Oct 23 Mon 14:30-15:30 ALMA-J seminar hybrid (ROOM102 in ALMA building and ZOOM)
Oct 24 Tue 10:00-11:30 太陽系小天体セミナー zoom
Oct 24 Tue 16:00-17:00 NAOJ Seminar zoom/ Large seminar room in Subaru Building
Oct 25 Wed 10:30-12:00 SOKENDAI Colloquium Large Seminar Room in Subaru Building and Zoom
Oct 25 Wed 14:30-15:30 ALMA-J seminar hybrid (Small seminar room in Subaru building and ZOOM)
Oct 25 Wed 15:30-16:30 NAOJ Science Colloquium The large seminar room / Zoom (hybrid)
詳細は以下をご覧下さい。
=============== October 23 Mon===============
Campus: Mitaka
Seminar: ALMA-J seminar
Date and time: Oct 23rd (Mon) 14:30-15:30
Place: hybrid (ROOM102 in ALMA building and ZOOM)
Speaker: Alfonso Trejo
Affiliation: UNAM
Title: The participation of Mexico in the ngVLA
Abstract:
The ngVLA, led by the National Radio Astronomy Observatory (NRAO), will be the largest radio interferometer ever built in the northern hemisphere. With more than 200 antennas distributed across the US, Canada, and Mexico, the array will reach spatial resolutions and sensitivities without precedents. The ngVLA will open a new window on the universe through ultra-sensitive imaging of spectral lines and continuum emission with milliarcsecond resolution.
We will discuss current work the Mexican community is doing for selecting the final MID sites in Mexico, simulations to characterise the array with its critical longest north-south baselines, enabled by the antennas in Mexico. Briefly, we will discuss the observatory designs that Mexico is leading: antenna base foundations, antenna site layouts, and antenna supporting buildings.
To finalize, I will outline the plans for national and international conferences and workshops, aimed at audiences from newcomers to advanced users.
In the last part of the talk, I will briefly introduce the Nearby Evolved Stars Survey (NESS) project that aims to study a volume-complete sample of mass-losing stars in the Solar neighbourhood. A summary of its main science objectives and how they are enabled by JCMT, APEX, NRO, and ALMA observations will be provided. In particular, we will focus on the ongoing ACA observations and some of its preliminary results. Finally, we discuss synergies with the current VLA and the future ngVLA, including astrometry studies.
Organizers: Gianni Cataldi , Hiroshi Nagai
=============== October 24 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24日（火曜日）10時00分～11時30分
場所：zoom
講演者：浦川聖太郎
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 24 Tue===============
Campus：Mitaka
Seminar：NAOJ Seminar
Date and time：Oct 24 Tue 16:00-17:00
Place：zoom/ Large seminar room in Subaru Building
Speaker：Dr,Roland Bacon
Affiliation：Observatoire de Lyon
Title：WST – The Wide Field Spectroscopic Telescope
Abstract：The WST project aim to study and built an innovative 10-m class wide-field spectroscopic survey telescope (WST) in the southern hemisphere with simultaneous operation of a large field-of-view (5 sq. degree) and high multiplex (20,000) multi-object spectrograph facility with both medium and high resolution modes (MOS), and a giant panoramic integral field spectrograph (IFS). The ambitious WST top-level requirements place it far ahead of existing and planned facilities. In just its first 5 years of operation, the MOS will target 250 million galaxies and 25 million stars at medium resolution + 2 million stars at high resolution, and 4 billion spectra with the IFS. WST will achieve transformative results in most areas of astrophysics. The combination of MOS and IFS spectroscopic surveys is one of the key aspects of the project. It is very attractive because of the high complementarity between the two approaches. I will detail this innovative point using the example of the MOS and MUSE surveys performed in the CFS region. The project aims to be the next major post-ELT project. It is supported by a large consortium of very experienced institutes plus ESO, representing 9 European countries and Australia.
Facilitator
-Name：Oouchi, Masami
=============== October 25 Wed===============
Campus：Mitaka
Seminar：SOKENDAI Colloquium
Regularly Scheduled/Sporadic：Regular
Date and time：October 25, 2023 10:30-12:00
Place：Large Seminar Room in Subaru Building and Zoom
Speaker: Ryota Ichimura
Affiliation: SOKENDAI 3rd year (D1) (Supervisor: Hideko Nomura, Akimasa Kataoka, Nanase Harada)
Title: Gas-Grain Model for Carbon Isotope Fractionation of COMs in Star-Forming Cores
Abstract:
Understanding the isotopic composition of ice molecules in star-forming cores is a powerful tool for investigating the origin of organic molecules in solar system objects. Recent high-resolution ALMA observations have measured the carbon isotopic ratios (12C/13C) of Complex Organic Molecules (COMs) in the Class 0 low-mass protostellar object IRAS 16293-2422B. The measured isotopic values are comparable to the average values in the local interstellar medium or show lower values, that is enriched in 13C. Several model calculations , observations, and laboratory experiments suggest that COMs are formed on the dust grain surface during star-formation. However, there are no model calculations of carbon isotope fractionations of COMs, and the origin of observed fractionations is not well understood.
In this study, we use a physical model of a star-forming core undergoing gravitational contraction, and performing chemical reaction network calculations considering three phases: the gas phase, the grain surface, and the ice mantle. And then we systematically investigate the carbon isotopic fractionations of COMs including formation of icy COMs prior to star formation and subsequent their sublimation into the gas phase following star formation.
Before the protostar formation, the 12C/13C ratios of icy small carbon species exhibit bimodal profile: the derivative species from CO are slightly enriched in 13C, while those succeeded from C and C+ are depleted in 13C owing to isotope exchange reactions. Icy COMs, originating from simpler species, also show this bimodality or deviation from it due to mixing. Sublimated COMs reflect the 12C/13C ratios of their icy counterparts. However, parts of COMs originate from radical and ionised species at higher temperature (T > 20 K), which change the 12C/13C ratios of the molecules from that of their ice in the prestellar phase. Eventually, in our base model COMs exhibit more fractionated rather than the observed value. The additional dust surface reactions involving atomic carbon having occurred at shorter timescales relative to isotope exchange reactions, lead to formation of COMs originated from less fractionated atomic carbon.
Consequently, additional C-atom reactions mitigate isotope fractionation, and roughly reproduces the non-fractionated observed values. Nonetheless, further investigation is necessary to reproduce the observed values more comprehensively.
Speaker: Tomohiro Yoshida
Affiliation: SOKENDAI 3rd year (D1) (Supervisor: Hideko Nomura, Misato Fukagawa, Akimasa Kataoka)
Title: The First Spatially-resolved Detection of 12CN/13CN in a Protoplanetary Disk and Evidence for Complex Carbon Isotope Fractionation
Facilitator
-Name：Matsuda, Graduate Student Affairs Unit
=============== October 25 Wed===============
Campus: Mitaka
Seminar: ALMA-J seminar
Date and time: Oct 25th (Wed) 14:30-15:30
Place: hybrid (Small seminar room in Subaru building and ZOOM)
Speaker: Yoshihide Yamato
Affiliation: University of Tokyo
Title: ALMA Observations of the Disk around the Young Bursting Star V883 Ori: Spatial Distributions and Chemistry of Complex Organic Molecules
Abstract:
Complex organic molecules (COMs), potential precursors of prebiotic molecules, are key to understanding the chemical evolution from the interstellar medium to planetary systems. However, the complex organic chemistry in protoplanetary disks, the immediate birthplace of planets, is still poorly understood. In this talk, I will present ALMA Band 3 observations of COMs in the disk around the young bursting star V883 Ori, which provides a unique opportunity to observe thermally sublimated COMs thanks to its warm nature. We detected ten oxygen-bearing COMs including 13C isotopologues in the disk. The radial distributions of the COM emission, revealed by detailed line profile analyses, show a common inner emission cavity, indicating that the COM emission may be hidden by the dust continuum emission due to the high temperature in the disk midplane caused by the viscous accretion heating. We also measured the abundance ratios of COMs with respect to CH3OH and the isotopic ratios (12C/13C and D/H) of COMs for the first time in a protoplanetary disk. The abundances of COMs are systematically higher than those in the warm protostellar envelopes of IRAS 16293-2422. The 12C/13C ratios of different COMs are consistently lower (~20-30) than the canonical ISM ratio (~69). The upper limits of the COM D/H ratios (< 0.01) are also lower than those in IRAS 16293-2422. These high COM abundances and peculiar isotopic ratios could be explained by the efficient formation of COMs from the 13C-enriched CO on the lukewarm dust grain surfaces. We will discuss the implications of these results for the chemical evolution of COMs in protoplanetary disks.
Organizers: Gianni Cataldi , Hiroshi Nagai
=============== October 25 Wed===============
Campus: Mitaka
Seminar: NAOJ Science Colloquium
Date and time: 2023 Oct. 25 (Wed.), 15:30-16:30
Place: The large seminar room / Zoom (hybrid)
Speaker: Haruka Kusakabe
Affiliation: NAOJ/JSPS
Title: CGM observations in emission
Abstract:
The evolution of galaxies is directly linked to the gas reservoirs surrounding them, so-called, “the circum-galactic medium (CGM)”. Gas and metals are exchanged via inflows and outflows through the CGM, which is an interface between the interstellar medium (i.e., galaxy) and intergalactic medium (the rest of the Universe). The CGM has been studied with absorption lines imprinted in spectra of bright background quasars (tomography), but this method is limited to line of sight and cannot provide the 2D spatial distribution of the CGM. Recent sensitive, wide-FoV integral-field spectrographs (such as VLT/MUSE and Keck/KCWI) make it possible to individually detect the CGM in emission, which allows us to map the gas and metals around host galaxies. In this talk, I will review the recent progress in observations and understanding of hydrogen gas and metals around z>~2 galaxies, which are detected as extended Lyα emission (Lyα haloes) and metal-line haloes. I will also connect the CGM observations in emission and absorption and introduce comparisons with simulations.
Facilitator
-Name: Hiroki Nagakura
Comment: English