<p>The variability of the H<InlineEquation ID="IEq3"> <EquationSource Format="MATHML"><math> <mi>α</mi> </math></EquationSource> <EquationSource Format="TEX">$\alpha $</EquationSource> </InlineEquation> chromospheric activity of solar-like stars is investigated by using the time-domain data of the LAMOST Medium-Resolution Spectroscopic Survey (MRS). Strict screening conditions are employed to ensure the quality of the selected MRS spectra and the consistency between the H<InlineEquation ID="IEq4"> <EquationSource Format="MATHML"><math> <mi>α</mi> </math></EquationSource> <EquationSource Format="TEX">$\alpha $</EquationSource> </InlineEquation> spectra of each stellar source. We use the <InlineEquation ID="IEq5"> <EquationSource Format="MATHML"><math> <msub> <mi>R</mi> <mrow> <mi mathvariant="normal">H</mi> <mi>α</mi> </mrow> </msub> </math></EquationSource> <EquationSource Format="TEX">$R_{\mathrm{H\alpha }}$</EquationSource> </InlineEquation> index (ratio of the H<InlineEquation ID="IEq6"> <EquationSource Format="MATHML"><math> <mi>α</mi> </math></EquationSource> <EquationSource Format="TEX">$\alpha $</EquationSource> </InlineEquation> luminosity to the bolometric luminosity) to measure the H<InlineEquation ID="IEq7"> <EquationSource Format="MATHML"><math> <mi>α</mi> </math></EquationSource> <EquationSource Format="TEX">$\alpha $</EquationSource> </InlineEquation> activity intensity of a spectrum, and utilize the median of the <InlineEquation ID="IEq8"> <EquationSource Format="MATHML"><math> <msub> <mi>R</mi> <mrow> <mi mathvariant="normal">H</mi> <mi>α</mi> </mrow> </msub> </math></EquationSource> <EquationSource Format="TEX">$R_{\mathrm{H\alpha }}$</EquationSource> </InlineEquation> values of multiple observations (<InlineEquation ID="IEq9"> <EquationSource Format="MATHML"><math> <msubsup> <mi>R</mi> <mrow> <mi mathvariant="normal">H</mi> <mi>α</mi> </mrow> <mi mathvariant="normal">median</mi> </msubsup> </math></EquationSource> <EquationSource Format="TEX">$R_{\mathrm{H\alpha }}^{\mathrm{median}}$</EquationSource> </InlineEquation>) as the representative activity intensity of a stellar source. The H<InlineEquation ID="IEq10"> <EquationSource Format="MATHML"><math> <mi>α</mi> </math></EquationSource> <EquationSource Format="TEX">$\alpha $</EquationSource> </InlineEquation> variability of a stellar source is indicated by the extent of the <InlineEquation ID="IEq11"> <EquationSource Format="MATHML"><math> <msub> <mi>R</mi> <mrow> <mi mathvariant="normal">H</mi> <mi>α</mi> </mrow> </msub> </math></EquationSource> <EquationSource Format="TEX">$R_{\mathrm{H\alpha }}$</EquationSource> </InlineEquation> fluctuation (<InlineEquation ID="IEq12"> <EquationSource Format="MATHML"><math> <msubsup> <mi>R</mi> <mrow> <mi mathvariant="normal">H</mi> <mi>α</mi> </mrow> <mi mathvariant="normal">EXT</mi> </msubsup> </math></EquationSource> <EquationSource Format="TEX">$R_{\mathrm{H\alpha }}^{\mathrm{EXT}}$</EquationSource> </InlineEquation>) of multiple observations. Our sample shows that the <InlineEquation ID="IEq13"> <EquationSource Format="MATHML"><math> <msubsup> <mi>R</mi> <mrow> <mi mathvariant="normal">H</mi> <mi>α</mi> </mrow> <mi mathvariant="normal">EXT</mi> </msubsup> </math></EquationSource> <EquationSource Format="TEX">$R_{\mathrm{H\alpha }}^{\mathrm{EXT}}$</EquationSource> </InlineEquation> of solar-like stars is about one order of magnitude smaller than the <InlineEquation ID="IEq14"> <EquationSource Format="MATHML"><math> <msubsup> <mi>R</mi> <mrow> <mi mathvariant="normal">H</mi> <mi>α</mi> </mrow> <mi mathvariant="normal">median</mi> </msubsup> </math></EquationSource> <EquationSource Format="TEX">$R_{\mathrm{H\alpha }}^{\mathrm{median}}$</EquationSource> </InlineEquation>. The distribution of <InlineEquation ID="IEq15"> <EquationSource Format="MATHML"><math> <mo>log</mo> <msubsup> <mi>R</mi> <mrow> <mi mathvariant="normal">H</mi> <mi>α</mi> </mrow> <mi mathvariant="normal">EXT</mi> </msubsup> </math></EquationSource> <EquationSource Format="TEX">$\log R_{\mathrm{H\alpha }}^{\mathrm{EXT}}$</EquationSource> </InlineEquation> versus <InlineEquation ID="IEq16"> <EquationSource Format="MATHML"><math> <mo>log</mo> <msubsup> <mi>R</mi> <mrow> <mi mathvariant="normal">H</mi> <mi>α</mi> </mrow> <mi mathvariant="normal">median</mi> </msubsup> </math></EquationSource> <EquationSource Format="TEX">$\log R_{\mathrm{H\alpha }}^{\mathrm{median}}$</EquationSource> </InlineEquation> reveals the distinct behaviors between the stellar-source categories with lower (<InlineEquation ID="IEq17"> <EquationSource Format="MATHML"><math> <mo>log</mo> <msubsup> <mi>R</mi> <mrow> <mi mathvariant="normal">H</mi> <mi>α</mi> </mrow> <mi mathvariant="normal">median</mi> </msubsup> <mo><</mo> <mo>−</mo> <mn>4.85</mn> </math></EquationSource> <EquationSource Format="TEX">$\log R_{\mathrm{H\alpha }}^{\mathrm{median}} < -4.85$</EquationSource> </InlineEquation>) and higher (<InlineEquation ID="IEq18"> <EquationSource Format="MATHML"><math> <mo>log</mo> <msubsup> <mi>R</mi> <mrow> <mi mathvariant="normal">H</mi> <mi>α</mi> </mrow> <mi mathvariant="normal">median</mi> </msubsup> <mo>></mo> <mo>−</mo> <mn>4.85</mn> </math></EquationSource> <EquationSource Format="TEX">$\log R_{\mathrm{H\alpha }}^{\mathrm{median}} > -4.85$</EquationSource> </InlineEquation>) activity intensity. For the former stellar-source category, the top envelope of the distribution first increases and then decreases with <InlineEquation ID="IEq19"> <EquationSource Format="MATHML"><math> <mo>log</mo> <msubsup> <mi>R</mi> <mrow> <mi mathvariant="normal">H</mi> <mi>α</mi> </mrow> <mi mathvariant="normal">median</mi> </msubsup> </math></EquationSource> <EquationSource Format="TEX">$\log R_{\mathrm{H\alpha }}^{\mathrm{median}}$</EquationSource> </InlineEquation>; while for the latter category, the top envelope of the distribution is largely along a positive correlation line. In addition, for the stellar sources with lower activity intensity, the large-<InlineEquation ID="IEq20"> <EquationSource Format="MATHML"><math> <mo>log</mo> <msubsup> <mi>R</mi> <mrow> <mi mathvariant="normal">H</mi> <mi>α</mi> </mrow> <mi mathvariant="normal">EXT</mi> </msubsup> </math></EquationSource> <EquationSource Format="TEX">$\log R_{\mathrm{H\alpha }}^{\mathrm{EXT}}$</EquationSource> </InlineEquation> objects near the top envelope of the <InlineEquation ID="IEq21"> <EquationSource Format="MATHML"><math> <mo>log</mo> <msubsup> <mi>R</mi> <mrow> <mi mathvariant="normal">H</mi> <mi>α</mi> </mrow> <mi mathvariant="normal">EXT</mi> </msubsup> </math></EquationSource> <EquationSource Format="TEX">$\log R_{\mathrm{H\alpha }}^{\mathrm{EXT}}$</EquationSource> </InlineEquation> versus <InlineEquation ID="IEq22"> <EquationSource Format="MATHML"><math> <mo>log</mo> <msubsup> <mi>R</mi> <mrow> <mi mathvariant="normal">H</mi> <mi>α</mi> </mrow> <mi mathvariant="normal">median</mi> </msubsup> </math></EquationSource> <EquationSource Format="TEX">$\log R_{\mathrm{H\alpha }}^{\mathrm{median}}$</EquationSource> </InlineEquation> distribution tend to have long-term and regular variations of H<InlineEquation ID="IEq23"> <EquationSource Format="MATHML"><math> <mi>α</mi> </math></EquationSource> <EquationSource Format="TEX">$\alpha $</EquationSource> </InlineEquation> activity; while for the stellar sources with higher activity intensity, the H<InlineEquation ID="IEq24"> <EquationSource Format="MATHML"><math> <mi>α</mi> </math></EquationSource> <EquationSource Format="TEX">$\alpha $</EquationSource> </InlineEquation> variations are more likely to be random fluctuations.</p>

Variability of the H$\alpha $ chromospheric activity of solar-like stars revealed by the time-domain data of the LAMOST Medium-Resolution Spectroscopic Survey

期刊论文
发表日期：

2025年12月8日

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Han He,
Ali Luo,
Haotong Zhang,
Song Wang

摘要

The variability of the H $α$ $\alpha $ chromospheric activity of solar-like stars is investigated by using the time-domain data of the LAMOST Medium-Resolution Spectroscopic Survey (MRS). Strict screening conditions are employed to ensure the quality of the selected MRS spectra and the consistency between the H $α$ $\alpha $ spectra of each stellar source. We use the $R_{H α}$ $R_{\mathrm{H\alpha }}$ index (ratio of the H $α$ $\alpha $ luminosity to the bolometric luminosity) to measure the H $α$ $\alpha $ activity intensity of a spectrum, and utilize the median of the $R_{H α}$ $R_{\mathrm{H\alpha }}$ values of multiple observations ( $R_{H α}^{median}$ $R_{\mathrm{H\alpha }}^{\mathrm{median}}$ ) as the representative activity intensity of a stellar source. The H $α$ $\alpha $ variability of a stellar source is indicated by the extent of the $R_{H α}$ $R_{\mathrm{H\alpha }}$ fluctuation ( $R_{H α}^{EXT}$ $R_{\mathrm{H\alpha }}^{\mathrm{EXT}}$ ) of multiple observations. Our sample shows that the $R_{H α}^{EXT}$ $R_{\mathrm{H\alpha }}^{\mathrm{EXT}}$ of solar-like stars is about one order of magnitude smaller than the $R_{H α}^{median}$ $R_{\mathrm{H\alpha }}^{\mathrm{median}}$ . The distribution of $log R_{H α}^{EXT}$ $\log R_{\mathrm{H\alpha }}^{\mathrm{EXT}}$ versus $log R_{H α}^{median}$ $\log R_{\mathrm{H\alpha }}^{\mathrm{median}}$ reveals the distinct behaviors between the stellar-source categories with lower ( $log R_{H α}^{median} < - 4.85$ $\log R_{\mathrm{H\alpha }}^{\mathrm{median}} < -4.85$ ) and higher ( $log R_{H α}^{median} > - 4.85$ $\log R_{\mathrm{H\alpha }}^{\mathrm{median}} > -4.85$ ) activity intensity. For the former stellar-source category, the top envelope of the distribution first increases and then decreases with $log R_{H α}^{median}$ $\log R_{\mathrm{H\alpha }}^{\mathrm{median}}$ ; while for the latter category, the top envelope of the distribution is largely along a positive correlation line. In addition, for the stellar sources with lower activity intensity, the large- $log R_{H α}^{EXT}$ $\log R_{\mathrm{H\alpha }}^{\mathrm{EXT}}$ objects near the top envelope of the $log R_{H α}^{EXT}$ $\log R_{\mathrm{H\alpha }}^{\mathrm{EXT}}$ versus $log R_{H α}^{median}$ $\log R_{\mathrm{H\alpha }}^{\mathrm{median}}$ distribution tend to have long-term and regular variations of H $α$ $\alpha $ activity; while for the stellar sources with higher activity intensity, the H $α$ $\alpha $ variations are more likely to be random fluctuations.

Variability of the H\(\alpha \) chromospheric activity of solar-like stars revealed by the time-domain data of the LAMOST Medium-Resolution Spectroscopic Survey

摘要