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2017.7.17-7.23


7月 18日(火)13:30~15:00  太陽系小天体セミナー     南棟2階会議室
Jul 18 tue       Solar System Minor Body Seminar Conference Room, South Bldg.2F

7月 18日(火)16:00~17:00  国立天文台談話会       大セミナー室 
Jul 18tue        NAOJ Seminar             Large Seminar Room

7月 19日(水)13:30~14:30  理論コロキウム        コスモス会館会議室
Jul 19 wed       DTA colloquium         Conference Room Cosmos Lodge

7月 21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 21 fri       Solar and Space Plasma Seminar Student Seminar Room, Subaru Bldg.                 

7月 21日(金)16:00~17:00  国立天文台談話会       大セミナー室                        
Jul 21 fri       NAOJ Seminar             Large Seminar Room                    

詳細は以下をご覧下さい。

7月18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
7月18日(火曜日)13時30分~15時
場所
南棟2階会議室
講演者
渡部潤一

講演者
Eleni Petrakou
所属
Center for Axion and Precision Physics Research, Institute for Basic Science (CAPP/IBS)
タイトル
A deterministic model for forecasting long-term solar activity
Abstract
The successive long-term increase and decrease in Sun’s activity associated with solar cycles has not been connected to a definite underlying mechanism so far, hence predictions about its amplitude usually depend on extrapolation from the sunspot number of previous cycles or observations of the geomagnetic field, becoming available only very close to or after a cycle’s start and often departing from the actual events. Here we present a phenomenological model for quantitative description of the cycles’ characteristics in terms of the number of M-class flares. The main element of the model is the relative ecliptic longitude of the planets Jupiter and Saturn. Using as input the temporal distribution of M-class flares during cycle 21, we obtain distributions for cycles 22-24 in notable agreement with the observed ones, and provide predictions for the evolution of solar activity for the rest of cycle 24 and for cycle 25. This deterministic description could contribute to elucidating the underlying physical mechanism and forecasting space weather. (astro-ph:1702.00641)

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18日(火)

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
7月18日(火) 16:00-17:00
場所
大セミナー室
講演者
Chien-Hsiu Lee
所属
NAOJ
タイトル
Time-domain studies of M31
Abstract
ALMA’s first 5 years have brought substantial progress toward the study of distant dusty star forming galaxies (DSFGs). I will present results from two ongoing studies: The ALMA Frontier Fields Survey (ALMA-FFs) and the Bright ALMA Survey In the CDF-S (BASIC). ALMA-FFs is a blind shallow 1.1mm survey of the central regions of 6 strong lensing clusters, while BASIC aims to character sources from a deep SCUBA2 imaging campaign. I will present a census of the detected (and undetected) objects and place them in the context of DSFGs studies to date.

連絡先
-名前:矢野 太平

7月19日(水)

Campus
Mitaka
Seminar
DTA colloquium
Regularly Scheduled
Date and time
19, July, 2017, 13:30-14:30
Place
Conference Room, Cosmos Lodge
Speaker
Shinsuke Takasao
Affiliation
Nagoya University
Title
MHD Simulations of Accretion onto Star from Surrounding Disk
Abstract
(optional)
Facilitator
-Name:Tomoya Takiwaki

Comment
in English

7月日21日(金)

Campus
Mitaka
Seminar
Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic
Regular
Date and time
21 July (Fri), 13:30-15:00
Place
Student Seminar Room, Subaru Bldg.
Speaker
Juan Pedro Cobos Carrascosa
Affiliation
Institute of Astrophysics of Andalusia
Title
An electronic inverter of the radiative transfer equation
Abstract
SO/PHI (/Solar Orbiter /Polarimetric and Helioseismic Imager) is a filtergraph-based, solar magnetograph aimed at mapping the vector magnetic field and the line-of-sight (LOS) velocity of the solar photospheric plasma. It belongs to the scientific payload of the European Space Agency’s /Solar/ /Orbiter/ mission which will orbit the Sun at 0.28 astronomical units.
The limited telemetry rate combined with the large amount of scientific information retrieved by the SO/PHI instrument demand a sophisticated on-board data reduction and scientific analysis through the study of the polarization state of a specific spectral line. The main aim is to perform the complicated algorithm needed to translate the polarization state of the light spectrum in terms of some specific solar parameters like the magnetic field vector and velocity. Technically speaking, the inference of the solar physical quantities through a spectropolarimetric study is based on the inversion of the Radiative Transfer Equation (RTE) and these tasks require the processing of a huge quantity of data in parallel.
The RTE inverter is the core of the on-board scientific data analysis and, probably, one of the most innovative parts of the instrument. Due to the unavailability of qualified for space processors, DSPs, or GPGPUs that fulfil the stringent computational requirements with the limited room and power consumption allocated to the instrument, a specifically designed hardware device has been implemented in SO/PHI. This device is in charge of inverting the RTE aboard /Solar Orbiter /under narrow time and power constraints.
With that goal in mind, we propose a high-performance computing architecture for carrying out the RTE inversion using FPGA devices embedded in the SO/PHI instrument. This architecture on a Virtex-4 FPGA squeezes the FPGA resources in order to reach the time constraints. It is focused in exploiting the data parallelism using several processors working together and using different data streams.
The achieved FPGA systems improve the time and power consumption of ground-based systems based on commercial CPUs.
Finally, the RTE inverter could be used for doing “quick look” in the American Daniel K. Inouye Solar Telescope (DKIST). This device will enable real-time observations of the magnetic field and line-of-sight velocities by using a device based on FPGAs.

Facilitator
-Name:Shin Toriumi
Comment

7月日21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
7月21日(金) 16:00-17:00
場所
大セミナー室
講演者
Ryan M. Lau
所属
JPL
タイトル
High Energy, Cool Transients: Investigating Infrared-Luminous Outbursts with Spitzer
Abstract
The Spitzer Space Telescope is pioneering the exploration of infrared (IR) luminous transients. In our Spitzer InfraRed Intensive Transients Survey (SPIRITS), we are conducting a systematic search of 200 nearby galaxies for IR-luminous outbursts that elude detection in traditional optical surveys. In this talk, I will present two puzzling discoveries from SPIRITS and discuss open questions and the plans to address them.

SPIRITS has revealed a new class of obscured, red transients with mid-IR luminosities between novae and supernovae that do not exhibit optical counterparts. We call them SPRITEs (eSPecially Red Intermediate-luminosity Transient Events). The key to disentangling the various possible physical origins of SPRITEs is IR spectroscopy, which can only be obtained with the unprecedented sensitivity of the upcoming James Webb Space Telescope (JWST). I will discuss possible SPRITE origins and the JWST Guaranteed Time Observation (GTO) program I am leading to determine their nature.

In SPIRITS, we serendipitously discovered variable mid-IR counterparts of ultraluminous X-ray sources (ULXs). A ULX is an off-nuclear point source showing extreme, super-Eddington X-ray luminosities thought to be driven by accretion onto a compact object in a close binary undergoing Roche Lobe overflow. We attribute the mid-IR emission to a circumbinary dust disk produced by the outflow from the supergiant donor star, but the nature of the variability is still uncertain. I will discuss the work I have lead on dusty ULXs and highlight the importance of coordinated multi-wavelength observations.

連絡先
-名前:矢野 太平

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