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arXiv 1208.5486astro-ph.SR
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在小麦哲伦星云中发现新的、缺乏尘埃的B[e]超巨星

Discovery of New, Dust-Poor B[e] Supergiants in the Small Magellanic Cloud

A. S. Graus, J. B. Lamb, M. S. Oey

摘要:

本文介绍了在小麦哲伦星云(SMC)中发现的三颗新的B[e]超巨星(sgB[e]星)。这三颗恒星(R15、R38和R48)都是在我们对SMC进行的逃逸和孤立O型星光谱巡天(RIOTS 4)过程中识别出来的。这些恒星的光谱与先前已知的B[e]星非常相似,呈现出许多低电离的禁止和允许发射线,如[Fe II]和Fe II。此外,我们的恒星的光度log(L/L_sun)> 4,表明它们是超巨星。然而,我们发现较低的红外过量和较弱的禁止发射线比以前确定的B[e]超巨星。因此,我们的恒星看起来要么比其他sgB[e]星的拱星盘中的物质更少,要么拱星盘中的物质具有更低的尘埃含量。我们认为,这些可能构成一个新的子类的尘埃贫sgB[e]星。

英文摘要:

We present the discovery of three new B[e] supergiants (sgB[e] stars) in the Small Magellanic Cloud (SMC). All three stars (R15, R38, and R48) were identified in the course of our Runaways and Isolated O Type Star Spectroscopic Survey of the SMC (RIOTS4). The stars show optical spectra that closely resemble those of previously known B[e] stars, presenting numerous low-ionization forbidden and permitted emission lines such as [Fe II] and Fe II. Furthermore, our stars have luminosities of log(L/L_sun) > 4, demonstrating that they are supergiants. However, we find lower infrared excesses and weaker forbidden emission lines than for previously identified B[e] supergiants. Thus our stars appear to either have less material in their circumstellar disks than other sgB[e] stars, or the circumstellar material has lower dust content. We suggest that these may constitute a new subclass of dust-poor sgB[e] stars.

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