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high spectral resolution observations with SOFIA/upGREAT
Abstract: The fine structure line of ionized carbon, [CII], at 158 μm is one of the strongest cooling lines of the dense interstellar medium. Located in the core region of the far-infrared spectral range, it is observable in the local universe only from space, balloon or airborne platforms, or at high redshifts in the ALMA bands, where it is used as tracer of star formation activity in early galaxies. The recent technological advances now allow routine highest spectral resolution heterodyne observations with the upGREAT instrument on board SOFIA, that resolve the [13CII] satellite lines with sufficient signal/noise, so that it is possible to measure directly the optical depth of the carbon fine structure line emission. We have performed such observations in seven sources ranging from simple to complex spatial and kinematic morphology. In all cases, we find clear evidence of significant optical depth. In many cases, the line profiles show clear evidence for foreground or self-absorption. The high column densities derived and, in many cases, the low temperatures of the foreground/self-absorption, are difficult to account for in standard model scenarios of photodissociation regions (PDRs). These findings imply, that one has to use with caution integrated line intensity ratios, when interpreting [CII] observations in the context of PDR models, to infer average properties of spectroscopically and spatially unresolved sources.
Language: English
Abstract: Substellar objects such as exoplanets and brown dwarfs rotate and some of them have detectable rapid rotation. Recently, rotation velocities of exoplanets have been detected and their rotation velocities are higher than those of planets in the Solar system. Rotation period of brown dwarfs also have been detected and some brown dwarfs have clearly rapid rotation. Their minimum rotation periods are only a few hours and rotation velocities are much higher than those of planets in the Solar system. If the substellar objects have rapid rotation, their shapes might be largely deformed due to the strong centrifugal forces. Their structures cannot be well described by spherical models and so non-spherical models are required to describe them. In order to consider their evolution and structures, an 1D spherical model clearly becomes invalid. At least a 2D model is required to consider the evolution and structures of such rapidly rotating substellar objects. Almost all evolutionary code for substellar evolution, however, can treat only 1D models and nobody has succeeded in obtaining rapidly rotating 2D evolutionary models consistently. As a first step toward the rapidly rotating 2D models, we calculated quasi-evolutionary sequences of rapidly rotating substellar objects using both 1D evolutionary calculation by MESA and 2D rapidly rotating equilibrium calculation by our new numerical scheme (Fujisawa 2015). As a result, we have found that some young rapidly rotating substellar objects are spinning up due to the gravitational contraction as they cool. They might exceed critical rotation and break-up rotation velocity within a few 100 Myrs if the angular momentum is conserved during the evolution. Such rapidly rotating substellar objects would loss their angular momentum by wind or flare to avoid brake-up and the angular momentum loss timescale should be of a few Myrs.
Language: English
東京大学・天文学教育研究センターでは2003年4月から, 院生コロキウムに引き続き, 談話会を開いています. 第一線で活躍されている研究者の方々を講師にお招きし, 最先端の研究成果をお話しいただきます. 講師の方には, 大学院生の参加者のことも考慮し, レビュー的な側面も含めた上で, ご自身の研究紹介をお願いしています.
| 13:30-14:30 | 院生コロキウム | 講義室 |
| 15:30-16:30 | 談話会 | 講義室 |
| 16:30- | お茶の時間 | 講義室横のお茶部屋~講師の方を交えて~ |
please replace _at_ to @
| # | Date | Speaker | Title | Chair |
| 313 | 2017/10/26 (Thu) 15:30 - 16:30 | Juergen Stutzki (Universitaet zu Koeln) | Optical depth of the Carbon 158 um line emission: high spectral resolution observations with SOFIA/upGREAT | KK |
| 314 | 2017/11/16 (Thu) 15:30 - 16:30 | 藤澤幸太郎 (早稲田大学) | Rapidly rotating substellar objects | MY |
| 315 | 2017/11/30 (Thu) 15:30 - 16:30 | 鈴木大介 (宇宙研 宇宙航空プロジェクト研究員) | 重力マイクロレンズ法を用いた系外惑星探査 | MY |
| 316 | 2017/12/07 (Thu) 15:30 - 16:30 | 小西美穂子 (NAOJ 特任研究員) | TBA | |
| 31X | 2017/12/21 (Thu) 15:30 - 16:30 | 大屋 瑶子 (東京大学物理学専攻) | TBA | KK |
詳細はこちら: 平成29 (2017) 年度談話会
| # | Date | Speaker | Title | Chair |
| 301 | 2017/4/13 (Thu) 15:30 - 16:30 | Tao WANG (IoA/U.Tokyo (4月から)) | New insights into the formation of the most massive galaxies at high redshifts | KK |
| 302 | 2017/4/20 (Thu) 15:30 - 16:30 | Matthew W. Johns (U. Arizona) | The Magellan Experience - Building a 6.5 Meter Optical/Infrared Telescope | TT |
| 303 | 2017/4/27 (Thu) 15:30 - 16:30 | 滝脇知也 (国立天文台 理論部) | 重力崩壊型超新星の爆発機構 | MY |
| 304 | 2017/5/11 (Thu) 15:30 - 16:30 | 樫山和己 (東京大学 物理学専攻) | A FRB in a bottle | MY |
| 305 | 2017/5/25 (Thu) 15:30 - 16:30 | 西村優里 (天文学教育研究センター (4月から)) | 低重元素量の矮小銀河における分子雲の化学組成 | KK |
| 306 | 2017/6/1 (Thu) 15:30 - 16:30 | 片岡章雅 (国立天文台フェロー) | Millimeter-wave polarization as a tool of investigating the planet formation | KK |
| 307 | 2017/6/15 (Thu) 15:30 - 16:30 | 端山和大 (東京大学 宇宙線研) | 重力波望遠鏡の現状と、検出から物理へ | MT |
| 308 | 2017/6/22 (Thu) 15:30 - 16:30 | 福島登志夫 (国立天文台) | 宇宙人存在問題 Question on Alien Civilization Existence | TT |
| 309 | 2017/7/13 (Thu) 15:30 - 16:30 | Ryan M. Lau (Caltech/JPL) | High Energy, Cool Transients: Investigating Infrared-Luminous Outbursts with Spitzer | KK |
| 310 | 2017/7/20 (Thu) 15:30 - 16:30 | 木坂将大 (青山学院大学) | 多波長観測で探るパルサー磁気圏構造 | MY |
| 311 | 2017/7/27 (Thu) 15:30 - 16:30 | 馬場彩 (東京大学 物理学専攻) | 超新星残骸のX線観測に関する最近の話題 | MY |
| 312 | 2017/10/12 (Thu) 15:30 - 16:30 | Jonathan Freundlich (Racah Institute of Physics, The Hebrew University) | Molecular gas reservoirs during the winding-down of star formation | MY |
