On the nature of WO stars: a quantitative analysis of the WO3 star DR1 in IC 1613 ?
On the nature of WO stars: a quantitative analysis of the WO3 star DR1 in IC 1613 ?
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关于 WO 星的性质：IC 1613 中 WO3 星 DR1 的定量分析？
DOI：
10.1051/0004-6361/201322155
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发表时间：
2013
影响因子：
6.5
通讯作者：
S. D. Mink
中科院分区：
文献类型：
--
作者：
F. Tramper;G. Gräfener;O. Hartoog;H. Sana;A. D. Koter;A. D. Koter;J. Vink;L. Ellerbroek;N. Langer;Miriam García;L. Kaper;S. D. Mink
上下文氧序沃尔夫-拉叶（WO）星被认为是最大质量恒星演化的最后阶段。特征性的强Ovi辐射可能来源于恒星风中氧丰度的增加。或者，Ovi辐射可能是由这些恒星的高温引起的，在这种情况下，WO星是更常见的碳序沃尔夫-拉叶星（WC）的高温延伸。目标。通过约束的物理性质和演化状态的DR 1，WO星星在低金属量的本星系群矮星系IC 1613和只有两个对象的同类中已知的SMC样金属量环境之一，我们的目标是调查WO星的性质和它们的演化与WC星的连接。方法.我们使用非本地的热力学平衡大气代码cmfgen模拟观测到的光谱的DR 1，并推导出其恒星和风参数。我们比较我们的价值观与其他研究WC和WO明星，以及与进化模型的预测。我们还使用光电离代码cloudy模拟了周围的星云。结果氧和碳的丰度，我们得到的值相比WC星。然而，它的温度和光度都比WC星高。DR1嵌入在本地组中已知最热的Hii区域中。以DR1为中心电离源的云模式能一致地再现星云的性质。结论. DR1的丰度和温度与核心氦燃烧模型的比较表明，DR1目前已进入氦燃烧的后半期。如果DR 1的性质代表WO类，这意味着WO星是WC星的高温和高光度延伸，并不一定代表更晚的演化阶段。
Context. Oxygen sequence Wolf-Rayet (WO) stars are thought to represent the final evolutionary stage of the most massive stars. The characteristic strong Ovi emission possibly originates from an enhanced oxygen abundance in the stellar wind. Alternatively, the Ovi emission can be caused by the high temperature of these stars, in which case the WO stars are the high-temperature extension of the more common carbon sequence Wolf-Rayet (WC) stars. Aims. By constraining the physical properties and evolutionary status of DR1, a WO star in the low-metallicity Local Group dwarf galaxy IC 1613 and one of only two objects of its class known in a SMC-like metallicity environment, we aim to investigate the nature of WO stars and their evolutionary connection with WC stars. Methods. We use the non-local thermodynamic equilibrium atmosphere code cmfgen to model the observed spectrum of DR1 and to derive its stellar and wind parameters. We compare our values with other studies of WC and WO stars, as well as with the predictions of evolutionary models. We also model the surrounding nebula using the photo-ionization code cloudy. Results. The oxygen and carbon abundances that we obtain are comparable to values found for WC stars. The temperature and luminosity are, however, higher than those of WC stars. DR1 is embedded in the hottest known Hii region in the Local Group. The nebular properties can be consistently reproduced by cloudy models adopting DR1 as central ionizing source. Conclusions. Comparison of the abundances and temperature of DR1 with core helium-burning models show that DR1 is currently well into the second half of helium burning. If the properties of DR1 are representative for the WO class, it would imply that WO stars are the high-temperature and high-luminosity extension of the WC stars, and do not necessarily represent a later evolutionary stage.
影响因子：
56.9
作者：
H. Sana;S. D. Mink;A. D. Koter;N. Langer;C. Evans;M. Gieles;E. Gosset;R. Izzard;J. L. Bouquin-J.
通讯作者：
H. Sana;S. D. Mink;A. D. Koter;N. Langer;C. Evans;M. Gieles;E. Gosset;R. Izzard;J. L. Bouquin-J.
银河系 WC 恒星光谱分析的恒星参数表明了新的演化序列
DOI：
10.1051/0004-6361/201117830
发表时间：
2012
期刊：
arXiv: Solar and Stellar Astrophysics
影响因子：
--
作者：
A. Sander;W.-R. Hamann;H. Todt
通讯作者：
H. Todt