カテゴリー: Solar and Space Plasma (SSP) Seminar

Solar and Space Plasma (SSP) Seminar

2023.11.6~2023.11.12

　　

November 　6　 Mon 13:30-15:00 Solar and Space Plasma Seminar hybrid; Subaru Building / Insei Seminar Room or Zoom　　　　　　　　　　　　　　

November 　7　Tue　　9:00-12:00 　　

SOKENDAI Doctoral Thesis Preliminary Evaluation 総研大博士学位論文予備審査会
Lecture Room and Zoom&Large Seminar Room and Zoom　　　　　　　

November　7　Tue　10:00-11:30 　　太陽系小天体セミナー zoom

November　8　Wed　10:30-12:00　　 SOKENDAI Colloquium Large Seminar 　　　　　Room in Subaru Building and Zoom

November　10　Fri　16:00-17:00　　 NAOJ Seminar Zoom/Large Seminar Room(hybrid)

詳細は下記からご覧ください。

=============== November 　6 Mon===============

Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Scheduled
Date and time：6th November (Mon), 13:30-15:00
Place： hybrid; Subaru Building / Insei Seminar Room or Zoom
Speaker：Brigitte Schmieder
Affiliation：Observatoire de Paris, LESIA, France
Title：Solar jets observed by IRIS and high spatial resolution ground-based telescopes
Abstract：Solar jets have been observed over a large range of temperatures and wavelengths, from Hα for more than 50 years, to X-rays since the launch of the Yohkoh satellite in 1991. Several characteristics have been derived about their velocities, their rates of occurrence, and their relationship with CMEs. However, the initiation mechanism of jets, e.g. emerging flux, flux cancellation, or twist, is still debated. The high spatial resolution of IRIS and ground-based telescopes (SST,GST) allows us to make a step forward in understanding the relationship of cool and hot jets. Combining IRIS data with vector magnetograms we were able to study the magnetic environment favorable for the occurrence of jets. We searched for possible sites of reconnection by analyzing the magnetic topology.
We found that the magnetic reconnection site can be located at a null point in the corona as well as in a bald patch region forming a current sheet. The IRIS spectra provide evidence of bilateral flows at the reconnection site, due to a transfer of twist from a flux rope to the jet. We detected the presence of cool plasma and hot plasma during the jet formation, including ejections of blobs with speeds reaching super Alfvénic flows of the order of 300 km/s.

Facilitator
-Name：Takayoshi oba
Comment：in English

=============== November 　7 Tue===============

Campus：Mitaka
Seminar：SOKENDAI Doctoral Thesis Preliminary Evaluation 総研大博士学位論文予備審査会
Regularly Scheduled/Sporadic：Sporadic
Date and time：November 7, 2023　9:00～12:00

Place 1：Lecture Room and Zoom

Speaker：
9:00-9:40　Raiga Kashiwagi
Title：Instability and Evolution of Shocked Clouds Formed by Collisions between Filamentary Molecular Clouds

Speaker：
10:00-10:40　Yui Kasagi
Title：Unveiling Atmospheric Features of Faint Substellar Companions from High-Resolution Near-Infrared Spectra

Speaker：
11:00-11:40　Takaho Masai
Title：A Study on the Design of Receiver Optics and Waveguide Components Towards High-Performance (Sub)millimeter Wave Multibeam Receivers

Place 2：Large Seminar Room and Zoom

Speaker：
9:00-9:40　Rikuto Omae
Title：Probing the Magnetic Fields of Distant Galaxies to Unravel the Evolution of Galactic Magnetic Fields

Speaker：
10:00-10:40　Yuta Tashima
Title：Elucidation of Galactic Magnetic Field Structure by Pseudo-Observation Focusing on Depolarization

Facilitator
-Name：Nozomu Tominaga, Hideyuki Kobayashi, Natsuko Fujii (Graduate Student Affairs Unit)

=============== November　7 Tue==============

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7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

=============== November　8 Wed==============

Campus：Mitaka
Seminar：SOKENDAI Colloquium
Regularly Scheduled/Sporadic：Regular
Date and time：November 8, 2023 10:30-12:00
Place：Large Seminar Room in Subaru Building and Zoom

Speaker: Shunsuke Sasaki
Affiliation: SOKENDAI 4th year (D2) (Supervisor: Tomoya Takiwaki, Mami Machida, Takashi Moriya)
Title: Developing “1D+” simulation of core-collapse supernovae

Speaker: Raiga Kashiwagi
Affiliation: SOKENDAI 5th year (D3) (Supervisor: Kazunari Iwasaki, Tomoya Takiwaki, Doris Arzoumanian)
Title: Instability and Evolution of Shocked Clouds Formed by Collisions between Filamentary Molecular Clouds

Facilitator
-Name：Matsuda, Graduate Student Affairs Unit

=============== November　10 Fri==============

Campus：Mitaka
Seminar：NAOJ Seminar
Regularly Scheduled/Sporadic：Regular
Date and time：November 10, 2023 16:00-17:00
Place：Zoom/Large Seminar Room (hybrid)

Speaker：Prof,Yasuhito Sekine
Affiliation：Earth-Life Science Institute

Title：Detection of phosphate in Enceladus’ ocean and comparative chemical evolution in the Solar System
Abstract:
Planetary habitability can be defined as a planetary-scale system that can develop and sustain ingredients of life—liquid water, organics, and energy—over geological time. In this regard, Enceladus possesses a habitable world beneath the icy shell. This moon has a global subsurface ocean interacting with a rocky core, and a wide variety of organic matter and chemical energy supported by hydrothermal activities are available. Among the major bioessential elements for Earth’s life, phosphorus (P) is usually the least abundant in natural aqueous systems and has been a limiting nutrient of primary productivity over Earth’s history. It has been unknown whether this essential element is available in Enceladus. Here we report the discovery of phosphate in ice grains emitted by Enceladus based on the analysis by Cassini’s Cosmic Dust Analyser. Our observational results are evidence that phosphorus is readily available in Enceladus’ ocean, with anomalously high concentrations–at least 100 times higher than Earth’s oceans. To understand the causative mechanism of the enrichment of phosphate, we performed hydrothermal experiments and geochemical modeling. We find that alkaline (pH ~10) and carbonate-rich aqueous environments are essential for the phosphate enrichment, where calcium phosphate minerals are thermodynamically unstable compared to calcium carbonate minerals. Such alkaline carbonate-rich aqueous environments are commonly achieved in icy ocean worlds beyond the CO2 snowline of the Solar System. Phosphate could have been also enriched in similar alkaline carbonate-rich aqueous environments on early Earth, where earliest life on Earth might have utilized phosphorus as components of its building materials.

Facilitator
-Name：Okamoto, Takenori


2023.10.9-2023.10.15

Oct 10 Tue 　　　 10:00-11:30 　　　太陽系小天体セミナー Zoom

Oct 11 Wed 　　　13:30-15:00 Solar and Space Plasma Seminar 　 hybrid; Subaru Building / Insei Seminar Room or Zoom

Oct 11 Wed 　　　14:00-15:00 　 Tea Talk 輪講室（＋Zoom）

Oct 11 Wed 　　　14:30-15:30 　　 ALMA-J seminar hybrid (ROOM102 in ALMA building and ZOOM)

Oct 11 Wed 　　　15:30-16:30 　　 NAOJ Science Colloquium Zoom / the large seminar room (hybrid)

Oct 13 Fri 　 16:00-17:00 NAOJ Seminar zoom/ Large seminar room in Subaru Building

詳細は以下をご覧下さい。

=============== October　10　Tue===============

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10日（火曜日）10時00分～11時30分
場所：zoom
講演者：秋澤宏樹

Abstract：『COMETS III』より、著者による先行公開されている２つの章、
「彗星大気の化学」
https://www.research.ed.ac.uk/en/publications/chemistry-of-comet-atmospheres
「遠隔観測による彗星核の物理・表面特性」
https://arxiv.org/abs/2304.09309
の内容を紹介したいと思います。

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

=============== October　11　Wed===============

Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Scheduled
Date and time：11th Oct (Wed), 13:30-15:00
Place： hybrid; Subaru Building / Insei Seminar Room or Zoom
Speaker： Stanislav Gunar
Affiliation：Astronomical Institute of the Czech Academy of Sciences
Title：What is important for robust inversions of spectroscopic observations of chromospheric and coronal structures?
Abstract：In this presentation, we will discuss what is hidden behind the term “robust spectroscopic inversions” and what we need to achieve them. We will focus on the use of UV spectral data, such as the Lyman line series and the Mg II h&k lines.

There are several necessary ingredients needed to produce high-fidelity spectroscopic inversions. The first is high-resolution multi-wavelength observations. The second are realistic radiative transfer models encompassing dominant processes forming the observed spectra. The third component is sophisticated inversion methods that allow us to find a realistic fit between the observed and synthetic spectra. And there is another necessary component – a good understanding of all important boundary conditions.

We will demonstrate the importance of boundary conditions on the example of the so-called incident radiation. This is the radiation coming from the solar surface, which illuminates chromospheric and coronal structures, such as prominences or spicules. We will show that variations in this boundary condition have a strong impact on the shape and intensity of Lyman lines and the Mg II h&k lines. This impact is then responsible for significantly different outcomes of spectroscopic inversions.

Facilitator
Name：Takayoshi oba
Comment：in English

=============== October　11　Wed===============

キャンパス：三鷹　野辺山 水沢 岡山 ハワイ
セミナー名：Tea Talk
定例・臨時の別：臨時
日時：10/11（水）14：00～15：00
場所：輪講室（＋Zoom）
講演者：渡部　潤一
所属：天文情報センター
タイトル：APRIM2023の顚末記

世話人の名前：藤田登起子

=============== October　11　Wed===============

Campus: Mitaka
Seminar: ALMA-J seminar
Date and time: Oct 11th (Wed) 14:30-15:30
Place: hybrid (ROOM102 in ALMA building and ZOOM)
Speaker: Tetsu Kitayama
Affiliation: Toho University
Title: High-resolution measurements of the Sunyaev-Zel’dovich effect toward galaxy clusters
Abstract:
The Sunyaev-Zel’dovich effect (SZE) provides a unique probe of cosmic plasma up to high redshifts. We first review briefly the progress of high-resolution SZE observations over the past two decades. We then present the measurements made by the Atacama Large Millimeter/submillimeter Array (ALMA); we have obtained SZE images toward four galaxy clusters with 5″ resolution, while retaining extended signals out to 40″. We also discuss implications of these results on the evolution of galaxy clusters as well as prospects for further SZE measurements.

=============== October　11　Wed===============

Campus：Mitaka
Seminar：NAOJ Science Colloquium
Regularly Scheduled/Sporadic：Every Wednesday Date and time：2023 Oct. 11, 15:30-16:30
Place：Zoom / the large seminar room (hybrid)

Speaker：Daichi Kashino
Affiliation：NAOJ
Title：Witnessing Galaxies Reionizing the Intergalactic Medium with JWST
Abstract：
Cosmic reionization is the last major phase transition of the universe, occurring in the first billion years after the Big Bang.
Understanding this process is one of the pivotal goals in modern astrophysics. The commissioning of JWST heralded a new era in investigating the roles of galaxies in reionizing the intergalactic medium, thanks to its unprecedented high sensitivity and dispersing power in near infrared.

In the presentation, I will present early results from our ongoing EIGER (Emission-line galaxies and Intergalactic Gas in the Epoch of
Reionization) survey, a JWST/NIRCam WFSS campaign in the fields of luminous z>6 quasars. The existence of these background quasars enables us to determine the ionization condition along their lines of sight from analysis of the high signal-to-noise quasar spectra. The primary objective of the project is to characterize the cross correlation between galaxies (as pinpointed by JWST) and the IGM conditions during the tail end of the epoch of reionization. In the first quasar field, we confirmed roughly 150 [OIII]5008-emitting galaxies over the redshift range of z=5.3–6.9. Through analyzing the distribution of these galaxies and the transmission spectrum of this corresponding quasar, we identified individual spatial coincidence between the groups of galaxies and highly ionized regions, as well as a mean excess IGM transmission in both Lyman-alpha and Lyman-beta around ~6 cMpc away from the galaxies at z~6. This is interpreted as direct evidence of local reionization by galaxies — indicating that we are witnessing galaxies reionizing the surrounding IGM. I may also showcase further preliminary results from other quasar fields currently being analyzed.

Facilitator
Name：Haruka Kusakabe
Comment：English

=============== October　13　Fri===============

Campus：Mitaka
Seminar：NAOJ Seminar
Regularly Scheduled/Sporadic：Regularly Scheduled Date and time：2023 Oct 13, 16:00-17:00
Place：zoom/ Large seminar room in Subaru Building

Speaker: Cristian Eduard Rusu, PhD
Affiliation: Axelspace Corporation
Title: Opportunities and Challenges for Space Observations with Commercial Satellites
Abstract：Over the past decade, the number of satellites launched into orbit for commercial
purposes has increased exponentially. Nonetheless, these have had virtually no usage for
astronomical observations, due to the still prohibitive cost of launching large mirrors and
achieving scientific-level tolerances. In recent years however, governments as well as private
companies have become interested in Space Situation Awareness, or gaining insights from
optical monitoring from space of artificial satellites and space debris as faint as the 14th magnitude.
This renewed interest in space observations has the potential of reducing the cost of dedicated
astronomical satellites and bringing them within the reach of commercial companies.
I will explore these topics as experienced from the point of view of Axelspace, a Japanese commercial
satellite manufacturer and provider of satellite imagery.

Facilitator
-Name：Moriya, Takashi

2023.10.2-2023.10.8

October　3　Tue　 10:00-11:30 　　太陽系小天体セミナー　Zoom

October　6　Fri　 14:00-15:30 　　 Solar and Space Plasma Seminar hybrid; Central Building (North) / 310 or Zoom

詳細は下記からご覧ください。

=============== October　3　Tue===============

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3日（火曜日）10時00分～11時30分
場所：zoom
講演者：岩田晴花、上田ゆい、奥野夏樹
所属：産業医科大学
タイトル：DESTINY+ミッションのマルチフライバイ候補天体2005UDの多色測光観測

Abstract：DESTINY+ミッションはふたご座流星群の母天体である小惑星Phaethonをフライバイ観測することを主たる目的とする惑星探査ミッションであるが、Phaethonフライバイの後さらに、いくつかの天体をフライバイするマルチフライバイも見据えて計画中である。
我々はPhaethonの次にフライバイする天体候補のうちの一つである小惑星2005UDが観測好機にあった2018年10月に、スペイン・テネリフェ島テイデ観測所の1.52mカルロス・サンチェス望遠鏡に取り付けられたMuSCAT2を使って2005UDの多色測光観測を実施した。この発表ではその結果を報告する。
2005UDはPhaethonを非常によく似た軌道を持つ近地球小惑星であり、Phaethonからの分裂天体の可能性が示唆されている天体である。

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

=============== October　6　Fri===============

Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Scheduled
Date and time：Oct 6th (Fri) 14:00-15:30
Place： hybrid; Central Building (North) / 310 or Zoom
Speaker：Cosima Breu
Affiliation：University of St. Andrews
Title：A coronal loop in a box: From energy generation to observations

Abstract：A large part of the solar corona is composed of bright arcs of confined plasma, the so-called coronal loops. Far from being monolithic cylindrical structures, coronal loops have a finely structured and dynamic interior. With the help of 3D MHD simulations with MURaM, we investigate the energisation and structure of coronal loops and model the resulting observable emission. With the arrival of new powerful telescopes such as DKIST, increasing attention is being paid to the energy provided by small-scale motions. We study the impact of small-scale motions on energy injection and heating as well as observational signatures. In the next few years, the multi-slit spectrometer MUSE will be available and could provide observations with unprecedented spatial and temporal resolution. I will discuss signatures of energy transport and heating that could be observed with future missions.

Facilitator
-Name：Takayoshi oba
Comment：in English

2023.9.11-2023.9.17

Sep　11　Mon　 　15:00-16:30　　Solar and Space Plasma Seminar
　　　　　　　　　　　　　　　　hybrid; Central Building (North) / 310 or Zoom

Sep　13　Wed　　　　14:30-15:30 　　 ALMA-J seminar 　
　　　　　　　　　　　　　　　　　　　ALMA building #102 / Zoom (hybrid)　　　　　　　　　　　　　　

詳細は下記からご覧ください。

=============== Sep　11　Mon===============

Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Scheduled
Date and time：Sep 11th (Sep), 15:00-16:30
Place： hybrid; Central Building (North) / 310 or Zoom
Speaker：Teodora Mihailescu
Affiliation：Mullard Space Science Laboratory, University College London
Title：Intriguing Plasma Composition Pattern in a Solar Active Region: a Result of Non-Resonant Alfvén Waves?

Abstract：The plasma composition of the solar corona is different from that of the solar photosphere. Elements that have a low first ionisation potential (FIP) are preferentially transported to the corona and, therefore, show enhanced abundances in the corona compared to the photosphere. The level of enhancement is measured using the FIP bias parameter. The highest FIP bias values are typically observed in active regions, but they also vary at sub-active region level. In this work, we use data from the EUV Imaging Spectrometer (EIS) on Hinode to study the plasma composition in an active region following an episode of significant new flux emergence into the pre-existing magnetic environment of the active region. We use two FIP bias diagnostics: Si X 258.375 Å/S X 264.233 Å (formation temperature of 1.5 MK) and Ca XIV 193.874 Å /Ar XIV 194.396 Å (formation temperature of 4 MK). We observe different plasma composition patterns in the newly emerging loops and the preexisting loops (those that had been formed before the flux emergence). This result can be interpreted in the context of the ponderomotive force model, which proposes that the enhancement of low-FIP elements in the corona is generally driven by Alfvén waves. We suggest that the low-FIP elements enhancement pattern observed in the emerging loops could be driven by resonant waves originating in the active region core loops. Conversely, we suggest that the pattern observed in preexisting loops could be driven by non-resonant waves and we discuss potential sources of these waves. This different type of wave activity is what could explain the different patterns of low-FIP elements enhancement in these two sets of loops.

Facilitator
Name：Takayoshi oba
Comment：in English

=============== Sep 13　Wed==============

Campus: Mitaka
Seminar: ALMA-J seminar
Regularly Scheduled/Sporadic: Every Wednesday
Date and time: September 13, 2023 (Wed), 14:30-15:30
Place: ALMA building #102 / Zoom (hybrid)
Speaker: Kaho Morii
Affiliation: The University of Tokyo/NAOJ
Title: Unveiling Early Stages of High-Mass Star Formation: Insights from Infrared Dark Clouds

Abstract:
Physical properties in infrared dark clouds (IRDCs) provide insights into the initial conditions of high-mass star and stellar cluster formation. We have conducted the ALMA Survey of 70 µm Dark High-mass Clumps in Early Stages (ASHES) on thirty-nine high-mass clumps, which are the dense parts of IRDCs. These targets are dark at 24 µm and 70 µm and have low temperatures, high masses, and high density, best candidates to investigate the earliest stages of high-mass star formation. Our ALMA observations reveal their internal structure and have identified an unprecedented number of 839 cores from dust continuum emission.  We find that less than 1% (7/839) of the cores possess masses exceeding 27 Msun. All of these cores are gravitationally bound and associated with molecular outflows. No high-mass prestellar core has been observed. Furthermore, among our sample, 90%  (35 out of 39) only host low- to intermediate-mass cores, indicating the necessity of additional mass input for high-mass star formation. Observed core properties generally follow the thermal Jeans fragmentation of the clumps. In this talk, I will present the first results of the statistical study of the 839 cores as well as a summary of the pilot survey, and discuss the characteristics of the initial stages of high-mass star formation.

Facilitator: Bunyo Hatsukade and Kouichiro Nakanishi

2023.8.28-2023.9.3

August　30　Wed　 　13:30-15:00　　Solar and Space Plasma Seminar
　　　　　　　　　　　　　　　　　　　　 hybrid; Central Building (North)310 or Zoom

August　30　Wed　　　14:30-15:30 　　 ALMA-J seminar 　
　　　　　　　　　　　　　　　　　　　　 Zoom / ALMA building #102 (hybrid)　　　　　　　　　　　　　　　

詳細は下記からご覧ください。

=============== August　30　Wed===============

Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Scheduled
Date and time：Aug 30th (Wed), 13:30-15:00
Place： hybrid; Central Building (North) / 310 or Zoom
Speaker：Dr. Masahito Kubo
Affiliation：NAOJ
Title：Comparison of polar magnetic fields derived from MILOS and MERLIN inversions for Hinode/SOT-SP data


Abstract：The detailed investigation of the polar magnetic field and its time evolution is one of the major achievements of Hinode. Precise measurements of the polar magnetic field are essential for understanding the solar cycle, and they provide important constraints for identifying the source regions of the solar wind. The Spectropolarimeter (SP) of the Solar Optical Telescope (SOT) on board Hinode has been the instrument best suited to make such measurements. In this study, we compare SOT-SP data for the polar regions as processed using two representative Milne-Eddington inversion codes, MILOS and MERLIN. These codes are applied to the same level-1 SOT/SP data, and the same disambiguation algorithm is used on the maps that go through the two inversions. We find that the MERLIN inversion tends to give the radial magnetic flux density (the magnetic flux density with respect to the local vertical) that is about 20% larger than the MILOS inversion. The somewhat higher radial magnetic flux density from MERLIN appears to be common to the polar magnetic fields observed at different phases of the solar cycle. We attribute the difference in the radial magnetic flux density to different filling factors adopted by the two inversions, based on different assumptions of the scattered light profiles. The relationship between the radial magnetic flux density and the magnetic filling factor could be more complex in the polar (limb) observations due to the possible contributions of the transverse magnetic field component that may affect the estimated radial magnetic flux density.

Facilitator
-Name：Takayoshi oba
-Comment：in English

=============== August 　30　Wed==============

Campus: Mitaka
Seminar: ALMA-J seminar
Regularly Scheduled/Sporadic: Every Wednesday
Date and time: August 30, 2023 (Wed), 14:30-15:30
Place: ALMA building #102 / Zoom (hybrid)
Speaker: Jan-Willem Steeb
Affiliation: National Radio Astronomy Observatory
Title: AstroHACK: Holography Antenna Commissioning Kit

Abstract: Correcting the surface of a dish antenna by adjusting the panels can significantly improve the dish’s performance. For instance, the VLA panel adjustments completed in 2000 more than doubled the high-frequency sensitivity of the VLA dishes. The software presently utilized by ALMA and VLA is written in Fortran and is becoming challenging to maintain. Consequently, the CASA team is developing AstroHACK, which generates antenna aperture images and calculates antenna panel adjustment corrections from calibrated holography measurement sets. AstroHACK is the first non-prototype software package developed using the Python-based VIPER (Visibility and Image Parallel Execution Reduction) Framework, previously known as the CASA Next Generation Infrastructure Software Framework. This framework was designed to meet the requirements of the ngVLA and the ALMA Wideband Sensitivity upgrade. In this seminar, I will provide an overview of the VIPER Framework and the functionalities of AstroHACK, followed by a live demonstration.