月別アーカイブ: 2018年6月

Disk Structures around the Class I Protostar L1489 IRS Revealed by ALMA / Dynamics of jets/outflows from high-mass young stellar objects revealed by KaVA and ALMA observations

[Speaker1]
SAI Jinshi, D1 at the University of Tokyo(Supervisor: OHASHI Nagayoshi,,)

[Title]
Disk Structures around the Class I Protostar L1489 IRS Revealed by ALMA

[Abstract ]
We observed a Class I protostar, L1489 IRS with ALMA at high spatial resolutions of ~0.3” in ALMA Band 6 (230 GHz). Our new observations in C18O 2-1 emission allowed us to confirm that the Keplerian disk extends to ~600 au in radius. We also found a gap structure at a radius ~200-300 au on a disk in C18O 2-1, and that the gas disk of L1489 IRS consists of two disks, an inner disk extending to ~200 au and an outer disk extending to ~300-600 au in radius. Furthermore, it was found that the inner disk and outer disk are misaligned by ~15 deg by comparison between observations and a kinematic model of a Keplerian disk. This misaligned disk system suggests that the axis of angular momentum of an accretion changes its direction during the star and circumstellar disk formation process. 1.3 mm dust continuum extends to ~ 370 au continuously however a gap structure is seen in C18O. It infers that the gap in C18O is due to CO depletion but the origin of the C18O gas gap is still on debated.

[Speaker2]
Jungha Kim, SOKENDAI 4th year (D2)(Supervisor: Mareki Honma,Tomoya Hirota,Katsunori Shibata)
[Title]
Dynamics of jets/outflows from high-mass young stellar objects revealed by KaVA and ALMA observations

The first chemo-dynamical view of very metal-poor stars / Lyman alpha imaging around a hyperluminous QSO at z=2.84 with HSC

[Speaker1]
Tadafumi Matsuno, SOKENDAI 4th year (D2)(Supervisor: Wako Aoki,Yutaka Komiyama,Takuji Tsujimoto)

[Title]
The first chemo-dynamical view of very metal-poor stars

[Abstract]
The second data release of Gaia (Gaia DR2) enables us to explore motions of a large number of stars in the Milky Way. Maximum scientific output would be obtained by complimenting the Gaia data set with stellar chemical abundances, since stellar motions tell us about past dynamical interactions between Milky Way and satellite galaxies whereas chemical abundances tell us about past star formation activities. To understand the formation history of the Galactic stellar halo, one of the oldest structures in the Milky Way, we have crossmatched the SAGA database, which complies results of abundance measurements for very metal-poor stars in literatures, to the Gaia DR2 catalog. In this talk, after describing the procedure of the crossmatch, I will introduce the latest results from the first chemo-dynamical analysis of very metal-poor stars.

[Speaker2]
Satoshi Kikuta, SOKENDAI 4th year (D2)(Supervisor: Masa Imanishi,Yuichi Matsuda,Yutaka Komiyama)

[Title]
Lyman alpha imaging around a hyperluminous QSO at z=2.84 with HSC

[Abstract]
We present the results of our Lyα imaging around a hyperluminous QSO, HS1549+1919, at z=2.84 with Hyper Suprime-Cam (HSC). Thanks to the HSC’s overwhelmingly large FoV, we detected >3000 Lyα emitters (LAEs) in diverse environments within a 1.1 deg^2 FoV. The QSO is confirmed to reside in the very center of a protocluster and is surrounded by a ~1pMpc-scale diffuse Lyα nebula. The EW distribution and properties of Lyα halos are studied as a function of environments. At the center, extreme objects such as QSOs, LABs, and SMGs are far more abundant than fields, suggesting a large amount of gas is accreting towards the center.

Search for massive overdensities at z~2.2 with Subaru HSC / Wave-front error measurements and optical alignment of CLASP2 telescope

[Speaker1]
Yongming Liang, SOKENDAI 1st year (M1)(Supervisor: Nobunari Kashikawa (U.Tokyo),Masayuki Tanaka,Yuichi Matsuda)
[Title]
Search for massive overdensities at z~2.2 with Subaru HSC

[Speaker2]
Masaki Yoshida, SOKENDAI 4th year (D2)(Supervisor: Yoshinori Suematsu,Hirohisa Hara,Ryohko Ishikawa)
[Title]
Wave-front error measurements and optical alignment of CLASP2 telescope