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