M (sub)Dwarf Model Atmospheres: The Next Generation
M (sub)Dwarf Model Atmospheres: The Next Generation
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M（亚）矮星模型大气：下一代
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
P. Hauschildt
中科院分区：
文献类型：
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作者：
P. Hauschildt
本文综述了低温低质量恒星的分子和原子线覆盖对流模型大气的理论现状和研究现状。这些最新的模型适用于广泛的参数范围，包括已知最冷的M矮星、M次矮星和褐矮星候选者：4000k≥Teff≥1500k；5.5≥logg≥3.5；-4.0≤[M/H]≤+0.5。大气的特点是具有较厚的对流区，其光学深度低至τ ~ 10-3，并且具有近乎绝热的温度梯度。与传统的灰色大气模型不同，后一种特征导致光球中的局部温度远远超过Teff。合成光谱与M矮星的观测结果在从可见光到近红外的广泛光谱范围内非常吻合，但有一个明显的例外：与水波段的吻合。我们讨论了正在进行的将水不透明纳入冷恒星光谱的努力，以及与寻找褐矮星有关的模型的有趣结果。
We review the current theoretical situation and present state-of-the-art molecular and atomic line-blanketed convective model atmospheres of cool low-mass stars. These newest models are valid for a wide range of parameters encompassing the coolest known M dwarfs, M subdwarfs and brown dwarf candidates: 4000 K ≥ Teff ≥ 1500 K; 5.5 ≥ logg ≥ 3.5; and -4.0 ≤ [M/H] ≤ +0.5. The atmospheres are characterised by a thick convective zone reaching optical depths as low as τ ~ 10-3 and by a nearly adiabatic temperature gradient. This latter feature leads to local temperatures in the photosphere which far exceed Teff, unlike conventional grey atmosphere models. The synthetic spectra yield close agreement with observations of M dwarfs across a wide spectral range from the visual to the near-IR, with one notable exception: the fit to the water bands. We discuss ongoing efforts to incorporate water opacities in cool stellar spectra, as well as interesting results of the models relating to searches for brown dwarfs.