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基于 Gaia-DR3 与虚拟天文台的白矮星光谱型-温度分布

White dwarf spectral type-temperature distribution from Gaia-DR3 and the Virtual Observatory

S. Torres, P. Cruz, R. Murillo-Ojeda, F. M. Jiménez-Esteban, A. Rebassa-Mansergas, E. Solano, M. E. Camisassa, R. Raddi, J. Doliguez Le Lourec

备注：
7 pages, 11 pages. Accepted for publication in A&A
发表信息：
A&A 677, A159 (2023)
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AI总结：

研究利用 Gaia-DR3 低分辨率光谱和 J-PAS 窄带测光，对 500 pc 内白矮星进行 DA/非 DA 分类，并基于近 3.4 万颗无偏样本给出 5,500–40,000 K 的光谱型-温度分布。

摘要：

白矮星大气的表征对于准确推导恒星参数（如有效温度、质量和年龄）至关重要。我们旨在基于 Gaia 光谱，将距离在 500 pc 以内的白矮星群体分类为富氢大气或缺氢大气，并针对迄今最大的无偏观测样本，推导白矮星光谱型-温度随有效温度变化的准确分布。我们利用了最新可得的 Gaia 低分辨率光谱，这些光谱覆盖 500 pc 以内的 76,657 颗白矮星。我们计算了合成 J-PAS 窄带测光，并采用最新的富氢和富氦白矮星大气模型拟合了每个天体的光谱能量分布。我们估计了白矮星具有富氢大气的概率，并使用 Montreal White Dwarf Database（蒙特利尔白矮星数据库）验证了结果。最后，使用 La Plata 演化模型为每个天体推导了精确的有效温度值。我们已成功将总计 65,310 颗白矮星分类为 DA 型和非 DA 型，准确率为 94%。我们构建了一个包含近 34,000 个天体的无偏子样本，并在考虑潜在选择效应的同时，由此计算出覆盖 5,500 至 40,000 K 有效温度范围的精确光谱分布。光谱演化的若干特征具有统计显著性，例如富氦恒星在 T_eff 约 35,000–40,000 K 以及 22,000 < T_eff < 25,000 K 范围内的数量亏缺；此外，非 DA 型恒星比例从 18,000 K 向 T_eff 约 7,000 K 逐渐增加，并在该处达到 41% 的最大值，随后在更冷温度下下降。这些发现将为已提出的光谱演化模型提供精确约束。

英文摘要：

The characterization of white dwarf atmospheres is crucial for accurately deriving stellar parameters such as effective temperature, mass, and age. We aim to classify the population of white dwarfs up to 500 pc into hydrogen-rich or hydrogen-deficient atmospheres based on Gaia spectra and to derive an accurate spectral type-temperature distribution of white dwarfs as a function of the effective temperature for the largest observed unbiased sample of these objects. We took advantage of the recent Gaia low-resolution spectra available for 76,657 white dwarfs up to 500 pc. We calculated synthetic J-PAS narrow-band photometry and fitted the spectral energy distribution of each object with up-to-date models for hydrogen-rich and helium-rich white dwarf atmospheres. We estimated the probability for a white dwarf to have a hydrogen-rich atmosphere and validated the results using the Montreal White Dwarf Database. Finally, precise effective temperature values were derived for each object using La Plata evolutionary models. We have successfully classified a total of 65,310 white into DAs and non-DAs with an accuracy of 94%. An unbiased subsample of nearly 34,000 objects was built, from which we computed a precise spectral distribution spanning an effective temperature range from 5,500 to 40,000 K, while accounting for potential selection effects. Some characteristic features of the spectral evolution, such as the deficit of helium-rich stars at T_eff $\approx$35,000-40,000 K and in the range 22,000 < T_eff < 25,000 K, as well as a gradual increase from 18,000K to T_eff $\approx$7,000K, where the non-DA stars percentage reaches its maximum of 41%, followed by a decrease for cooler temperatures, are statistically significant. These findings will provide precise constraints for the proposed models of spectral evolution.

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