【日時】4月18日(水) 10:30～12:00
【場所】国立天文台・三鷹 中央棟（北）1階 講義室
【発表者（敬称略）】（総研大 D2 坂井 伸行・三鷹、指導教員：本間 希樹
【タイトル】
Galactic Outer Rotation Curve project with VERA
【アブストラクト】
I will talk mainly about two topics,
(1) Sakai et al. 2012 in accepted and
(2) Future prospects of our project.
The abstract of (1) is shown as below：
We report measurement of trigonometric parallax of IRAS 05168+3634 with VERA.
The parallax is 0.532 +/- 0.053 mas, corresponding to a distance of 1.88+0.21 －0.17 kpc. This result is significantly smaller than the previous distance estimate of 6 kpc based on kinematic distance. This drastic change in the source distance revises not only physical parameters of IRAS 05168+3634, but also its location of the source, placing it in the Perseus arm rather than the Outer arm. We also measure proper motions of the source. A combination of the distance and the proper motions with systemic velocity
yields rotation velocity (Θ) of 227+9－11 km s－1 at the source, assuming Θ0 = 240 km s－1. Our result combined with previous VLBI results for six sources in the Perseus arm indicates that the sources rotate systematically slower than the Galactic rotation velocity at the LSR. In fact, we show observed disk peculiar motions averaged over the seven sources in the Perseus arm as (Umean, Vmean) = (11 +/- 3, -17 +/- 3) km s－1, indicating that these seven sources are systematically moving toward the Galactic center, and lag behind the Galactic rotation.

3月12日、三鷹キャンパスにて専攻修了式が執り行われました。
天文科学専攻としては今年が初めての開催です。
平成23年度修了生のうち4名が出席し、教員・在学生に盛大に見送られました。

続きを読む →

【日時】2月22日(水)　10:30～12:00
【場所】国立天文台・三鷹　中央棟（北）1階 講義室
【発表者（敬称略）】Sukom Amnart（総研大 D1・三鷹、指導教員 : 田村　元秀）
【タイトル】A Near-infrared Polarization Study of the BIP14 Bipolar Nebula
【アブストラクト】
We present new J(1.25um), H(1.63um) and Ks(2.15um) linear imaging polarimetric observations of bipolar nebula BIP14.
BIP 14 is excited by four stars of spectral types B0.5-A5 and has 3 lobes of nebulosity. The two bright lobes are bisected by a central dust lane (the dust disk) which is obviously identified in infrared observations. The polarization maps of two main lobes
show symmetric pattern about a single illuminating source in the main eastern lobe. The low polarization degrees of the main inner lobes (< 10 percent in J,H and Ks wavelengths) show this bipolar nebula is an combination of emission and reflection nebulosity . In addition, the position of trapezium stars in optical wavelengths, radio continuum observations and IRAS source are agreed with these infrared observations.

【日時】2月8日(水) 10:30～12:00
【場所】国立天文台・三鷹 中央棟（北）1階 講義室
【発表者（敬称略）】（総研大 Min Cheul Hong M2・三鷹、指導教員 : 本間 希樹）
【タイトル】
Orbit determination for R Aquarii
【アブストラクト】
R Aqr is one of the closest symbiotic systems and the only D-type system with radial velocity data suitable for orbital parameter estimation. The aims of our study are to determine reliable orbital parameters of R Aqr, and to establish connections between the orbital motion and other phenomena exhibited in this system.
R Aquarii (R Aqr) is a symbiotic system composed of a mass losing Mira long period variable and hot white dwarf companion which is believed to have an accretion disk. Interesting thing in this system is presence of a jet. A lot of orbital solutions were published, but came up with different results had wide range. Though observations of the system have not yielded consistent values of the orbital parameters, the binary parameters of the orbit determine whether or not Roche lobe outflow of the long period variable is a possibility or if interacting stellar winds are necessary to the jet and formation of accretion disk. Futermore, R Aqr is one of the only two symbiotics to have circumstellar masers asscoiated with the Mira so that VLBI observation gives us a great chance for studying symbiotic system beyond AGB stars.
In this presentation, we introduce the symbiotic system, R Aqr, expected orbital model from radial velocity data, and the VERA observation results so far achieved.