カテゴリー: 科学研究部コロキウム

科学研究部コロキウム

2024.7.1-2024.7.7

July 1 Mon 15:00-16:30
Solar and Space Plasma Seminar
hybrid; Insei Seminar Room in Subaru Building and Zoom

July 2 Tue 10:00-11:30
太陽系小天体セミナー (Solar System Minor Body Seminar)
Zoom

July 3 Wed 10:00-12:00
SOKENDAI Colloquium
hybrid; Large Seminar Room in Subaru Building and Zoom

July 3 Wed 15:00-16:30
Solar and Space Plasma Seminar
hybrid; Insei Seminar Room in Subaru Building and Zoom

July 3 Wed 15:30-16:30
NAOJ Science Colloquium
Zoom

詳細は下記からご覧ください。

=============== July 1 Mon===============

Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Sporadic
Date and time：1 July (Mon), 15:00-16:30
Place： Insei Seminar Room and Zoom

Speaker：Dr. Othman Michel Benomar

Affiliation：NAOJ

Title： Constraining Magnetic Activity Latitudes in Sun-like Stars using asteroseismology

Abstract：
I will discuss a recently developed framework for measuring the activity of Sun-like stars and constraining the latitudes of magnetic activity (Benomar et al. 2023). This framework expresses in a phenomenological manner the effects of activity on low-degree pulsation frequencies, which are global standing waves within stars. Due to various effects, a star is not exactly spherical, and neither is the cavity in which those global modes propagate. The main reason for the departure from sphericity of the mode cavities is the centrifugal force. As this effect is proportional to the square of the rotation rate, it becomes increasingly important as rotation increases. Another cause of asphericity is the magnetic field. A strong magnetic field, such as the one observed in the Sun’s active zones and localized in a specific region of the star, changes the propagation path of the waves and eventually results in a perturbation of the overall cavity shapes of global modes.

Here, I will first show that utilizing a simple single-band activity model on Sun-like stars, it is possible to determine the active latitudes of a star. The method is demonstrated to work on solar data
using the VIRGO instrument aboard the SoHo satellite. I will also show that in an ensemble of 103 Kepler stars, many exhibit signs of activity.

The results indicate a complex pattern of activity bands that essentially depend on stellar effective temperature and stellar rotation. This latter work may provide new insights into the longstanding question about the processes surrounding the dynamo mechanism in other stars.

Facilitator
-Name：Akiko Tei

Comment：Japanese (Slides will be in English)

=============== July 2 Tue===============

キャンパス：三鷹
セミナー名：太陽系小天体セミナー (Solar System Minor Body Seminar)
定例・臨時の別：定例
日時：　7月　2日（火曜日）10時00分～11時30分
場所：zoom
講演者：秋澤宏樹
タイトル: 論文紹介
Abstract:
V.Oldani, et al., Comet 81P/Wild 2: changes in the spin axis orientation during the last five apparitions, Accepted for publication on “Icarus”. https://arxiv.org/abs/2405.19975

世話人の連絡先
-名前：渡部潤一

備考：zoomでの参加

===============July 3 Wed==============

Campus：Mitaka
Seminar：SOKENDAI Colloquium
Regularly Scheduled/Sporadic：Scheduled
Date and time：July 03 10:00-12:00
Place：Large Seminar Room in Subaru Building and Zoom

Speaker：Tadashi Hirose
Affiliation：SOKENDAI 1st year (M1) (Supervisor:Noriyuki Narukage, Takashi Sekii, Masumi Shimojo)
Title：Coronal heating associated with filament eruption

Speaker：Shunsuke Sasaki
Affiliation：SOKENDAI 5th year (D3) (Supervisor:Tomoya Takiwaki, Mami Machida, Takashi Moriya)
Title：Progenitor dependence of core-collapse supernovae

Speaker：Yoshihiro Naito
Affiliation：Not entered
Title：Not entered

Facilitator
-Name：Yoshiaki Sato

Comment：Language: English

===============July 3 Wed==============

Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Sporadic
Date and time：3 July (Wed), 15:00-16:30
Place： Insei Seminar Room and Zoom

Speaker：Prof. Petr Heinzel

Affiliation：
Czech Academy of Sciences, Czech Republic
University of Wroclaw, Poland

Title： Do stellar flare fluxes indicate a presence of cool loops ?

Abstract：
On the Sun we routinely resolve the flare ribbons and overlying loop arcades, while stellar fluxes integrate the emission from both. Stellar flare spectra and light curves are usually interpreted in terms of heating of the lower atmospheric layers (ribbons), using the radiation-hydrodynamical simulations (RADYN or FLARIX codes). However, the loop arcades on cool stars are expected to be extended and namely cool loops can thus contribute significantly to flare fluxes. This idea was implemented by Heinzel and Shibata (2018) for Kepler white-light observations. Later on, motivated by TESS observations, MHD simulations of loops have been performed to interpret the observed secondary flare peaks (Yang et al. 2023). The loop arcade was also inferred from time-modulated TESS light curves (Bicz et al. 2023). On the other hand, high-dispersion line spectroscopy shows the signatures of cool-plasma downflows in flare loops which is consistent with the non-LTE radiative-transfer simulations (Wollmann et al. 2023). We will review these new findings and discuss future prospects.

Facilitator
-Name：Akiko Tei

Comment：Japanese (Slides will be in English)

===============July 3 Wed==============

Campus: Mitaka
Seminar: NAOJ Science Colloquium
Date and time: 2024 July 3 (Wed.), 15:30-16:30 JST
Place: Zoom

Speaker: Tetsuya Hashimoto
Affiliation: Department of Physics, National Chung Hsing University
Title: Mysterious fast radio bursts and the new radio telescope in
Taiwan: BURSTT
Abstract:
Fast radio bursts (FRBs) are mysterious coherent radio pulses with millisecond timescales, most of which emerge from galaxies at cosmological distances. Uncovering the origin of FRBs is one of the central foci in astronomy. However, their origin is yet to be known due to the major observational challenge of FRBs: when and where they happen in the sky are unknown. Bustling Universe Radio Survey Telescope in Taiwan (BURSTT) is a new radio array dedicated to detecting mysterious FRBs in the nearby Universe. Within a few years, BURSTT will overcome this observational challenge with its unique capabilities of nearly all-sky monitoring (10,000 deg2) and accurate localization (< 1 arcsec), and none of the current FRB facilities have both of these capabilities.
In this presentation, I will summarize the expected science cases with unique FRB samples of BURSTT. In contrast to the current FRB facilities, BURSTT will observe the same sky as multi-messenger instruments, including gravitational waves and neutrinos. This BURSTT’s design will maximize the chance of the simultaneous detection of multi-messengers or multi-wavelength counterparts, which would strongly constrain the FRB progenitor scenarios. BURSTT will provide a unique window into FRB applications from environments, progenitors, to cosmology.

Facilitator
-Name: Shubham Bhardwaj

Comment: English

2024.6.24-2024.6.30

June 25 Tue 10:30-12:00
Solar and Space Plasma Seminar
hybrid; Seminar Room 310 in Main building (North) and Zoom

June 26 Wed 10:00-12:00
SOKENDAI Colloquium
hybrid; Large Seminar Room in Subaru Building and Zoom

June 26 Wed 14:30-15:30
ALMA-J seminar
hybrid; Room 102 in ALMA building and Zoom

June 26 Wed 15:30-16:30
NAOJ Science Colloquium
hybrid; Rinkoh Seminar Room and Zoom

June 28 Fri 15:30-16:30
NAOJ Seminar
hybrid; Large Seminar Room in Subaru Building and Zoom

詳細は下記からご覧ください。

=============== June 25 Tue===============

Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Sporadic
Date and time：25 June (Tue), 10:30-12:00
Place： Seminar Room 310 in Main building (North) and Zoom

Speaker：Dr. Gabrial Giono

Affiliation：Space Research Institute, Austrian Academy of Sciences, Austria

Title： Plasma and planetary science instrumentation at the IWF: SMILE, Comet Interceptor, JUICE and BepiColombo

Abstract：
The Institut für Weltraumforschung (IWF) in Graz, Austria, has been developing space instruments for more than 50 years. In recent years, the institute has been contributing to a number of plasma and planetary missions. This talk will focus on four missions: (1) the ESA/CAS Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) mission, (2) the ESA Comet Interceptor mission, (3) the ESA JUICE mission, and (4) the ESA/JAXA BepiColombo mission.
An overview of the IWF instrumental contribution for each these four missions will be presented, respectively (1) the EBOX for the Soft X-ray imager, (2) the MANiaC mass spectrometer and DFP flux-gate magnetometers, (3) the MAGSCA scalar optical magnetometer and (4) the PICAM ion mass spectrometer. For each instrument, an in-depth explanation of their working principle will be provided.

Facilitator
-Name：Akiko Tei

Comment：Japanese (Slides will be in English)

=============== June 26 Wed===============

Campus：Mitaka
Seminar：SOKENDAI Colloquium
Regularly Scheduled/Sporadic：Scheduled
Date and time：Jun 26 10:00-12:00
Place：Large Seminar Room in Subaru Building and Zoom

Speaker：Naoya Kitade
Affiliation：SOKENDAI 1st year (M1) (Supervisor:Akimasa Kataoka, Hideko Nomura, Yuka Fujii)
Title：Support for fragile porous dust in a gravitationally self-regulated disk around IM Lup (review of a paper by Ueda et al, 2024 2406.07427)

Speaker：Chiba Rhotaro
Affiliation：Not entered
Title：Not entered

Speaker：Shotaro Tada
Affiliation：SOKENDAI 5th year (D3) (Supervisor:Takayuki Kotani, Yutaka Hayano, Yosuke Minowa)
Title：Exploring Exoplanetary Atmosphere Asymmetries Through Transmission Spectroscopy: Application to JWST NIRSpec/G395H Data of WASP-39 b’s Transit

Facilitator
-Name：Yoshiaki Sato

Comment：Language: English

===============June 26 Wed==============

Campus: Mitaka
Seminar: ALMA-J seminar
Date and time: 2024 June 26 (Wednesday), 14:30-15:30 JST
Place: Room 102 in ALMA building / Zoom (hybrid)
Speaker: Dirk. Petry (European Southern Observatory)

Title: Results from the ALMA internal development study on uv coverage assessment and scheduling

Abstract: This development study started in 2020 and has now submitted its final report to the review panel. In this talk I will present a “sneak preview” of the results which consist mostly of suggestions for adjustments to ALMA scheduling, QA0, and QA2 to achieve better uv coverage and image quality. I will also introduce our new uv coverage QA tool “assess_ms”.

Facilitator
-Name: Pei-Ying Hsieh

===============June 26 Wed==============

Campus: Mitaka
Seminar: NAOJ Science Colloquium
Date and time: 2024 June 26 (Wed.), 15:30-16:30 JST
Place: the rinkoh seminar room / Zoom (hybrid)

Speaker: Shigeo Kimura
Affiliation: Tohoku University
Title: Pursuing Sources of Cosmic High-energy Neutrinos
Abstract:
Cosmic high-energy neutrinos are expected to be a smoking-gun signature to identify the origin of high-energy cosmic rays. IceCube experiment reported detection of cosmic high-energy neutrinos in 2013, the origin of which became a new mystery in astrophysics. In order to identify the cosmic neutrino sources, multi-messenger observational and analysis technics are now rapidly developing. In this talk, I will review the progress of high-energy neutrino astrophysics, discuss high-energy neutrino emission model in radio-quiet active galactic nuclei, and introduce our effort to identify neutrino sources using optical observational data.

Facilitator
-Name: Ryotaro Chiba

Comment: English

===============June 28 Fri==============

Campus：Mitaka
Seminar：NAOJ Seminar
Regularly Scheduled/Sporadic：Regular
Date and time：June 28, 2024 15:30-16:30
Place：Zoom/Large Seminar Room (hybrid)

Speaker：Dr. Jose Luis Gómez
Affiliation：Instituto de Astrofísica de Andalucía

Title：Eyes on the Invisible: Charting New Horizons with the Event Horizon Telescope

Abstract:The Event Horizon Telescope (EHT) collaboration has captured the first image of a black hole’s event horizon in the galaxy M87, and subsequently, in the supermassive black hole at the center of our Milky Way, SgrA. More recently, the collaboration has released the first follow-up image of M87, utilizing observations from April 2018. The EHT has also revolutionized our understanding of the relativistic jets commonly present in active galactic nuclei, revealing the processes governing the jet formation, collimation and acceleration with an unprecedented angular resolution. The upcoming next-generation Event Horizon Telescope (ngEHT) is poised to significantly upgrade the current system by adding new stations and introducing multi-frequency observational capabilities. These will notably improve the ngEHT’s angular resolution, dynamic range, and overall coverage. This expansion is crucial for enabling the ngEHT to create the first movies of black holes, a leap forward in understanding the processes of black hole accretion and the formation of relativistic jets. In addition, the ngEHT’s advanced features will be instrumental in exploring alternative theories to General Relativity and will expand our observational reach to include potentially a dozen new black holes. By adding an orbiting antenna, the Black Hole Explorer (BHEX), a potential NASA mission, will discover and measure the bright and narrow “photon ring” that is predicted to exist in images of black holes, and fully encodes the space-time metric.

Facilitator
-Name：Takashi Moriya

2024.6.10-2024.6.16

June 11 Tue 10:00-11:30
太陽系小天体セミナー (Solar System Minor Body Seminar)
Zoom

June 12 Wed 10:30-12:00
SOKENDAI Colloquium
hybrid; Large Seminar Room in Subaru Building and Zoom

June 12 Wed 15:30-16:30
NAOJ Science Colloquium
hybrid; Large Seminar Room in Subaru Building and Zoom

June 13 Thu 14:30-15:30
ALMA-J seminar
hybrid; Room 102 in ALMA Building and Zoom

June 14 Fri 13:30-14:30
ATCセミナー
hybrid; Large Seminar Room in Subaru Building and Zoom

June 14 Fri 15:30-16:30
NAOJ Seminar
hybrid; Large Seminar Room in Subaru Building and Zoom

June 14 Fri 15:30-17:00
Solar and Space Plasma Seminar
hybrid; Insei Seminar Room in Subaru Building and Zoom

詳細は下記からご覧ください。

=============== June 11 Tue===============

キャンパス：三鷹
セミナー名：太陽系小天体セミナー (Solar System Minor Body Seminar)
定例・臨時の別：定例
日時：　6月　11日（火曜日）10時00分～11時30分
場所：zoom
講演者：和田空大
所属: 東京大学
タイトル: 研究紹介

世話人の連絡先
-名前：渡部潤一

備考：zoomでの参加

=============== June 12 Wed===============

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

Speaker：Takumi Kakimoto
Affiliation：SOKENDAI 3rd year (D1) (Supervisor: Masayuki Tanaka, Daisuke Iono, Kiyoto Yabe)
Title：The role of the environment in quenching of massive galaxies at high redshifts

Speaker：Kazuki Watanabe
Affiliation：SOKENDAI 2nd year (M2) (Supervisor: Tai Oshima, Yoshinori Uzawa, Takafumi Kojima)
Title：Development of a sub-THz MKID Camera for Deep Space Observation

Facilitator
-Name：Yoshiaki Sato

Comment：Language: English

===============June 12 Wed==============

Campus: Mitaka
Seminar: NAOJ Science Colloquium
Date and time: 2024 June 12 (Wed.), 15:30-16:30 JST
Place: the large seminar room / Zoom (hybrid)

Speaker: Mehrnoosh Tahani
Affiliation: Stanford University
Title: Galactic Structure and Evolution: What 3D Magnetic Field Observations Are Revealing
Abstract:
Recent observations have significantly advanced our understanding of the three-dimensional (3D) structure and evolution of the interstellar medium (ISM). To fully comprehend ISM evolution, however, it is necessary to study interstellar magnetic fields, which play a pivotal role in the evolution of the galaxy and the formation of stars. Despite their importance, our understanding of magnetic fields in the ISM is limited due to significant challenges in observing them in 3D. In this talk, I will briefly discuss how we overcame the challenges in determining the 3D magnetic fields associated with giant molecular clouds. These 3D fields enabled us to propose step-by-step scenarios to explain the formation of these clouds, revealing previously undiscovered interstellar structure. Our approach involves a novel technique based on Faraday rotation measurements to detect the line- of-sight component of magnetic fields. We then integrate these line-of-sight measurements with plane-of-sky magnetic field observations to examine the 3D magnetic field morphology associated with the clouds. Finally, we employ Galactic magnetic field models to reconstruct the complete 3D magnetic field morphologies of these clouds, including their previously unknown direction. These 3D studies provide novel constraints on theories for the formation and evolution of star-forming clouds.

Facilitator
-Name: Nanase Harada

Comment: English

===============June 13 Thu==============

Campus: Mitaka
Seminar: ALMA-J seminar
Date and time: 2024 June 13 (Thursday), 14:30-15:30 JST
Place: Room 102 in ALMA building / Zoom (hybrid)
Speaker: Nimesh Patel
Affiliation: Harvard-Smithsonian Center for Astrophysics

Title: Chemical Evolution from AGB stars to Planetary Nebulae: A spectral-line survey of the Egg Nebula (CRL 2688)
Abstract:
Carbon-rich stars on the asymptotic giant branch (AGB) are major sources of gas and dust in the interstellar medium. AGB stars remain
in this stage for 1 to 10 Myrs, and have typical masses of 1–8 Msun and mass loss rates of 10^(−7) to 10^(−4) Msun/yr. During the
brief (∼1000 yr) period in the evolution from the AGB to Planetary Nebula (PN) there is a dramatic change in the morphology from nearly
spherical symmetry to bipolar, quadrupolar and more complex structures.
Because of the brief duration of this Proto-Planetary Nebula (PPN) phase and the poor angular resolution of most prior molecular line
observations (>= 15″– 20″), the physical mechanisms governing the AGB -> PPN -> PN transition and the accompanying chemical processes
are poorly understood.

Using the Submillimeter Array (SMA), we have previously carried out spectral-line surveys of CRL 618, NGC 7027, and IRC+10216. In this
talk, I will present preliminary results from a spectral-line survey of CRL2688 (Egg Nebula), which is a well known PPN with multiple
outflows and shell-like structures discovered in HST images.
Together, these unbiased surveys of the 4 prototypical carbon rich objects which span the evolutionary sequence from the AGB to fully
formed planetary nebula — IRC+10216 (AGB), CRL 2688 (early PPN), CRL 618 (PPN) and NGC 7027 (PN) — have the potential of unravelling
the physical and chemical evolution of circumstellar envelopes from AGB to PN.

The SMA line survey of CRL 2688 covers the frequency range of 224–266 GHz, with an rms noise level of 100~150 mJy/beam in 1 km/s
wide channels. About 130 lines are detected in the 42 GHz coverage; all the detected lines have been identified. Lines of silicon
bearing species such as SiCC and SiS are much weaker (compared to those seen in IRC+10216). Several lines show morphological features
corresponding to the multiple outflows in this source (HCN, CS), and the disk like structure (CH3CN,SiS). The channel maps show an
S-shaped morphology for the bipolar lobes in CS and HCN, clear indication of a precessing/wobbling jet or two jets with different
axes. It is interesting to see Si bearing molecules, and weak lines of c-C3H2 in CRL 2688, whereas this molecule is one of the most
abundant in CRL 618 (with more than 150 lines in that survey). Maps of a few of the trace species — the first images obtained for most
of these — reveal diverse angular distributions, allowing us to distinguish the different regions in which each species is present
in this complex source.

Facilitator
-Name: Pei-Ying Hsieh

===============June 14 Fri==============

キャンパス：三鷹
セミナー名：ATCセミナー
定例・臨時の別：臨時
日時：6月14日（金曜日）13時30分～14時30分
場所：大セミナー室 + Zoom

講演者： Pradip Gatkine 氏
所属： UCLA
タイトル：Astronomical instruments on a chip – Getting ready for the next-generation telescopes

Abstract：
Astrophotonics is the application of versatile photonic technologies to channel, manipulate, and disperse guided light from one or more telescopes to achieve scientific objectives in astronomy in an efficient and cost-effective way. The photonic platform of guided light in fibers and waveguides has opened the doors to next-generation instrumentation for both ground- and space-based telescopes in optical and near/mid-IR bands, particularly for the large and extremely large telescopes (ELTs). Utilizing the photonic advantage for astronomical spectroscopy is a promising approach to massively miniaturize the next generation of spectrometers for large ground- and space-based telescopes. In this talk, I will discuss some of the recent results from our efforts to design and fabricate high-throughput on-chip spectrometers based on Arrayed Waveguide Gratings (AWG). These devices are ideally suited for capturing the AO-corrected light and enabling exciting science cases, such as measuring exoplanet masses and characterizing exoplanet atmospheres. I will also discuss specific approaches to make this technology science-ready for the ELT era.

世話人の連絡先
-名前：永井　誠

備考：英語での講演。

===============June 14 Fri===============

Campus：Mitaka
Seminar：NAOJ Seminar
Regularly Scheduled/Sporadic：Regular
Date and time：June 14, 2024 15:30-16:30
Place：Zoom/Large Seminar Room (hybrid)

Speaker：Dr. Nimesh Patel
Affiliation：Center for Astrophysics/ Harvard University

Title：Building the Next Generation Event Horizon Telescope

Abstract:The next-generation Event Horizon Telescope (ngEHT) will be a transformative upgrade to the EHT, that will allow us to create time-lapse movies of supermassive black holes (SMBHs) at event horizon scales. By enhancing the angular resolution, dynamic range, and improved temporal coverage, the ngEHT promises a new era of discovery in black hole science, allowing us to study strong-field gravity features predicted by General Relativity (GR), active accretion, and relativistic jet launching processes. The ngEHT program aims to achieve these goals by adding four 10m-class submillimeter dishes at new geographic locations around the globe, for improved spatial frequency coverage. Several of the existing EHT stations will have upgraded receivers and fore-optics for simultaneous multifrequency observations (86, 230 and 345 GHz), and new backends and data recorders with significantly higher data rates (up to 320 Gb/s). The ngEHT will allow longer duration high cadence observations allowing creation of movies of black holes and jets. This talk will describe the ngEHT’s technical plans, design considerations, station siting, and the project’s timeline.

Facilitator
-Name：Takashi Moriya

=============== June 14 Fri===============

Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Sporadic
Date and time：14 June (Fri), 15:30-17:00
Place： Insei Seminar Room and Zoom

Speaker：Dr. Alexei Pevtsov
Affiliation：National Solar Observatory
Title： Integrated Synoptic Program at the US National Solar Observatory and ngGONG

Abstract：

Providing the background synoptic observations to characterize the variable solar activity and operating ground-based facilities to enable
such long-term observations are two key aspects of the US National Solar Observatory (NSO) mission, which are entrusted to NSO’s Integrated
Synoptic Program (NISP). The program operates two facilities: Global Oscillation Network Group (GONG) and Synoptic Optical Long‐term
Investigations of the Sun (SOLIS). Data from these facilities are provided to research and space weather operation communities. This talk
will overview the Program activities, provide status of GONG and SOLIS facilities, and discuss their future replacement – a ground-based
network of robotic instruments provisionally called next generation GONG (ngGONG).

Facilitator
-Name：Akiko Tei

Comment：Japanese (Slides will be in English)

2024.5.27-2024.6.2

May 28 Tue 15:00-16:00
Tea Talk
hybrid; Lecture Room and Zoom

May 29 Wed 14:30-15:30
ALMA-J seminar
hybrid; Room 102 in ALMA Building and Zoom

May 29 Wed 15:30-16:30
NAOJ Science Colloquium
hybrid; Large Seminar Room in Subaru Building and Zoom

詳細は下記からご覧ください。

=============== May 28 Tue===============

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：5/28（火）15：00～16：00
場所：講義室＋Zoom
講演者：縣　秀彦、花山　秀和、大越　治
所属：天文情報センター
タイトル：大越治「メキシコ・マサトラン　雲を通した日食」
　花山秀和「日食遠征報告～サンサバ編～」
　縣秀彦「日食遠征報告～ダラス編～」
　（3名それぞれ10分程度のトークの後、総合討論）
世話人の連絡先：
-名前：藤田登起子

備考：
参加方法：講義室＋Zoom

=============== May 29 Wed===============

Campus: Mitaka
Seminar: ALMA-J seminar
Date and time: 2024 May. 29 (Wed.), 14:30-15:30 JST
Place: Room 102 in ALMA building / Zoom (hybrid)
Speaker: Zongnan Li
Affiliation: NAOJ

Title: Ring or no ring – Revisiting the Multiphase Nuclear Environment in our Neighbor M31
Abstract:
Nuclear rings, prevalent in barred galaxies, offer great insights into the processes of gas transport toward galactic nuclei. However, our understanding of a peculiar nuclear ring, which has long been recognized to exist in our neighbor galaxy M31, remains elusive. Here we present a comprehensive study of this multi-phase gas structure, originally revealed by its dust emission, based on newly acquired mapping of CO(1-0) and CO(3-2) lines and archival spectroscopic imaging of atomic hydrogen and warm ionized gas, along with custom numerical simulations. These multi-wavelength data together provide an unprecedented view of the surface mass density distribution and kinematics of the nuclear ring, which challenges it being a single coherent structure. In particular, the ring is found to display a significant asymmetry in its azimuthal mass distribution, with the neutral gas concentrated in the northwestern segment while the ionized gas prominent in the southeastern segment. The observed off-centered and lopsided morphology disfavors an interpretation of gas streamers or resonance driven solely by a barred potential known to exist in M31. In addition, the ring’s line-of-sight velocity distribution suggests a circular motion with the assumed planar ring inclined by ∼ 30◦ relative to the outer disk of M31, which implies an external torque probably induced by the recent close-in passage of M32. Our hydrodynamical simulations tracking the evolution of nuclear gas of M31 influenced by both a barred potential and an oblique collision of M32, reveal the natural formation of asymmetric spiral arms several hundred Myr after the collision, which may mimic a ring-like feature under appropriate viewing angles. Therefore, we suggest that M31’s nuclear gas structure, instead of being a genuine rotating ring, comprises transient, asymmetric spirals with a substantial tilt.

Facilitator
-Name: Yu Cheng

===============May 29 Wed==============

Campus: Mitaka
Seminar: NAOJ Science Colloquium
Date and time: 2024 May 29 (Wed.), 15:30-16:30 JST
Place: the large seminar room / Zoom (hybrid)

Speaker: Pete Kuzma
Affiliation: NAOJ (as a JSPS International Fellow)
Title: Extended Structure in Globular Clusters
Abstract:
Globular star clusters (GCs) are significant building blocks of the Milky Way’s (MW) Galactic halo. With typical ages of approximately 10 billion years, GCs are relics from the earliest stages of galaxy formation and are suggested to have contributed significantly to the halo assembly process. The current population of over 160 GCs may represent a mere fraction of the initial population of GCs, as the halo is rich in stars with chemical abundances suggesting they originate from GCs. An exciting development over the past 20 years has been the discovery that several MW GCs possess significantly extended structures, sometimes reaching out to a few hundred parsecs (corresponding to many half-mass radii). The types of features found range from axisymmetric tidal tails to large diffuse stellar envelopes. Such structures are indicative of mass loss, but our understanding of extended stellar structures, such as chemistry, kinematics and overall ubiquity, is currently incomplete apart from a very small sample. This is primed to change as upcoming large spectroscopic surveys commence and provide spatial coverage and depth that have been difficult to achieve until now. In this talk, I will explore the nature of extended GC structures and their role in the build-up of the Milky Way halo. I will explore before and after the Gaia revolution, both chemically and kinematically, and how future surveys will revolutionise our view of GCs and their peripheries.

Facilitator
-Name: Kazumasa Ohno
Comment: English

2024.5.20-2024.5.26

May 21 Tue 10:00-11:30
太陽系小天体セミナー (Solar System Minor Body Seminar)
Zoom

May 22 Wed 10:30-12:00
SOKENDAI Colloquium
hybrid; Large Seminar Room in Subaru Building and Zoom

May 22 Wed 14:30-15:30
ALMA-J seminar
hybrid; Room 102 in ALMA Building and Zoom

May 22 Wed 15:30-16:30
NAOJ Science Colloquium
hybrid; Large Seminar Room in Subaru Building and Zoom

May 24 Fri 15:30-16:30
NAOJ Seminar
hybrid; Large Seminar Room in Subaru Building and Zoom

詳細は下記からご覧ください。

=============== May 21 Tue===============

キャンパス：三鷹
セミナー名：太陽系小天体セミナー (Solar System Minor Body Seminar)
定例・臨時の別：定例
日時：　5月　21日（火曜日）10時00分～11時30分
場所：zoom
講演者：長谷川均
タイトル: 研究紹介　

世話人の連絡先
-名前：渡部潤一
備考：zoomでの参加

=============== May 22 Wed===============

Campus：Mitaka
Seminar：SOKENDAI Colloquium
Regularly Scheduled/Sporadic：Scheduled
Date and time：May 22, 2024 10:30-12:00
Place：Large Seminar Room in Subaru Building and Zoom

Speaker：Miho Tan
Affiliation：SOKENDAI 2nd year (M2) (Supervisor: Mami Machida, Tomoya Takiwaki, Kazunari Iwasaki)
Title：Effect of companion star wind in the jet propagation from X-ray binary

Speaker：Kiyoaki Doi
Affiliation： SOKENDAI 5th year (D3) (Supervisor: Akimasa Kataoka, Hideko Nomura, Misato Fukagawa)
Title：ALMA Band 3 observations of the protoplanetary disk around PDS 70

Facilitator
-Name：Yoshiaki Sato
Comment：Language: English

===============May 22 Wed==============

Campus: Mitaka
Seminar: ALMA-J seminar
Date and time: 2024 May. 22 (Wed.), 14:30-15:30 JST
Place: Room 102 in ALMA building / Zoom (hybrid)
Speaker: Yumi Watanabe
Affiliation: Fukushima Univ. /NAOJ

Title: Elucidation of anomalies in the HCN(J=1-0)/CO(J=1-0) intensity ratio using nearby Seyfert galaxy

Abstract:
Galaxies and black holes co-evolve. To understand co-evolution, it is necessary to clarify the phenomenon of AGN. To clarify galaxy evolution, we focused on AGN. The phenomenon of AGN can affect the properties of molecular gases, which is why we are studying molecular gases.
HCN(1-0), which traces dense gas, has been used in investigating the physics of AGN.
We focused our study on NGC 1068, a nearby Seyfert galaxy(distance of about 14 Mpc). This galaxy has an AGN and is considered to have a typical stellar mass. It also has a circumnuclear disk (CND) of gas (radius ~0.2 kpc) surrounding the AGN. Therefore, we focused on this galaxy.
In addition to our group’s own data, we collected and synthesized archived data from ALMA telescopes around the world and used high-quality data to observe HCN and CO in NGC 1068. The HCN/CO intensity ratio was created and a maximum value of 1.09 was obtained. This value is unusually higher than the galaxy’s typical value of 0.1. The cause may be abnormal abundance or excitation. We will discuss the cause of the unusually high HCN/CO intensity ratios observed around the CND.

Facilitator
-Name: Yu Cheng

===============May 22 Wed==============

Campus: Mitaka
Seminar: NAOJ Science Colloquium
Date and time: 2024 May 22 (Wed.), 15:30-16:30 JST
Place: the large seminar room / Zoom (hybrid)

Speaker: Arnab Chaudhuri
Affiliation: NAOJ (JSPS)
Title: Excursion beyond the Standard Model Physics- Gravitational Waves and Beyond
Abstract:
The standard model of particle physics, even though very successful, however is incomplete. It fails to explain the origin of the matter-antimatter asymmetry, neutrino masses and have any suitable candidates for dark matter. Within the framework of the standard model electroweak phase transition is crossover in nature. Hence a lot of beyond the standard model theories have been established in both particle physics and cosmology to overcome these shortcomings. The recent results from NANOGrav have also established the existence of secondary or stochastic gravitational waves. In this talk, I will go through some models with the main focus being the creation of these stochastic gravitational waves due to a first order phase transition.

This talk will be primarily based on JCAP 01 (2018) 032, Phys.Rev.D
106 (2022) 9, 095016 and arXiv: 2404.10288 .

Facilitator
-Name: Hiroki Nagakura
Comment: English

===============May 24 Fri==============

Campus：Mitaka
Seminar：NAOJ Seminar
Regularly Scheduled/Sporadic：Regular
Date and time：May 24, 2024 15:30-16:30
Place：Zoom/Large Seminar Room (hybrid)

Speaker：Prof. Tom Millar
Affiliation：Queen’s University Belfast

Title： Gas-phase Astrochemistry: Successes and Challenges

Abstract: The importance of astrochemistry in elucidating physical conditions and processes in astronomy has grown remarkably in recent years in response to the development of novel instruments and observational facilities. As a result, astrochemical techniques are applied to a wide range of astronomical objects, from the solar system to star birth and death, to exoplanet atmospheres, to galaxies and even to the early evolution of the universe. In this talk, I will give a brief history of the development of the subject from its conception around 1950 to its birth, eventually induced by radio astronomy, in 1973.

The importance of astrochemistry as an essentially interdisciplinary discipline will be stressed given the need for gas-phase reaction rate coefficients over a wide temperature range as well as chemistry in and on icy grain mantles. I will introduce the new release of the UMIST Database for Astrochemistry (UDfA) that reflects the additional chemistry needed to model the 100 or so new molecules detected in the last decade.

I will also describe some results from the ATOMIUM project, an ALMA Large Program, aimed at understanding dust formation around O-rich AGB stars. A surprise finding is that all targets have density distributions that appear to be driven by the presence of a binary companion. ATOMIUM results, and ALMA observations of ‘unexpected’ complex molecules at a few stellar radii in the C-rich star IRC+10216, have shown the importance of UV photons from binary companions in determining the chemistry of their inner winds. I will discuss some attempts to explain these results and will finish with some challenges for the future development of the subject.

Facilitator
-Name：Takuma Izumi