Modeling of the outer atmosphere of cool stars based on the ISO spectroscopy

基于 ISO 光谱的冷恒星外层大气建模

• 批准号: 11640227
• 负责人: TSUJI Takeshi
• 金额: $ 2.24万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640227/
• 关键词: ISO; infrared spectra; red supergiants; red giants; brown dwarfs; Molecular Sphere; dust cloud; non-gray model photosphere; M型巨星; K型巨星; 褐色彗星; 非灰色大気モデル; 色-等級図11-43; 水分子; ダスト; M型矮星; 光球; 彩層; 恒星風; ISO(Infrared Space Observatory); 早期M型超巨星 /

1. From the analysis of ISO SWS spectra, supplemented with those from the ISO data archive, we show that water exists throughout red (super)giants including K giant a Tau (Aldebaran), early M supergiants a Ori (Betelgeuse) & μ, Cep, and all the M 'giants of MOIII - M9III Water was discovered in α Ori & μ Cep nearly 40 years ago by the pioneering space mission with Stratoscope II, but this important discovery was so unexpected at that time (and even today) that it has been misinterpreted and overlooked for a long time. We rediscovered this unexpected phenomenon and extended it to a larger sample of cool luminous stars. The excitation temperatures of the water bands are rather high (T_<ex> 【approximately equal】 1800K) and water appears in emission in μ, Cep as well as in late M giants. This finding is difficult to understand by the presently known models and/or theories on stellar atmospheres, and we propose instead the presence of a warm molecular sphere (MOLsphere) as the 4-th componen … More t of the stellar atmosphere consisting of the photosphere, chromosphere, and expanding cool wind. How to understand the origin of the MOLsphere and its physical structure should be a challenge to the theory of 'stellar atmosphere.2. We observed some spectra of M dwarfs by ISO, but we must wait for the next infrared missions such as Astro-F (ISAS) and SIKTF (NASA) to observe the spectra of brown dwarfs. To provide physical basis of interpreting the infrared spectra of cool dwarfs including M-type and brown dwarfe, we developed model photospheres of cool dwarfe, in which formation of dust cloud plays a crucial role. Based on a simple thermodynamical argument, we proposed unified cloudy model (UCM) in which dust can be sustained in the temperature range between the condensation temperature (T_<cond> 【approximately equal】 2000K) and the critical temperature・ (T_<cr> 【approximately equal】 1800K), independently of T_<eff>. Then, the dust cloud appears in the optically thin region in L dwarfe whose Teff are relatively high but will sink below the observable photosphere in the cooler T dwarfe. The observed CM diagram, SED, and spectra are well reproduced with our UCMs consistently throughout L to T dwarfe. This fact in turn can be regarded as an observational confirmation of our model of the cloud formation. We hope that our UCM will be of some clue for modeling the atmospheres of extrasolar giant planets. Less

1.通过对ISOSWS光谱的分析，并结合ISO数据库中的数据，我们发现水存在于包括K巨星aTau在内的红（超）巨星中（毕宿五），早期M超巨星a猎户座（参宿四）& μ，Cep，以及MOIII -M9 III水的所有M '巨星是近40年前由同温层二号的开创性太空使命在α Ori & μ Cep中发现的，但这一重大发现在当时（甚至在今天）都是如此出人意料，以至于长期以来一直被误解和忽视。我们重新发现了这一意想不到的现象，并将其扩展到更大的冷发光恒星样本。水带的激发温度很高（T_<ex>[约等于] 1800 K），在μ、Cep和晚M巨星中都有水的存在。这一发现很难用现有的恒星大气模型和理论来理解，我们提出了一个温暖的分子球（MOLsphere）作为第四组分的存在。 ...更多信息 恒星大气层的一部分，包括光球层、色球层和膨胀的冷空气。如何理解MOL层的起源及其物理结构，是对恒星大气理论的一个挑战。我们已经通过ISO观测到了M矮星的一些光谱，但是我们必须等待下一个红外任务，如Astro-F（ISAS）和SIKTF（NASA）来观测棕矮星的光谱。为了给解释冷矮星（包括M型和棕矮星）的红外光谱提供物理基础，我们发展了冷矮星的模型光球，其中尘埃云的形成起着至关重要的作用。本文从简单的物理论证出发，提出了统一的云模型（UCM），在该模型中，尘埃可以维持在凝结温度（T_<cond>[约等于] 2000 K）和临界温度（T_<cr>[约等于] 1800 K）之间，与T_[约等于]无关<eff>。然后，尘埃云出现在L矮星的光学薄区，其Teff相对较高，但在较冷的T矮星中将下沉到可观测光球之下。观测到的CM图、SED和光谱与我们的UCM在整个L到T矮星中一致地再现。这一事实反过来又可以被看作是对我们的云形成模型的观测证实。我们希望我们的UCM将为太阳系外巨行星的大气建模提供一些线索。少

项目成果

Tsuji, T.: "Water on the Early M Supergiant Stars α Orpomis and μ cephei"Astropys, J.. 538. L801-L807 (2000)

Tsuji, T.：“早期 M 超巨星 α Orpomis 和 μ cephei 上的水”Astropys, J.. 538. L801-L807 (2000)

Tsuji,T , ed. bu R. F. Wing: "Dust Formation in Stellar Photospheres : The Case of Carbon Stars from Dwarf to AGB , Proc. IAU Symp. The Carbon Star Phenomenon"Kluwer. 2000

辻，T，编辑。

T.Tsuji: "Dust formation in stellar photosphere"IAU Symp 177 Proceedings. 177. 313-324 (2000)

T.Tsuji：“恒星光球层中的尘埃形成”IAU Symp 177 会议记录。

T. Tsuji (T. Tsuji): "Warm dust in the cool brown dwarf Gliese22915 and spectroscopic diagnosis of dusty photospheres"Astrophysical Journal Letters. 520・2. L119-L122 (1999)

T. Tsuji（T. Tsuji）：“冷褐矮星 Gliese22915 中的温暖尘埃和尘埃光球层的光谱诊断”《天体物理学杂志快报》520・2（1999 年）。

T.Tsuji: "Waim molecular sphere avoina Ned swkergianrt stavs"Proc IAU Symposium 205. 205. 316-317 (2001)

T.Tsuji：“Waim molecular sphere avoina Ned swkergianrt stavs”Proc IAU Symposium 205. 205. 316-317 (2001)