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2016.7.4-7.10

7月4日(月)13:30~15:00  太陽系小天体セミナー   南棟2階会議室
Jul 4 mon           Solar System Minor Body Seminar   Conference Room, South Bldg.2F   

7月6日(水)13:30~14:30  理論コロキウム   コスモス会館会議室 
Jul 6 wed    DTA colloquium        Conference Room, Cosmos Lodge

7月7日(木)15:00~16:00  VLBIコロキウム    中央棟(南)2階VLBIセミナー室
Jul 7 thu    VLBI Colloquium      VLBI Seminar Room, Main Bldg. (South) 2F

7月8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
Jul 8 fri  Solar and Space Plasma Seminar   Student Seminar Room, Subaru Bldg.

詳細は以下をご覧下さい。

7月4日(月)

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
7月4日(月曜日)13時30分~15時
場所
南棟2階会議室
講演者
塚田健

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

7月6日(水)

Campus
Mitaka
Seminar
DTA colloquium
Regularly Scheduled/Sporadic
Regularly Scheduled Date and time:06 July 2016, 13:30-14:30
Place
Conference Room, Cosmos Lodge
Speaker
Shota Kisaka
Affiliation
Aoyama Gakuin University
Title
Engine-powered macronovae
Abstract
In 2015, a gravitational-wave (GW) signal was directly detected from a merger of a binary black hole (BH) for the first time. GW signals are expected to be generated not only by mergers of binary BHs, but also by mergers of neutron star (NS) binaries (NS-NS and BH-NS binaries). NS binary mergers may also power bright electromagnetic (EM) signals, because the ejection of normal matter during mergers is thought to be responsible. EM counterparts have been focused on to maximize the scientific return from the detection of GWs. One of the most promising EM signatures are macronovae (or kilonovae): approximately isotropic emissions from heated merger ejecta. Although the r-process radioactivity is widely discussed as an energy source, it requires a huge mass of ejecta from a NS binary merger to explain the observed macronova candidates. As an alternative, we propose that macronovae are energized by the central engine, i.e., a BH or NS, and the injected energy is emitted. The engine model allows a wider parameter range, especially smaller ejecta mass than the r-process model. We also discuss the implications for the engine-powered model for the search of EM counterparts to GWs.
Facilitator
-Name:Tomoya Takiwaki

Comment
in English

7月7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
7月7日(木曜日)15時~16時
場所
中央棟(南)2階VLBIセミナー室
講演者
Kazuhito Motogi
所属
Mizusawa VLBI Observatory
タイトル
KaVA open-use monitoring of the extremely high-velocity water maser jet in G357.967-0.163
Abstract
 In our previous studies, we have shown that a blue-shifted dominated and highly variable water maser source, G353.273+0.641 (G353), is associated with a nearly face-on accretion system in high mass star-formation. Such a system is essential target to study the innermost accretion mechanism in ALMA era, however, still quite rare and we must increase target samples for statistical discussions.
 We have recently started new KaVA open-use project that intends to confirm a nature of G357.967-0.163 that is found to be the second candidate of ‘G353-type’ object. Two main science goals are, (1) Directly confirming a face-on geometry of the system via proper motion measurements. (2) Studying time variability of maser distribution among maser flare events. We will compare inclination angles between G353 and G357, in order to test how geometrical difference affect properties of maser spectrum. We also search for a signature of recurrent shock propagation, accompanied by drastic changes of maser distribution near the root of the jet as seen in G353. Such a time-dependent activities reflect episodic jet-launching activities and allow us to compare physical conditions at the innermost disk region between G353 and G357.
 In this talk, I will report on project overview, basic source information and preliminary results of the first 3 epochs.

連絡先
-名前:倉持一輝

備考
英語、テレビ参加可

7月8日(金)

Campus
Mitaka
Seminar
Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic
Regular
Date and time
8 July (Fri), 13:30-15:00
Place
Student Seminar Room, Subaru Bldg.
Speaker
Masahito Kubo and CLASP team
Affiliation
NAOJ
Title
Ubiquitous Fast Propagating Intensity Disturbances in Solar Chromosphere
Abstract
High cadence observations by a slit-jaw (SJ) optics of a sounding rocket experiment named Chromospheric Lyman Alpha SpectroPolarimeter (CLASP) reveal that intensity disturbances with an amplitude of 2-5% recurrently propagate along the bright elongated structures in the chromosphere or transition region at a speed of 150-350km/s.
The CLASP/SJ instrument provides us a time series of 2D images with Ly-alpha broadband filters at a 0.6 s cadence. The fast propagating intensity disturbances are observed in the quiet Sun and an active region, and at least 20 events are clearly detected in the field of view of 527″x527″ during just 5-minute observation.
The intensity disturbances tend to propagate away from areas with strong photospheric magnetic fields. The fast propagating intensity disturbances may be related magnetic canopy structures. We confirm that the intensity disturbances propagating along the slit are also observed by the spectropolarimeter of CLASP. On the other hand, no significant Doppler shift > 150km/s is detected in the period when intensity disturbances across the slit in CLASP/SJ images.
In addition, the Doppler velocities measured with the Si III line
(120.65nm) is just less than ±10km/s in this period. No significant Doppler shrift suggests the fast propagating intensity disturbances correspond to motion of intensity patterns like waves rather than plasma motion. The intensity fluctuations propagating at about the Alfven speed suggest a magnetohydrodynamic fast mode waves. One issue on the possibility of the fast mode wave is that the intensity disturbances do not propagate uniformly toward all the directions, but a part of the wave may be only detected because bright and long structures are needed to catch the faint intensity fluctuations propagating at very high speed.

Facilitator
-Name:Shin Toriumi

Comment

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