Nov 1 Tue 10:00～11:30 太陽系小天体セミナー Zoom
Nov 2 Wed 10:30～12:00 SOKENDAI Colloquium Zoom
Nov 2 Wed 14:30～15:30 ALMA-J seminar Zoom
Nov 2 Wed 15:30～17:00 NAOJ Science Colloquium Zoom/Instrument Development Bldg. 3
Nov 4 Fri 13:30～15:00 Solar and Space Plasma Seminar Zoom/Insei Seminar Room
Nov 4 Fri 16:00～17:00 NAOJ Seminar Zoom/Large Seminar Room
詳細は以下をご覧下さい
11月1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：11月1日（火曜日）10時00分～11時30分
場所：zoom
講演者：佐藤幹哉
世話人の連絡先
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
11月2日（水）
Campus：Mitaka
Seminar：SOKENDAI Colloquium
Regularly Scheduled/Sporadic：Regular
Date and time：November 2, 2022 10:30-12:00
Place：Zoom
Speaker : Shun Ishigami
Affiliation: SOKENDAI 2nd year (M2) (Supervisor: Hirohisa Hara, Yukio Katsukawa, Masahito Kubo)
Title: Observational Study of Coronal Loops Using Spectroscopic Data
Facilitator
-Name：Matsuda, Graduate Student Affairs Unit
11月2日（水）
Campus：Mitaka,
Seminar：ALMA-J seminar
Regularly Scheduled/Sporadic： Every Wednesday
Date and time：2nd November (Wed), 14:30 – 15:30
Place：Zoom
Speaker：Takaho Masai
Affiliation：GUAS/NAOJ
Title：A Study on the Effect of Aberrations on the Design of High-Aperture Efficiency Optics for (Sub)Millimeter Multibeam Receivers.
Abstract：
Multibeam heterodyne receivers and their capabilities for wide-field observations have been identified as one mid-term upgrade opportunity for ALMA towards the 2030s. To develop a highly sensitive multibeam receiver, we must carefully design receiver optics with high aperture efficiency. However, the off-axis multibeam receiver pixels will suffer from the effect of aberrations and thus lower the aperture efficiency. The effect of aberrations has not been considered when designing the multibeam receiver optics which has led to some approximations for the aperture efficiency such as using the Strehl ratio from optics. The purpose of this study is to investigate the effect of aberrations on the design of the multibeam receiver optics towards developing a method to design high-aperture efficiency multibeam receiver optics. In this talk, I will introduce the relation between aberrations and aperture efficiency and show some results of the aperture efficiency affected by aberrations for the ALMA antenna.
Facilitator
-Name：Masumi Shimojo, Yu Cheng
11月2日（水）
Campus：Mitaka
Seminar：NAOJ Science Colloquium
Regularly Scheduled/Sporadic：Every Wednesday
Date and time：2022 Nov. 2, 15:30-17:00
Place：zoom / Instrument Development Bldg. 3 (hybrid)
Speaker：Koh Takahashi
Affiliation：Tohoku University
Title：Novel modeling of magneto-rotational stellar evolution
Abstract：While magnetic fields have been considered to influence the evolution of non-degenerate and compact stars, it has become clear in recent years that actually all stars are deeply affected. We propose a new framework of stellar evolution simulation, in which intertwined evolution between the magnetic fields, the stellar rotation, and the stellar structure is treated self-consistently. In this talk, I will report the results of the magneto-rotational evolution of 1.5 M stars, which have radiatively stratified envelopes during their main-sequence. We have found that the Lorentz force aided by the Omega-effect imposes torsional Alfven waves propagating through the magnetized medium, leading to near-rigid rotation within ~Alfven time. Our results of the hydrogen-burning stage can reproduce the main observed properties of Ap/Bp stars, and moreover, calculations continued to the red-giant regime show a pronounced core-envelope coupling, which reproduces the core and surface rotation periods determined by asteroseismic observations. In addition, I will report on the recent progress of developing a 1D scheme for representing the convective dynamo, which accounts for the magnetic activity of convective stars including the sun. Our new approach reproduces the most fundamental properties of this phenomenon, namely the magnetic field amplification as well as the cyclic behavior.
Facilitator
-Name：Akimasa Kataoka
Comment：English
11月4日（金）
Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Scheduled
Date and time：Nov 4th (Fri), 13:30-15:00
Place： hybrid, Subaru Building / Insei Seminar Room or Zoom
Speaker：Ryoko Ishikawa
Affiliation：National Astronomical Observatory of Japan
Title：The sounding rocket experiment CLASP2 for mapping the chromospheric magnetic fields
The magnetic field measurement throughout the solar atmosphere is crucial to understand the energy transfer from the photosphere to the corona, as well as for its dissipation. However, there is an overwhelming lack of information on the magnetic field in upper chromosphere and the above where the magnetic pressure dominates the gas pressure. On April 11, 2019, for the first time, the sounding rocket experiment CLASP2 conducted the high-precision spectropolarimetric observation in near UV around 280 nm including the Mg II h & k and Mn I aiming at the magnetic field measurement in the upper chromosphere. In this talk, I will present the highlights of the CLASP2 results which have demonstrated the diagnostic capability by the UV spectropolarimetery.
Facilitator
-Name：Takayoshi oba
Comment：in English
11月4日（金）
Campus: Mitaka
Seminar: NAOJ seminar
Regularly Scheduled/Sporadic: Every Friday
Date and Time: 2022 November 4 16:00-17:00
Place: Zoom / Large Seminar Room
Speaker: J. Xavier Prochaska（UC Santa Cruz）
Title: Probing the Universe with Fast Radio Bursts
Abstract:
I will review advances in the research of fast radio bursts — millisecond pulses of intense, coherent radio emission — and their applications to studying diffuse gas and magnetic fields across the cosmos. At the start of 2021, nearly every major radio facility is pursuing FRBs. Over 1,000 events have been discovered and ~10 are localized at sub-arcsecond precision to their host galaxies. Our premier ground and space-based observatories are searching for coincident emission and being used to characterize the hosts and foreground galaxies. I will review recent scientific advances in the field with emphasis on using FRBs to successfully disentangle the cosmic web.
Facilitator: 尾崎 忍夫 / Ozaki,Shinobu