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从Gaia的天体测量和光度数据确定恒星和亚恒星双星的组件质量

Component masses in stellar and substellar binaries from Gaia astrometry and photometry

Max Planck Institute for Astronomy（马克斯·普朗克天文学研究所）

C. A. L. Bailer-Jones, L. Kreidberg

备注：
Accepted to A&A. Table 1 available from https://www.mpia.de/homes/calj
发表信息：
Astronomy & Astrophysics, 708, A249 (2026)
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AI总结：

利用Gaia的天体测量和光度数据，通过建立质量-流量关系，确定双星系统中恒星和亚恒星的个体质量，精度达10-20%。

摘要：

恒星和行星的质量可通过双星系统动态测量。对于未分辨的双星，时间序列天体测量提供了一些轨道参数，但无法确定组件质量，因为只能观测到系统的光中心运动。然而，由于恒星的光度与其质量相关，两个组件的光度观测提供了系统质量的信息。本文开发了一种方法，利用Gaia的天体测量轨道和三个波段的光度数据确定未分辨双星的组件质量。通过从恒星等时线模型中拟合的质量-流量关系，推断出未知的流量比。这使方法能够区分近等质量、近等亮度的恒星双星和星-行星双星，否则它们的天体测量特征相同。使用似然方法，我们在恒星参数上采样后验概率分布，通过年龄和金属度进行边缘化以获得个体质量。我们应用此方法于20000个主序星在太阳附近300 pc内的系统，使用Gaia数据释放3非单星目录的数据。主星质量的确定精度（一西格玛后验宽度）在90%的情况下为10-20%。次级质量，延伸到行星质量对象，精度较低，尽管一半的精度超过25%。有趣的是，添加红外光度或Gaia的光谱轨道对质量估计影响不大（分别小于4%和1%）。星际消光对这一样本影响也较小。这项工作表明，仅使用Gaia的天体测量和光度数据，无需大量后续工作，即可获得恒星和亚恒星对象的合理精确质量。

英文摘要：

The masses of stars and planets can be measured dynamically in binary systems. For an unresolved binary, time series astrometry yields some orbital parameters, but it cannot provide the component masses, because we observe only the motion of the system's photocentre. However, as a star's luminosity is related to its mass, the observable photometry of both components together provides information on the system mass. Here we develop a method to determine the individual component masses of an unresolved binary using the astrometric orbit together with three-band photometry from Gaia. We use a mass-flux relation fitted from stellar isochrone models for each Gaia band to infer the unknown flux ratio. This enables our method to distinguish between near equal-mass, near equal-brightness stellar binaries and star-planet binaries, which otherwise have identical astrometric signatures. Using a likelihood approach, we sample the posterior probability distribution over the stellar parameters, marginalizing over system age and metallicity to get the individual masses. We apply this to 20 000 systems with a main sequence primary within 300 pc of the Sun using data from the Gaia data release 3 non-single star catalogue. Primary masses can be determined with a precision (one-sigma posterior width) of 10-20% in 90% of cases. Secondary masses, which extend down to planetary-mass objects, are less precise, although half are more than 25% precise. Interestingly, adding either infrared photometry or spectroscopic orbits from Gaia does not change the mass estimates much (less than 4% and 1% respectively). Interstellar extinction likewise has little impact for this sample. This work shows that reasonably precise masses can be obtained for stars and substellar objects using just the Gaia astrometry and photometry without need for extensive follow-up.

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