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arXiv 2012.13791astro-ph.SR
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太阳和日型星光谱中的谱线不对称性

Asymmetry of Lines in the Spectra of the Sun and Solar-Type Stars

V. A. Sheminova

摘要:

我们用三个FTS图集和HARPS图集分析了太阳通量谱中Fe Ⅰ和Fe Ⅱ谱线的不对称性,并用HARPS摄谱仪的观测数据分析了13颗恒星的光谱。为了减少观测噪声,对每颗恒星的线平分线进行了平均。得到的恒星光谱的平均平分线或多或少类似于太阳所熟知的形状C。在自转速度大于5 km/s的恒星中,平分线的形状更像/。平分线的曲率和跨度随着恒星的温度而增加。我们的研究结果证实了已知的事实强烈影响的旋转速度的跨度和形状的平分线。平均对流速度是根据平均平分线的跨度确定的,它显示了物质的冷下降和热上升对流速度之间的最大差异。它等于太阳作为恒星时的-420米/秒。在太阳型恒星中,它的增长速度从-150到-700 m/s,有效温度分别为4800到6200 K。对于表面重力和金属量较大的恒星,平均对流速度降低。它还随着恒星年龄的增加而减少,并与微观和宏观湍流运动的速度相关。太阳通量分析结果表明,除Hinkle等图集外,所用FTS图集的绝对波长标度基本一致,精度约为-10 m/s,其尺度是变化的并且取决于波长。在450 ~ 650 nm范围内,该图谱的标度漂移分别为-100 ~-330 m/s,平均为-240 m/s。由此产生的平均恒星平分线包含对流速度场的信息,并可能是有用的恒星大气的流体动力学建模,以研究表面对流的特征。

英文摘要:

We have analysed the asymmetry of lines Fe I and Fe II in spectra of a solar flux using three FTS atlases and the HARPS atlas and also in spectra of 13 stars using observation data on the HARPS spectrograph. To reduce observation noise individual line bisectors of each star have been averaged. The obtained average bisectors in the stellar spectra are more or less similar to the shape C well known to the Sun. In stars with rotation speeds greater than 5 km/s the shape of the bisectors is more like /. The curvature and span of the bisectors increase with the temperature of the star. Our results confirm the known facts about strong influence of rotation velocity on the span and shape of bisectors. The average convective speed 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 the matter. It's 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 stars with greater surface gravity and greater metallicity, the average convective velocity decreases. It also decreases with star age and correlates with the speed of micro and macroturbulent movements. The results of solar flux analysis showed that absolute wavelength scales in the FTS atlases used coincide with an accuracy of about -10 m/s, except for the atlas of Hinkle, etc., whose scale 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 on average of -240 m/s. 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.

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