Oct 18 Tue 10:00～11:30 太陽系小天体セミナー Zoom
Oct 19 Wed 10:30～12:00 SOKENDAI Colloquium Zoom
Oct 19 Wed 14:30～15:30 ALMA-J seminar Zoom
Oct 19 Wed 13:30～15:00 NAOJ Science Colloquium Zoom / Instrument Development Bldg. 3
詳細は以下をご覧ください。
10月18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：10月18日（火曜日）10時00分～11時30分
場所：zoom
講演者：土屋智恵
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
10月19日（水）
Campus：Mitaka
Seminar：SOKENDAI Colloquium
Regularly Scheduled/Sporadic：Regular
Date and time：October 19th, 2022 10:30-12:00
Place：Zoom
Speaker 1: Ko Hosokawa
Affiliation: SOKENDAI 4th year (D2) (Supervisor: Takayuki Kotani, Yusuke Minowa, Yuka Fujii)
Title: Exoplanet Atmosphere in the Glass: Measuring High-resolution Spectra of H2 Dominated Gas
Speaker 2: Chanoul Seo
Affiliation: SOKENDAI 4th year (D2) (Supervisor: Yuka Fujii, Masahiro Ikoma, Hideko Nomura)
Title: Review : A pebble accretion model for the formation of the terrestrial planets in the solar system
Facilitator
-Name：Matsuda, Graduate Student Affairs Unit
10月19日（水）
Campus：Mitaka,
Seminar：ALMA-J seminar
Regularly Scheduled/Sporadic： Every Wednesday
Date and time：19th October (Wed), 14:30 – 15:30
Place：Zoom
Speaker：Shota Notsu
Affiliation：RIKEN
Title：The molecular composition of shadowed proto-solar disk midplanes beyond the water snowline
Abstract：
Planets form and obtain their compositions in protoplanetary disks around young stars. The chemical compositions of gas and solid dust grains in these planet-forming disks will decide planetary compositions. The thermal structure in the protoplanetary disk plays an important role in controlling the disk chemical structure. The disk midplane temperature is potentially affected by the disk substructures such as dust traps/rings, which have been detected with recent ALMA observations. The dust depletion beyond the water snowline will cast a shadow (Ohno & Ueda 2021).
In our study (Notsu et al. 2022, ApJ, 936, 188), we adopted a detailed gas-grain chemical reaction network, and investigated the radial gas and ice abundance distributions of dominant carbon-, oxygen-, and nitrogen-bearing molecules in disks with shadow structures beyond the water snowline around a protosolar-like star. We also investigated the dependance of the disk chemical structures on ionisation rates and initial abundances.
In shadowed disks, the dust grains at r~3−8 au are predicted to have more than ~5−10 times amounts of ices of organic molecules such as H2CO, CH3OH, and NH2CHO, saturated hydrocarbon ices (such as CH4 and C2H6), in addition to H2O, CO, CO2, NH3, N2, and HCN ices, compared with those in non-shadowed disks which are composed mostly H2O, CO2, and NH3 ices. In the shadowed regions, we find that hydrogenation (especially of CO ice) is the dominant formation mechanism of complex organic molecules, rather than radical-radical reactions and gas-phase reactions. The gas-phase N/O ratios show much larger spatial variations than the gas-phase C/O ratios, and thus the N/O ratio is predicted to be a useful tracer of the shadowed region. N2H+ line emission is a potential tracer of the shadowed regions beyond the water snowline. We conclude that a shadowed region allows the recondensation of key volatiles onto dust grains, provides a region of chemical enrichment of ices that is much closer to the star than within a non-shadowed disk, and may explain to some degree the trapping of O2 ice in dust grains that formed comet 67P/Churyumov-Gerasimenko. We discuss that in the shadowed disks, Jupiter does not need to have migrated vast distances, and complex organic molecules can be formed in situ rather than being fully inherited from molecular clouds.
In this talk, first I will briefly review recent topics about astrochemistry in star and planet forming regions, and then present our recent modeling studies about molecular composition of shadowed disk midplanes (Notsu et al. 2022). We also discuss future prospects for molecular line observations of protoplanetary disks with much higher spatial resolutions (ALMA and ngVLA).
Notsu et al. 2022, ApJ, 936, 188: https://ui.adsabs.harvard.edu/abs/2022ApJ…936..188N/abstract
Facilitator
-Name：Masumi Shimojo, Yu Cheng
10月19日（水）
Campus：Mitaka
Seminar：NAOJ Science Colloquium
Regularly Scheduled/Sporadic：Every Wednesday
Date and time：2022 Oct. 19, 15:30-17:00
Place：zoom / Instrument Development Bldg. 3 (hybrid)
Speaker: Mitsuru KOKUBO
Affiliation：NAOJ
Title: AGN Variability: reverberation phenomena and variability-based AGN selection
Abstract: AGN accretion disk continua show temporal luminosity variations over the entire wavelength range from X-rays to optical on time scales of days to years.
The continuum variability induces the reverberation phenomena in the outer accretion disk, Broad Line Region (BLR), and dust torus IR emission.
The reverberation mapping technique has been used to put constraints on the radial extent and physical conditions of the otherwise unresolved accretion disk, BLR, and dust torus around the central supermassive black holes.
In this talk I will review the recent observational progress and emerging issues in the AGN reverberation mapping.
In the latter half of the talk, I will also discuss our ongoing work on the variability-based AGN survey with the Subaru/HSC time-domain data.
Facilitator
-Name：Akimasa Kataoka
Comment：English