Abundances in the Herbig Ae star HD 101412 - Abundance anomalies; λ Boo–Vega characteristics?
Abundances in the Herbig Ae star HD 101412 - Abundance anomalies; λ Boo–Vega characteristics?
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Herbig Ae 星 HD 101412 的丰度 - 丰度异常；λ Boo-Vega 特征？
DOI：
10.1051/0004-6361/201015361
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发表时间：
2010
影响因子：
6.5
通讯作者：
I. Savanov
中科院分区：
文献类型：
--
作者：
C. Cowley;S. Hubrig;J. F. Gonz'alez;I. Savanov
上下文最近的注意力已被导向非常年轻的恒星之间的丰度变化。目标。我们利用Herbig Ae星星HD 101412异常尖锐的光谱线，对它进行了详细的丰度研究。方法.测量高分辨率光谱以获得准确的波长和等效宽度。Balmer线拟合和电离平衡给出了Teff和log（g）之间的关系。异常异常和不确定的红化排除了使用光谱类型或光度法来固定Teff。激发温度用于打破Teff和log（g）之间的简并性。结果强谱线受到反常饱和的影响，这种反常饱和不能通过假定低微湍流来消除。通过将分析限制在弱（≤20 mA）线，我们发现中性和电离物质的一致结果，基于Teff = 8300 K和log（g）= 3.8的模型。光球层中的大多数难熔元素都已耗尽，而挥发物则是正常的，或者在氮的情况下，相对于太阳来说过剩。这些异常不同于Ap或Am星的异常。结论.我们认为，强谱线的异常饱和是由于从圆盘下落的物质加热了大气上层。总体丰度模式可能与在λ Boo星上发现的有关，尽管难熔元素的消耗更温和，更像织女星。然而，中间挥发性锌被耗尽，排除了一个简单的解释的丰富模式的气体颗粒分离。
Context. Recent attention has been directed to abundance variations among very young stars. Aims. We perform a detailed abundance study of the Herbig Ae star HD 101412, taking advantage of its unusually sharp spectral lines. Methods. High-resolution spectra are measured for accurate wavelengths and equivalent widths. Balmer-line fits and ionization equlibria give a relation between Teff, and log(g). Abundance anomalies and uncertain reddening preclude the use of spectral type or photometry to fix Teff. Excitation temperatures are used to break the degeneracy between Teff and log(g). Results. Strong lines are subject to an anomalous saturation that cannot be removed by assuming a low microturbulence. By restricting the analysis to weak (≤20 mA) lines, we find consistent results for neutral and ionized species, based on a model with Teff = 8300 K, and log(g) = 3.8. The photosphere is depleted in the most refractory elements, while volatiles are normal or, in the case of nitrogen, overabundant with respect to the sun. The anomalies are unlike those of Ap or Am stars. Conclusions. We suggest the anomalous saturation of strong lines arises from heating of the upper atmospheric layers by infalling material from a disk. The overall abundance pattern may be related to those found for the λ Boo stars, though the depletions of the refractory elements are milder, more like those of Vega. However, the intermediate volatile zinc is depleted, precluding a straightforward interpretation of the abundance pattern in terms of gas-grain separation.