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arXiv 1908.03025astro-ph.SRastro-ph.GA
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用Gaia DR2探测M矮星的光度-温度-半径关系

Exploring the M-dwarf Luminosity--Temperature--Radius Relationships using Gaia DR2

Sam Morrell, Tim Naylor

备注：
Accepted for publication in MNRAS 3 August 2019. 19 pages, 19 figures. Online supplementary material currently available at https://github.com/sammorrell/mn19-supplementary-material and https://doi.org/10.24378/exe.1683
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摘要：

越来越多的证据表明，与理论模型相比，M矮星遭受半径膨胀，这表明模型缺少一些关键的物理学，这些物理学需要完全描述有效温度$(T_{\rm SED})$小于4000 K的恒星。盖亚DR 2距离的出现最终使大型数据集可以确定这种影响的性质和程度。我们使用由$>$ 15，000颗恒星组成的全天空样本来确定亮度、温度和半径之间的经验关系。这是通过利用修改后的光谱能量分布拟合方法，仅使用几何距离和多波段光度学来完成的。与模型相比，我们测量的半径显示出$3 - 7\%$的膨胀，但不超过膨胀序列中的$1 - 2\%$内在扩散。我们表明，我们目前能够确定M-矮星半径的精度为$2.4\%$使用我们的方法。然而，我们确定，这是有限的金属丰度测量，这有助于$1.7\%$测量的半径散射的精度。我们还提出的证据表明，恒星磁性目前无法解释半径膨胀的M-矮星。

英文摘要：

There is growing evidence that M-dwarf stars suffer radius inflation when compared to theoretical models, suggesting that models are missing some key physics required to completely describe stars at effective temperatures $(T_{\rm SED})$ less than about 4000K. The advent of Gaia DR2 distances finally makes available large datasets to determine the nature and extent of this effect. We employ an all-sky sample, comprising of $>$15\,000 stars, to determine empirical relationships between luminosity, temperature and radius. This is accomplished using only geometric distances and multiwave-band photometry, by utilising a modified spectral energy distribution fitting method. The radii we measure show an inflation of $3 - 7\%$ compared to models, but no more than a $1 - 2\%$ intrinsic spread in the inflated sequence. We show that we are currently able to determine M-dwarf radii to an accuracy of $2.4\%$ using our method. However, we determine that this is limited by the precision of metallicity measurements, which contribute $1.7\%$ to the measured radius scatter. We also present evidence that stellar magnetism is currently unable to explain radius inflation in M-dwarfs.

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