Demonstration of a Novel Method for Measuring Mass-loss Rates for Massive Stars
Demonstration of a Novel Method for Measuring Mass-loss Rates for Massive Stars
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测量大质量恒星质量损失率的新方法演示
DOI：
10.3847/1538-4357/aab3e0
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
M. Povich
中科院分区：
文献类型：
--
作者：
H. Kobulnicky;W. Chick;M. Povich
大质量恒星在恒星风中喷射质量的速度显著影响着它们的演化路径。宇宙的核合成速率、爆炸性恒星现象和致密天体的形成都取决于这一鲜为人知的恒星演化方面。我们采用一种未开发的观测技术来测量O星和早期b星的质量损失率。我们的方法没有可调参数，它利用了恒星风和周围星际介质之间的压力平衡原理，用于产生红外弓激波星云的高速恒星。20颗产生弓形激波的恒星的结果与O5-O9.5主序星的两组理论预测结果很好地吻合，得到= 1.3 × 10−6至2 × 10−9。虽然从这个样本中得到的值比理论期望的值小了大约两倍，但与标准的质量损失方法相比，这种差异大大减少了。弓形激波衍生的质量损失率比基于h α的测量值（未校正团块）小10倍，比基于紫外吸收谱线的P4+和其他诊断值大近一个数量级。形成一个显著的红外弓形激波星云似乎需要至少几厘米−3的周围星际密度。对早期b型恒星的测量还不令人信服，因为我们的样本数量少，而且在较低恒星亮度的情况下缺乏明确的理论预测。这些结果可能部分解决了现存的“弱风问题”。该技术有望确定弱风状态下的质量损失率。
The rate at which massive stars eject mass in stellar winds significantly influences their evolutionary path. Cosmic rates of nucleosynthesis, explosive stellar phenomena, and compact object genesis depend on this poorly known facet of stellar evolution. We employ an unexploited observational technique for measuring the mass-loss rates of O and early-B stars. Our approach, which has no adjustable parameters, uses the principle of pressure equilibrium between the stellar wind and the ambient interstellar medium for a high-velocity star generating an infrared bow shock nebula. Results for 20 bow-shock-generating stars show good agreement with two sets of theoretical predictions for O5–O9.5 main-sequence stars, yielding = 1.3 × 10−6 to 2 × 10−9 . Although values derived for this sample are smaller than theoretical expectations by a factor of about two, this discrepancy is greatly reduced compared to canonical mass-loss methods. Bow-shock-derived mass-loss rates are factors of 10 smaller than Hα-based measurements (uncorrected for clumping) for similar stellar types and are nearly an order of magnitude larger than P4+ and some other diagnostics based on UV absorption lines. Ambient interstellar densities of at least several cm−3 appear to be required for formation of a prominent infrared bow shock nebula. Measurements of for early-B stars are not yet compelling owing to the small number in our sample and the lack of clear theoretical predictions in the regime of lower stellar luminosities. These results may constitute a partial resolution of the extant “weak-wind problem” for late-O stars. The technique shows promise for determining mass-loss rates in the weak-wind regime.
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.
失控早期恒星弓形激波的多波长观测特征建模
影响因子：
4.8
作者：
Acreman D
通讯作者：
Acreman D