AI 中文总结
研究对八颗含碳冷白矮星进行多波长光谱大气建模，通过分析C2带等特征及不同光谱类型差异，结合碰撞诱导吸收等确定元素丰度，精确建模表征恒星，得到新密度数据，样本恒星质量与白矮星群体大致相符。
AI 中文摘要
这项工作对八颗富含碳大气的冷白矮星进行了多波长光谱的大气建模，其中 DQ 和 DQp 光谱类型各四颗。在所有六颗有波长小于 4000Å 数据的 DQ 星中检测到 C2 的德斯兰德 - 达赞布亚带。这些带在 DQp 类型中发生蓝移，与天鹅带观测一致，并能用相同压力畸变模型再现。样本中最冷的恒星显示出显著的近红外通量抑制，被确定为来自致密氦的碰撞诱导吸收，根据 CH 特征缺失估计[H/He]<-6。利用[H/He]=-6.8 的大气模型能正确再现 WD0038 - 226 的近紫外到近红外光谱能量分布，但 2μm 以上预测通量过高，无碳大气能很好再现中红外观测。多波长覆盖允许对这些恒星进行精确建模表征，包括约束流体氦中的电离平衡和由此产生的密度分布。本工作中发现的密度比以前研究确定的高 2 - 3 倍，最冷的恒星接近 2g/cm³。排除两颗最冷的 DQp 恒星获得的不确定高质量，样本恒星的质量与更广泛的白矮星群体大致一致，在 DQ - DQp 温度边界上没有差异。
英文摘要
This work presents atmospheric modeling of multi-wavelength spectra for eight cool white dwarfs with carbon-enriched atmospheres, with four each of spectral type DQ and DQp. The Deslanders-d'Azambuja bands of C2 are detected in all six DQ stars that have data covering wavelengths shorter than 4000A. These bands are blue shifted in the DQp types, consistent with that observed for the Swan bands, and reproduced with the same pressure distortion model. The coolest stars in the sample show significant near-infrared flux suppression, identified here as collision-induced absorption from dense helium, with trace hydrogen [H/He]<-6, estimated from the absence of CH features. Notably, the near-ultraviolet through near-infrared spectral energy distribution of WD0038-226 is correctly reproduced using an atmospheric model with [H/He]=-6.8; however, beyond 2um the predicted flux is too high, and a carbon-free atmosphere is able to reproduce the mid-infrared observations well. The multi-wavelength coverage permits accurate modeling characterization of these stars, including constraining the ionization equilibrium in fluid helium and the resulting density profiles. The densities found in this work are 2-3 times higher than determined in previous studies, approaching 2g/cm3 for the coolest stars. Excluding the uncertain high masses obtained for the two coolest DQp stars, the sample stars have masses that are broadly consistent with those found for the wider white dwarf population, with no difference across the DQ-DQp temperature boundary.
Comments10 pages, 6 figures, 2 tables, accepted to MNRAS
