Discovery of a new Wolf-Rayet star and a candidate star cluster in the Large Magellanic Cloud with Spitzer
Discovery of a new Wolf-Rayet star and a candidate star cluster in the Large Magellanic Cloud with Spitzer
复制标题
斯皮策在大麦哲伦星云中发现了一颗新的沃尔夫-拉叶星和一个候选星团
DOI：
10.1093/mnras/stu909
复制
发表时间：
2014
影响因子：
4.8
通讯作者：
R. A. Gruendl
中科院分区：
文献类型：
--
作者：
V. V. Gvaramadze;A.-N. Chené;A. Y. Kniazev;O. Schnurr;T. Shenar;A. Sander;R. Hainich;N. Langer;W.-R. Hamann;Y.-H. Chu;R. A. Gruendl
我们报道了通过斯皮策太空望远镜探测到的圆形外壳，首次在大麦哲伦星云中发现了一颗Wolf-Rayet(WR)恒星。对南双子座的后续观测将贝壳的中央恒星分解成两个部分，通过≈2弧秒(或≈0.5PC投影)彼此分开。其中一个成分是一颗带有H的WN3星，他的发射和吸收都是直线(我们使用了基于扩展Breysacher等人的编号系统将其命名为BAT99-3a)。目录)。第二组分的光谱分析表明，它是一颗B0-V星。随后用杜邦2.5米望远镜和南部非洲大望远镜对BAT99-3a进行的光谱观测表明，它是一个封闭的偏心双星系统，吸收线与一颗O伴星有关。我们使用非LTE波茨坦WR(POWR)代码分析了双星系统的光谱，确认WR分量是一颗非常热的(≈90kK)WN星。对于这颗恒星，我们推导出其光度为logL/Lȯ=5.45，质量损失率为10−5.8Mȯyr−1，发现恒星风的组成主要是氦，氢含量为20%。贝壳的光谱显示，有一个以BAT99-3a为中心的黑区，具有与贝壳相同的角半径(≈15角秒)。因此，我们为一类罕见的被WR星光电离的高激发星云增加了一个新的例子。对星云光谱的分析表明，贝壳是由未经处理的物质组成的，这意味着贝壳是从局部星际介质中卷起的。我们讨论了新发现的大质量恒星与它们可能成为以前未被发现的星团的成员之间的物理关系。
We report the first-ever discovery of a Wolf–Rayet (WR) star in the Large Magellanic Cloud via detection of a circular shell with theSpitzer Space Telescope. Follow-up observations with Gemini-South resolved the central star of the shell into two components separated from each other by ≈2 arcsec (or ≈0.5 pc in projection). One of these components turns out to be a WN3 star with H and He lines both in emission and absorption (we named it BAT99 3a using the numbering system based on extending the Breysacher et al. catalogue). Spectroscopy of the second component showed that it is a B0 V star. Subsequent spectroscopic observations of BAT99 3a with the du Pont 2.5-m telescope and the Southern African Large Telescope revealed that it is a close, eccentric binary system, and that the absorption lines are associated with an O companion star. We analysed the spectrum of the binary system using the non-LTE Potsdam WR (powr) code, confirming that the WR component is a very hot (≈90 kK) WN star. For this star, we derived a luminosity of logL/ Lȯ= 5.45 and a mass-loss rate of 10− 5.8Mȯyr− 1, and found that the stellar wind composition is dominated by helium with 20 per cent of hydrogen. Spectroscopy of the shell revealed an Heiiiregion centred on BAT99 3a and having the same angular radius (≈15 arcsec) as the shell. We thereby add a new example to a rare class of high-excitation nebulae photoionized by WR stars. Analysis of the nebular spectrum showed that the shell is composed of unprocessed material, implying that the shell was swept-up from the local interstellar medium. We discuss the physical relationship between the newly identified massive stars and their possible membership of a previously unrecognized star cluster.