Home > Solar and Space Plasma (SSP) Seminar | 国立天文台談話会 | 太陽系小天体セミナー | 理論コロキウム > 2018.10.08-10.14

2018.10.08-10.14

      

10月9日(火)13:30~15:00  太陽系小天体セミナー    南棟2階会議室  
Oct 9 Tue      Solar System Minor Body Seminar  Conference Room, South Bldg.2F

10月10日(水)13:30~15:00  太陽天体プラズマセミナー   院生セミナー室   
Oct 10 Wed       Solar and Space Plasma Seminar  Student Seminar Room, Subaru Bldg.

10月11日(木)14:00~15:00   理論コロキウム      開発棟3号館3階会議室 
Oct 11 Thu          DTA colloquium    Conference room, Instrument Development Bldg. 3 3F

10月12日(金)16:00~17:00  国立天文台談話会    すばる棟 大セミナー室  
Oct 12 Fri          NAOJ Seminar        Large Seminar Room 

詳細は以下をご覧下さい。

10月9日(火)

キャンパス
三鷹
セミナー名
太陽系小天体セミナー
定例・臨時の別
定例
日時
10月9日(火曜日)13時30分~15時
場所
南棟2階会議室
講演者
大坪貴文

連絡先
 名前:渡部潤一

備考
テレビ会議またはスカイプによる参加も可

10月10日(水)

Campus
Mitaka
Seminar
Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic
Sporadic
Date and time
10 October (Wed), 13:30-15:00
Place
Student Seminar Room, Subaru Bldg.
Speaker
Petr Heinzel
Affiliation
Academy of Sciences of Czech Republic
Title
White-light flares and stellar superflares
Abstract
I will present an overview of observations and modeling of the so-called solar white-light flares (WLF), extending this also to UV continua detected from space. There is a continuing discussion about relevant physical mechanisms which are responsible for solar and stellar WLFs and the main problem is to distinguish between photospheric and chromospheric contributions to the spectral intensity. On the other hand, a purely chromospheric component can be well separated in limb flares where we detected the WLF emission just above the solar limb and this corresponds to the chromospheric heights – I will present also some recent results of numerical RHD simulations with the Flarix code.
Finally, it appeared that also the whole flare loops, both cool (misleadingly called ‘post’ flare loops), as well hot ones, emit in the visible continuum and this was detected by SDO/HMI instrument at loop heights. This latter issue is directly related to a novel idea that also stellar superflares may be partially due to WL loop emission (Heinzel & Shibata 2018).

Facilitator
-Name:Shin Toriumi

Comment

10月11日(木)

Campus
Mitaka
Seminar
DTA colloquium
Regularly Scheduled/Sporadic
Sporadic
Date and time
Oct. 11, 2018, 14:00-15:00
Place
Conference room, Instrument Development Bldg. 3 3F

Speaker
Hector O. Silva
Affiliation
Montana State University
Title
Illuminating the strong-field regime of gravity
Abstract
Observation of the x-ray pulse profile emitted by hotspots on the surface of neutron stars offers a unique tool to measure the properties of these objects, including their masses and radii. The x-ray emission takes place at the star’s surface, where the gravitational field is strong, making these observations an incise probe into the spacetime curvature generated by these stars. In this presentation, I will discuss how general relativity plays a key role in the accurate modelling of pulse profiles and the prospects for testing Einstein’s theory – and some of its contenders – using these observations.

Speaker
George Pappas
Affiliation
Sapienza University of Rome
Title
Testing the Kerr hypothesis with QNMs and ringdowns.
Abstract
The Kerr spacetime that describes all rotating black holes is one of the most important solutions of general relativity. The theoretical and astrophysical significance of this solution cannot be underestimated. For this reason it is of analogous importance to thoroughly test whether the objects that we have identified as the astrophysical incarnations of Kerr black holes are actually that or some alternative exotic compact object that simply mimics aspects of their behaviour. With the advent of gravitational wave astronomy, this is possible by observing the inspiral, merger, and ringdown of binary systems. This talk will discuss some ways that we can use to test for these impostors.

Facilitator
-Name:Tomoya Takiwaki

Comment
in English

10月12日(金)

Campus
Mitaka
Seminar
NAOJ seminar
Regularly Scheduled/Sporadic
Scheduled
Date and time
Friday, Oct 12 16:00-17:00
Place
Large Seminar Room
Speaker
Douglas Gough
Affiliation
IoA, University of Cambridge
Title
“The rotational dynamics of the Sun”
Abstract
The Sun condensed from the interstellar medium 4.6 Gy ago, preserving, in the initial
stages, a memory of the galactic vorticity and magnetic field. How it subsequently
divested itself of almost all of that is one of the most important questions in
asterophysics, yet remains far from being answered. Helioseismology has transformed
our appreciation of the relevant issues, partly by eliminating many of the early
conjectures regarding the Sun’s present kinematical state. From our knowledge so
gained of both the internal angular velocity and the density stratification, multipole
moments of the external gravitational potential have been determined, providing a
crucial test, in the weak-field limit, of General Relativity. A shear layer at the
base of the convection zone, known as the tachocline, exists by dint of the dipolar
vestige of the interior magnetic field, and has probably caused the magnetic axis to
be inclined from the axis of rotation. I propose that the outcome induces a signature
in the geomagnetic field, providing a precise estimate of the rotation rate of the
Sun’s radiative interior. These matters are no doubt of interest to astronomers who
adopt the Sun as a prototype of cool main-sequence stars, but, more importantly in
some minds, provide valuable information about the basic physics at play.

Facilitator
-Name: Nakaya, Hidehiko

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