前： 滝脇　知也

8月31日（水）

Campus

Mitaka

Seminar

DTA colloquium

Regularly Scheduled/Sporadic

Regularly Scheduled Date and time：31 August 2016, 13:30-14:30

Place

Large Seminar Room, Subaru Building

Speaker

Sherry Suyu

Affiliation

MPA

Title

Shedding Light on the Dark Cosmos through Gravitational Lensing

Abstract

Gravitational lensing provides powerful means to study dark energy and dark matter in the Universe. In particular, strong lens systems with measured time delays between the multiple images can be used to determine the “time-delay distance” to the lens, which is primarily sensitive to the Hubble constant. Measuring the Hubble constant is crucial for inferring properties of dark energy, spatial curvature of the Universe and neutrino physics. I will describe the ingredients and newly developed techniques for measuring accurately time-delay distances with a realistic account of systematic uncertainties. A program initiated to measure the Hubble constant to <3.5% in precision from gravitational lens time delays is in progress, and I will present the latest results and their implications. Current and upcoming imaging surveys will contain thousands of new time-delay lenses, and I will describe ongoing efforts to find these objects. An exciting discovery is the first strongly lensed supernova, which has offered a rare opportunity to perform a true blind test of model predictions. I will describe the bright prospects of using gravitational lens time delays as an independent and competitive cosmological probe.

Facilitator

-Name：Tomoya Takiwaki

Comment

in English

9月1日（木）

Campus

Mitaka

Seminar

Solar and Space Plasma Seminar

Regularly Scheduled/Sporadic

Regular

Date and time

1 September (Thu), 10:30-12:00

Place

Student Seminar Room, Subaru Bldg.

Speaker

Yoshiaki Kato

Affiliation

ITA, University of Oslo

Title

New Insights into Chromospheric Structure and Dynamics ~ Oscillations and Vortices

Abstract

The chromosphere is known as a complicated structured layer in the outer solar atmosphere. The thermodynamic state of the chromosphere is strongly affected by the ionisation of hydrogen and helium, radiative cooling by strong lines from hydrogen, calcium, and magnesium, and by radiative heating by the UV irradiation from the corona. All of these effects should be taken into consideration so that one can investigate how the chromosphere is heated and why it creates a peculiar structure with high variability in time. Oscillations and vortices have come to my attention over the past few years, because they are observational signatures of waves that may play a vital role in sustaining the chromosphere as well as the corona.
Based on two-dimensional radiation magnetohydrodynamic (RMHD) simulations including the aforementioned physics, we have found that a process called magnetic pumping, induced by convective downdrafts in the upper convective layer, excites recursively magneto-acoustic shock waves, which propagate along magnetic flux concentrations, and compressive waves which propagate further into the corona. The heat flux resulting from these shocks is sufficient to compensate for the empirically determined radiative losses in the chromosphere, or for the estimated energy flux of observed magneto-acoustic waves in the upper photosphere. The magnetic pumping process is therefore relevant for chromospheric structure and dynamics (Kato et al. 2016).
The next step is elucidate the nature of chromospheric vortex flows, which are the observational signatures of magnetic tornadoes. As a first step, I have developed two automatic detection methods and tested them by using a model produced with three-dimensional RMHD simulations. We have found that a large number of vortices with smaller sizes and shorter life times than those found before. I will discuss a plausible application of our detection methods and address the importance of the combination of high-spatial/temporal resolution for future solar physics missions, because it is essential for understanding the structure and dynamics of so far unresolved vortices, which may contribute to chromospheric and coronal heating.

Facilitator

-Name：Shin Toriumi

9月1日（木）

キャンパス

三鷹

セミナー名

VLBIコロキウム

定例・臨時の別

定例

日時

9月1日（木）15:00-16:00

場所

中央棟(南)2階VLBIセミナー室

講演者

Tomoya Hirota

所属

Mizusawa VLBI Observatory

タイトル

High resolution ALMA cycle 2 observations of Orion Source I

Abstract

Orion Source I is thought to be the nearest high-mass protostar candidate at the distance of 418 pc. To investigate dynamical properties of a circumstellar disk/outflow system associated with Source I, we have been carrying out high resolution observations by using VLBI and ALMA. Here we present the latest results from ALMA cycle 2 observations of H2O and SiO lines at bands 8 at a resolution of 0.1″ (40 au). We successfully resolve the structure of the continuum emission from the edge-on disk. In addition, we detect more than 10 H2O, SiO, and their isotopologues including those at vibrationally excited state. The lower excitation H2O and SiO lines trace the northeast-southwest bipolar outflow with the scale of 200 AU while the higher excitation lines are mostly emitted from a compact structure smaller than <100 AU. They show clear rotation signatures around the outflow axis. We will discuss physical and dynamical properties of the disk/outflow system associated with Source I.

連絡先

-名前：倉持一輝

備考

英語、テレビ参加可

9月2日（金）

キャンパス

三鷹

セミナー名

国立天文台談話会

定例・臨時の別

臨時

日時

9月2日（金）　16:15-17:30

場所

大セミナー室

講演者1

Lars Lindberg Christensen

所属

The European Southern Observatory

タイトル

Benefits and challenges of a international big science organisation

Abstract

Science can play a role in societal change. The European Southern Observatory (ESO) as well as other big national and international organisations stand as proof that science can achieve exactly that. If we want to revolutionise the world we live in, then we need to continue doing breakthrough science. Some of those breakthroughs are made by clever boffins tinkering in the lab, or by small groups with a smart idea and a modest telescope. Others, though, require nations to work together, because no one nation has the wealth or the expertise to tackle the really big questions.

ESO has included the idea of collaboration across European borders in its mission from the very beginning. The vision of our founders is as valid today as it was 50 years ago: ESO designs, builds and operates the most powerful and complex ground-based telescopes in the world. Only a small fraction of what we do could be achieved by an individual nation. Only together can we make the fundamental advances. But such an undertaking involves working in multicultural teams with language barriers, and different cultures.

講演者2

Ian.Corbett

所属

Past General Secretary of Executive Committee (2009-2012)

タイトル

The Growth of International Collaboration

Abstract

Individual scientists have always collaborated but international collaboration at the government or national institution level is a development which grew rapidly in the latter part of the twentieth century. I will give a personal perspective on how this grew from projects involving a small number of nations working together to the large collaborations which have become the norm in much of modern scientific research.

連絡先

-名前： 滝脇　知也

以上