论文标题
基于低分辨率光谱调查，使用变异自动编码器对恒星磁活动进行研究
Investigation of stellar magnetic activity using variational autoencoder based on low-resolution spectroscopic survey
论文作者
论文摘要
我们将变异自动编码器（VAE）应用于Lamost-K2低分辨率光谱，以检测K2场中恒星的磁活性。在对所选无活跃恒星的光谱进行训练之后，VAE模型可以有效地生成光谱减法程序所需的合成参考模板，而不知道任何恒星参数。然后，我们在样品中检测到特殊的光谱特征，例如色圈发射，强雾发射和锂吸收。我们测量色球活性指标，H $α$和CA II红外三重态（IRT）线的排放，以量化恒星磁性活性。活性星的H $α$和Ca II IRT线的过量排放与旋转周期和源自K2光度法得出的光曲线的振幅非常相关。我们降低了LAMOST光谱，以模拟中国空间站望远镜（CSST）的无狭窄光谱，并将VAE应用于模拟数据。对于凉爽的活跃恒星，我们揭示了从光谱中以两种分辨率得出的H $α$线的等效宽度（EWS）之间的良好一致性。结果表明，在未来的CSST调查中鉴定磁性恒星的能力，该恒星将提供前所未有的大型低分辨率光谱数据库以及同时的恒星多波段光度法。
We apply the variational autoencoder (VAE) to the LAMOST-K2 low-resolution spectra to detect the magnetic activity of the stars in the K2 field. After the training on the spectra of the selected inactive stars, the VAE model can efficiently generate the synthetic reference templates needed by the spectral subtraction procedure, without knowing any stellar parameters. Then we detect the peculiar spectral features, such as chromospheric emissions, strong nebular emissions and lithium absorptions, in our sample. We measure the emissions of the chromospheric activity indicators, H$α$ and Ca II infrared triplet (IRT) lines, to quantify the stellar magnetic activity. The excess emissions of H$α$ and Ca II IRT lines of the active stars are correlated well to the rotational periods and the amplitudes of light curves derived from the K2 photometry. We degrade the LAMOST spectra to simulate the slitless spectra of the China Space Station Telescope (CSST) and apply the VAE to the simulated data. For cool active stars, we reveal a good agreement between the equivalent widths (EWs) of H$α$ line derived from the spectra with two resolutions. The result indicates the ability of identifying the magnetically active stars in the future CSST survey, which will deliver an unprecedented large database of low-resolution spectra as well as simultaneous multi-band photometry of stars.
