WN6ha + O5 碰撞风双星 WR 25 的详细光谱研究
A Detailed Spectroscopic Study of the WN6ha + O5 Colliding-wind Binary WR 25
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中文总结 AI 辅助
研究 WR 25 双星系统，通过获取新光谱改进轨道解，确认 O 伴星并确定其与 WN 星的质量比等，证明 He II λ4859 线吸收成分来源，确定 WN 光谱型，通过分析得出近似物理参数，明确其所属天体家族。
中文摘要 AI 辅助
大质量恒星对宿主星系环境有重大影响，确定其物理参数有助于约束演化模型。WR 25 双星系统中占主导的氮序列沃尔夫 - 拉叶星特别受关注，其氢含量高且有额外吸收线，可能仍在主序或接近离开主序。我们获取了该系统新的高分辨率光谱，改进了 WN 分量运动的 SB1 轨道解，确认了 O 伴星并证明其与 WN 星引力束缚，给出首个 SB2 解及质量比 2.02 ± 0.36，确定伴星为 O5(f^+) 型主序或巨星，表明主序 WN 星至少 55 太阳质量，属于极少见的 WNLh 天体家族。还证明 WR 25 的 He II λ4859 线 P - Cygni 轮廓中的吸收成分主要来自 O 型伴星，为 WN 分量采用 WN6ha 光谱型，并通过 CMFGEN 分析得出近似物理参数。
英文摘要
Massive stars have a major impact on their environment in their host galaxy. Observational determinations of their physical parameters are required to better constrain evolutionary models. In this context, the binary system WR 25 whose dominant spectral type is that of a nitrogen sequence Wolf-Rayet star, is of particular interest. It exhibits the highest known hydrogen content among the Milky Way Wolf-Rayet stars, as well as additional absorption lines. It is most probably an object still on the main-sequence or close to leaving it. We acquired new high-resolution spectra of this extremely interesting object. We present an improved version of the SB1 orbital solution for the motion of the WN component. We confirm the detection of the previously reported probable O companion and definitively prove that it is indeed gravitationally bound to the WN star. A first SB2 solution is presented, and a mass-ratio WN/O of 2.02 +/- 0.36 is derived. Following a spectral disentangling procedure, we identify the companion as an O5(f^+) star belonging to either the main-sequence (V) or giant (III) luminosity classes. The spectral type of the companion, together with the above-mentioned mass ratio, points to a very massive primary WN star of at least 55 solar masses. This confirms that WR 25 belongs to the family of very massive WNLh objects, a very poorly populated class in the Milky Way. We demonstrate that the absorption component in the P-Cygni profile of the He II lambda 4859 line of WR 25 is mainly due to the O-type companion, and we propose to adopt a WN6ha spectral type for the WN component of the system. On the basis of the extracted disentangled spectra, we derive approximate physical parameters through a detailed CMFGEN analysis, given the difficulty in constraining both the extinction towards WR 25 and the definitive brightness ratio between the components.
