【日時】5月16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１（敬称略）】片岡章雅（総研大 D1・三鷹、指導教員 : 富阪幸治)
【タイトル】
Settling Process of Dust Aggregates in Protoplanetary disks with Porosity Evolution
アブストラクト
abstract: How micron-sized dust aggregates evolve to kilo-meter-sized planetesimals in protoplanetary disks is one of the most important problems of the planet formation. Some previous studies using BPCA and/or BCCA models have shown that porosity has strong effects on coagulation and settling of dust aggregates. However, effects of the porosity evolution have not been taken into account before. We simulate coagulation of dust aggregates settling to an equatorial plane in a protoplanetary disk, using QBCCA model, in which the porosity evolution depends on the volume ratio of colliding two aggregates. We show that porous aggregates grow slowly and settle in longer timescale compared to compact grains. We also calculate wavelength-dependent optical depth and find that the 10 $\micron$ silicate feature remains in the case of porous aggregates even after they grow in the disk. Moreover, we find that compaction of dust aggregates affects optical depth in (sub)mm wavelength, which would be detected by ALMA.

【日時】5月2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1】利川潤　(総研大 D1、指導教員：柏川伸成)
【タイトル】Search for high-redshift protoclusters by wide-field imaging
【Abstract】
Galaxy clusters play an important role for the large-scale structure of the universe and galaxy evolution. Galaxy clusters are located in the densest peaks of dark matter, and galaxies lying inside galaxy clusters are generally more massive and older than those in low-density regions.
When and how were these distinct properties formed? One promising line of study is to investigate directly the primitive galaxy clusters, “protoclusters”, in the early universe. Especially, we focus on the start of cluster formation. However, only a few high-z protoclusters were found. Therefore, we are searching for new high-z protoclusters in the deep and wide field of Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) Deep fields, and found two protocluster candidates at z~6.
【発表者2】Pan Hsi-An (総研大 D1、指導教官：久野成夫)
【タイトル】Molecular gas and star formation properties of NGC 628
【Abstract】
It is widely accepted that molecular gas is the dominant material of star formation.
Since H2 (molecular hydrogen) is not observable, the second abundant molecular 12CO has become a proxy of tracing molecular gas. However, 12CO is optically thick, which is able to trace the molecular gas at the surface of molecular cloud only.
Therefore the observation in optically thin line, such as 13CO is needed. We observe both 12CO and 13CO toward NGC 628 to constrain the ability of a optically thin line in determining the molecular gas properties and its relation with star formation. Both observation and data analysis are ongoing.

【日時】4月25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１】Yoshifumi Ishizaki （総研大 D2・三鷹、指導教員 : Nobunari Kashikawa）
【タイトル】High-z QSO survey at z ~ 6 and 7 with Suprime-Cam
アブストラクト
We are on going deep zB/zR imagings for 7 deg^2 in total of UKIDSS-DXS fields in order to detect high-z QSOs around z ∼ 7 down to J<23.5. This observation is a new search for the most distant QSOs around z = 6 and 7 utilizing the unique capabilities of wide-field imaging of Subaru/Suprime-Cam, its high-sensitivity CCDs at 〜 1μm, and special filters to effectively isolate high-z QSOs from M/L/T dwarfs. I will speak about the unique way of observation mainly. 【発表者２】Keisuke Imase （総研大 D2・三鷹、指導教員 : Masatoshi Imanishi） 【タイトル】The new black hole mass estimator: Paα アブストラクト Active Galactic Nuclei (AGNs) are luminous objects, found in the centre of galaxies. It is believed that they have supermassive black hole and accretion disk in their central region, surrounded with broad-line region(BLR). This picture is called "Unified model for AGN" (e.g., Antonucci 1993) Today, the correlation between masses of black holes of AGNs (MBHs) and the properties of their host galaxies has been found (so-called "co-evolution"). Therefore, it is very important to estimate MBHs of more AGNs in more accurate way. MBHs are mainly estimated with broad optical and UV emission lines (Hβ, MgII), using their line width and flux. More than half of AGNs, however, are affected with the foreground gas and dust. For such AGNs (so-called "dusty AGNs"), it is difficult to use UV/optical lines as estimators of MBHs. On the other hand, Paα line, the strongest line in near-infrared(NIR) and free of blending, are detectable in "dusty AGNs" and ultra luminous IR galaxy(ULIRG). We have observed 21 nearby PG QSOs with IRTF/SpeX in order to establish Paα lines as a new estimator of MBHs for dusty AGNs. In the colloquium, we report the present results and our future work.

【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。

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