L-band spectroscopy of Galactic OB-stars
L-band spectroscopy of Galactic OB-stars
复制标题
银河 OB 星的 L 波段光谱
DOI：
10.1051/0004-6361/201016003
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发表时间：
2011
影响因子：
6.5
通讯作者：
J. Puls
中科院分区：
文献类型：
--
作者：
F. Najarro;M. Hanson;J. Puls
上下文通过辐射驱动的超音速风发生的质量损失是大质量恒星演化过程中的一个关键问题。两个突出的问题是目前的挑战理论的辐射驱动的风：风丛生和弱风问题。目标。我们试图获得准确的质量损失率OB星在不同的进化阶段，以限制我们目前的理解大规模星星风的影响，这两个问题。方法.我们通过大气代码cmfgen对十颗银河系OB星的样本进行了多波长定量分析，特别强调了L波段窗口。对Br α和Pf γ作为质量损失和凝聚诊断的潜力进行了详细的研究。结果对于具有密集风的物体，Br α采样中间风，而Pf γ映射内部风。结合其他指标（UV，H α，Br γ），这些线使我们能够限制风聚集结构，并获得“真正的”质量损失率。对于具有弱风的物体，Br α成为约束风的可靠诊断工具。叠加在相当浅的斯塔克吸收翼上的线多普勒核心处的发射分量对已经在非常低的λ值下的质量损失非常敏感。另一方面，线翼显示出与经典光学质量损失诊断H α相似的质量损失敏感性。结论.我们的研究揭示了巨大的诊断潜力的L -波段光谱得出的聚团性质和质量损失率的热星星风。我们相信Br α将成为以前所未有的精度测量非常低的质量损失率的主要诊断工具。
Context. Mass-loss, occurring through radiation driven supersonic winds, is a key issue throughout the evolution of massive stars. Two outstanding problems are currently challenging the theory of radiation-driven winds: wind clumping and the weak-wind problem . Aims. We seek to obtain accurate mass-loss rates of OB stars at different evolutionary stages to constrain the impact of both problems in our current understanding of massive star winds. Methods. We perform a multi-wavelength quantitative analysis of a sample of ten Galactic OB-stars by means of the atmospheric code cmfgen, with special emphasis on the L -band window. A detailed investigation is carried out on the potential of Br α and Pf γ as mass-loss and clumping diagnostics. Results. For objects with dense winds, Br α samples the intermediate wind while Pf γ maps the inner one. In combination with other indicators (UV, H α , Br γ ) these lines enable us to constrain the wind clumping structure and to obtain “true” mass-loss rates. For objects with weak winds, Br α emerges as a reliable diagnostic tool to constrain Ṁ . The emission component at the line Doppler-core superimposed on the rather shallow Stark absorption wings reacts very sensitively to mass loss already at very low Ṁ values. On the other hand, the line wings display similar sensitivity to mass loss as H α , the classical optical mass loss diagnostics. Conclusions. Our investigation reveals the great diagnostic potential of L -band spectroscopy to derive clumping properties and mass-loss rates of hot star winds. We are confident that Br α will become the primary diagnostic tool to measure very low mass-loss rates with unprecedented accuracy.