The Unexpected Spectrum of the Innermost Ejecta of the Red Hypergiant VY CMa
The Unexpected Spectrum of the Innermost Ejecta of the Red Hypergiant VY CMa
复制标题
红超巨星 VY CMa 最内部喷射物的意外光谱
DOI：
10.3847/2041-8213/ab11e5
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
W. Vlemmings
中科院分区：
文献类型：
--
作者：
R. Humphreys;L. Ziurys;J. Bernal;M. Gordon;L. Helton;K. Ishibashi;T. Jones;A. Richards;W. Vlemmings
哈勃太空望远镜/STIS对vycma中最靠近中心恒星的小团块和细丝的光谱显示，长期以来被认为形成于星周尘埃壳的非常强的K i发射和TiO和VO分子发射，实际上起源于距离恒星数百au的几个小团块。这些离我们最近的抛射物中的K线比恒星上的强10-20倍。观测结果也证实了VO是一种星周分子。在这封信中，我们讨论了特征的光谱，它们的运动和年龄，以及分子发射的识别。小团块中原子和分子特征的强度为激发过程提出了一个天体物理学问题。我们表明，这些团块必须对恒星的辐射有几乎清晰的视线。
Hubble Space Telescope/STIS spectra of the small clumps and filaments closest to the central star in VY CMa reveal that the very strong K i emission and TiO and VO molecular emission, long thought to form in a dusty circumstellar shell, actually originate in a few small clumps hundreds of au from the star. The K i lines are 10–20 times stronger in these nearest ejecta than on the star. The observations also confirm VO as a circumstellar molecule. In this Letter we discuss the spectra of the features, their motions and ages, and the identification of the molecular emission. The strength of the atomic and molecular features in the small clumps present an astrophysical problem for the excitation process. We show that the clumps must have a nearly clear line of sight to the star’s radiation.