Abstract

The asymmetry of the Fe I and Fe II lines in the solar flux spectra has been analyzed using three FTS atlases and the HARPS atlas; it was also analyzed in the spectra of 13 stars using observations on the HARPS spectrograph. Individual line bisectors of each star have been averaged to reduce observation noise. The obtained average bisectors in the stellar spectra are more or less similar to the C-shape well known for the Sun. In stars with rotation velocities greater than 5 km/s, the shape of the bisectors is closer to the slash symbol (/). The curvature and span of the bisectors increase with the temperature of the star. Our results confirm the known facts about the strong influence of rotation velocity on the span and shape of bisectors. The average convective velocity was determined based on the span of the average bisector, which shows the largest difference between the velocity of cold falling and hot rising convective flows of matter. It is equal to –420 m/s for the Sun as a star. In solar-type stars, it grows from –150 to –700 m/s with an effective temperature of 4800 to 6200 K, respectively. For the stars with greater surface gravity and greater metallicity, the average convective velocity decreases. It also decreases with star age and correlates with the velocity of micro- and macroturbulent movements. The results of the solar flux analysis showed that absolute wavelength scales in the FTS atlases coincide to approximately –10 m/s, except for the atlas of Hinkle et al., the scale of which is shifted and depends on the wavelength. In the range from 450 to 650 nm, the scale shift of this atlas varies from –100 to –330 m/s, respectively, and it equals –240 m/s on average. The resulting average star bisectors contain information about the fields of convective velocities and may be useful for hydrodynamic modeling of stellar atmospheres in order to study the characteristic features of surface convection.

中文翻译：

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太阳和太阳型恒星光谱中线的不对称性

摘要

使用三个FTS地图集和HARPS地图集分析了太阳辐射通量谱中Fe I和Fe II线的不对称性。还使用HARPS光谱仪对13颗恒星的光谱进行了分析。对每颗恒星的各个线平分线进行了平均，以减少观测噪声。恒星光谱中获得的平均等分线或多或少类似于太阳众所周知的C形。在自转速度大于5 km / s的恒星中，平分线的形状更接近于斜线符号（/）。等分线的曲率和跨度随恒星温度的升高而增加。我们的结果证实了有关旋转速度对等分线跨度和形状的强烈影响的已知事实。平均对流速度是根据平均等分线的跨度确定的，这显示了物质的冷对流和热对流的速度之间的最大差异。太阳作为恒星等于–420 m / s。在太阳型恒星中，它的速度从–150增至–700 m / s，有效温度分别为4800至6200K。对于具有更大表面重力和更大金属性的恒星，平均对流速度会降低。它也随着星龄的增加而减小，并且与微湍流和大湍流的运动速度相关。太阳通量分析的结果表明，除了Hinkle等人的图集（其范围会随波长变化而变化）之外，FTS图集中的绝对波长范围重合约为–10 m / s。在450至650 nm的范围内，该图集的比例偏移分别为–100至–330 m / s，平均等于–240 m / s。产生的平均星等分线包含有关对流速度场的信息，可能对恒星大气的流体动力学建模有用，以便研究表面对流的特征。