Nature of blackbody stars
Nature of blackbody stars
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DOI：
10.1051/0004-6361/201834032
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发表时间：
2019-03
影响因子：
6.5
通讯作者：
A. Serenelli;R. Rohrmann;M. Fukugita
中科院分区：
文献类型：
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作者：
A. Serenelli;R. Rohrmann;M. Fukugita
斯隆数字巡天中的17颗恒星，以前被确定为DC级白色矮星（WD），据报道显示光谱非常接近黑体辐射，波长范围从紫外到红外。由于光谱中没有谱线和其他细节，这些天体的表面重力以前没有得到很好的约束，它们的有效温度是通过使用纯氦大气模型拟合连续谱来确定的。我们计算了纯氦和H/He混合物的模型大气，并使用了盖亚DR 2的弛豫时间，这些弛豫时间适用于17颗选定恒星中的16颗，以分析它们的物理特性。我们发现，这些恒星的大气层很可能被−6 ≤ log（NH/NHe）≤ −5.4的微量氢污染。对于这16颗具有盖亚星系的恒星，我们计算出的平均恒星质量为0.606 ± 0.076 M <$，这代表了WDs的典型质量值和表面重力（7.8 < logg < 8.3）。
A selection of 17 stars in the Sloan Digital Sky Survey, previously identified as DC-class white dwarfs (WDs), has been reported to show spectra very close to blackbody radiation in the wavelength range from ultraviolet to infrared. Because of the absence of lines and other details in their spectra, the surface gravity of these objects has previously been poorly constrained, and their effective temperatures have been determined by fits to the continuum spectrum using pure helium atmosphere models. We computed model atmospheres with pure helium and H/He mixtures and used Gaia DR2 parallaxes that are available for 16 of the 17 selected stars to analyze their physical properties. We find that the atmospheres of the selected stars are very probably contaminated with a trace amount of hydrogen of −6 ≤ log(NH/NHe) ≤ −5.4. For the 16 stars with Gaia parallaxes, we calculate a mean stellar mass 0.606 ± 0.076 M⊙, which represents typical mass values and surface gravities (7.8 < logg < 8.3) for WDs.