Spectroscopic and evolutionary analyses of the binary system AzV 14 outline paths toward the WR stage at low metallicity
Spectroscopic and evolutionary analyses of the binary system AzV 14 outline paths toward the WR stage at low metallicity
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双星系统 AzV 14 的光谱和演化分析概述了低金属丰度下通往 WR 阶段的路径
DOI：
10.1051/0004-6361/202345881
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发表时间：
2023
影响因子：
6.5
通讯作者：
Kehrig, C.
中科院分区：
文献类型：
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作者：
Pauli, D.;Oskinova, L. M.;Hamann, W.-R.;Bowman, D. M.;Todt, H.;Shenar, T.;Sander, A. A.;Erba, C.;Gómez-González, V. M.;Kehrig, C.
在低金属量星系中观测到的沃尔夫-拉叶（WR）恒星的起源，如小麦哲伦云（SMC），还没有被理解。标准的单星星演化模型预测WR星应该起源于非常大质量的O型星星祖先，但这些非常罕见。另一方面，双星演化模型预测WR星可能起源于近距离双星中的主星。目的我们对大质量O星星AzV 14进行分析，以光谱确定其基本参数和星风参数，然后用恒星演化模型研究从O型到WR阶段的演化路径。使用非局域热力学平衡（LTE）恒星大气程序PoWR分析了AzV 14的紫外和光学光谱。利用PHOEBE程序提取并分析了TESS光变曲线。结果AzV 14为密近双星系统，周期P = 3.7058 ± 0.0013d。 该联星由两颗相似的主序星组成，质量为M1，2≈ 32 M ⊙。 这两颗恒星都有微弱的恒星风，质量损失率为log/（M yr−1）= −7.7 ± 0.2。双星演化模型可以解释根据经验推导出的恒星和轨道参数，包括AzV 14组件在赫兹-罗素图上的位置，揭示了它目前的年龄为330万年。 该模型预测，主星将演变成一个WR星星，Teff为100 kK，而第二，这将吸积大量的质量在第一个质量转移阶段，将成为一个较冷的WR星星，Teff为50 kK。 此外，WR星的下降，从二元成分，已吸积大量的质量预测有增加的氧丰度相比，其他WR星。该模型的预测是支持的光谱分析的WR星星在SMC.ConclusionsInspired的二进制演化模型，我们假设，人口的WR星在低金属丰度星系可能有双峰温度分布。较热的WR星可能起源于主星，而较冷的WR星则是次级星的进化后代，如果它们吸积了大量的质量。这些结果可能对我们理解低金属丰度下大质量星星反馈和双星演化通道具有广泛的意义。
ContextThe origin of the observed population of Wolf-Rayet (WR) stars in low-metallicity galaxies, such as the Small Magellanic Cloud (SMC), is not yet understood. Standard, single-star evolutionary models predict that WR stars should stem from very massive O-type star progenitors, but these are very rare. On the other hand, binary evolutionary models predict that WR stars could originate from primary stars in close binaries.AimsWe conduct an analysis of the massive O star, AzV 14, to spectroscopically determine its fundamental and stellar wind parameters, which are then used to investigate evolutionary paths from the O-type to the WR stage with stellar evolutionary models.MethodsMulti-epoch UV and optical spectra of AzV 14 are analyzed using the non-local thermodynamic equilibrium (LTE) stellar atmosphere code PoWR. An optical TESS light curve was extracted and analyzed using the PHOEBE code. The obtained parameters are put into an evolutionary context, using the MESA code.ResultsAzV 14 is a close binary system with a period ofP= 3.7058 ± 0.0013 d. The binary consists of two similar main sequence stars with masses ofM1, 2≈ 32M⊙. Both stars have weak stellar winds with mass-loss rates of logṀ/(M⊙yr−1) = −7.7 ± 0.2. Binary evolutionary models can explain the empirically derived stellar and orbital parameters, including the position of the AzV 14 components on the Hertzsprung-Russell diagram, revealing its current age of 3.3 Myr. The model predicts that the primary will evolve into a WR star withTeff≈ 100 kK, while the secondary, which will accrete significant amounts of mass during the first mass transfer phase, will become a cooler WR star withTeff≈ 50 kK. Furthermore, WR stars that descend from binary components that have accreted significant amount of mass are predicted to have increased oxygen abundances compared to other WR stars. This model prediction is supported by a spectroscopic analysis of a WR star in the SMC.ConclusionsInspired by the binary evolutionary models, we hypothesize that the populations of WR stars in low-metallicity galaxies may have bimodal temperature distributions. Hotter WR stars might originate from primary stars, while cooler WR stars are the evolutionary descendants of the secondary stars if they accreted a significant amount of mass. These results may have wide-ranging implications for our understanding of massive star feedback and binary evolution channels at low metallicity.
微弱天体光谱仪
DOI：
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发表时间：
1975
期刊：
影响因子：
--
作者：
W. Devereux
通讯作者：
W. Devereux