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2016.3.14-3.20

3月18日(金)13:30~15:00   太陽天体プラズマセミナー    院生セミナー室
Mar 18 Fri    Solar and Space Plasma Seminar   Student Seminar Room, Subaru bldg.

3月18日(金)16:00~17:00  国立天文台談話会   大セミナー室
Mar 18 Fri   NAOJ Seminar          Large Seminar Room

詳細は以下をご覧下さい。

3月18日(金)

Campus
Mitaka
Seminar
Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic
Regular
Date and time
18 March (Fri), 13:30-15:00
Place
Student Seminar Room, Subaru Bldg.
Speaker
Patrick Antolin
Affiliation
NAOJ
Title
The Dynamic Nature of the Sun’s Magnetic Atmosphere
Abstract
In this farewell talk to NAOJ I will present a summary of results from my research in the last few years, as well as recent results and the future perspective. The talk will focus on two aspects of the solar corona reflecting its highly dynamic nature: the thermal instability mechanism and (Alfvénic) MHD waves.
Thermal instability is a fundamental instability at work throughout the universe and has detailed observational consequences in the Sun. In particular, coronal rain (rapidly occurring, partially ionised cool and dense plasma) is the direct observational consequence of thermal instability. Increasing observational and numerical evidence suggests that its characteristics such as the amount in the corona, its morphology and its dynamics are intrinsically linked to key aspects of the solar atmosphere, such as the amount of basal heating, the chromosphere-corona mass cycle, the presence of turbulence, instabilities and waves. In particular we have shown that coronal rain offers an insight into the coronal heating agents, the local substructure and the global topology of the coronal magnetic field.
Magnetohydrodynamic (MHD) waves are interesting agents ubiquitously present in the solar atmosphere through which several aspects of the observed heating, dynamics and morphology may be explained. Recently we have shown that a subset of these waves, known as transverse MHD waves, can lead to fine-scale structure, braiding, heating, characteristic Doppler motions and line broadening through the combination of resonant absorption and dynamic instabilities. Such combination may allow an efficient conversion of the wave energy into thermal energy through viscous and resistive dissipation in the generated turbulence. In the second part of my talk I will present recent developments of this model, how it can explain recent observations of decay-less coronal loop oscillations and several of the observed features in chromospheric spicules. A possible extension to Alfvenic vortex shedding in prominences will also be discussed.
Facilitator
-Name:Shin Toriumi

3月18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
定例
日時
3月18日(金) 16:00-17:00
場所
大セミナー室
講演者
Alvio Renzini
所属
National Institute of Astrophysics (INAF), astronomical observatory of Padova, Italy
タイトル
The dominance of quenching through cosmic times
Abstract
The evolution with cosmic time of the star formation rate density (the Lilly-Madau plot) and of the “Main Sequence” star formation rate–stellar mass relation are two well established observational facts. In this seminar the implications of these two relations combined are analytically explored, showing that quenching of star formation must start already at very early cosmic times and the quenched fraction then dominates ever since over the star forming one. Thus, a simple picture of the cosmic evolution of the global star formation rate density is derived, in terms of the interplay between star formation and its quenching.
連絡先
-名前: 阿久津 智忠

以上

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