Abstract <p>Using data from the all-sky X-ray survey with the eROSITA telescope onboard the SRG orbital observatory and the optical catalog of Blanco 1 cluster members constructed from Gaia data, we have investigated the X-ray emission from cluster stars. Of the 723 cluster members located in the eastern Galactic part of the sky, eROSITA detects X-ray emission from 110 stars, thereby increasing the number of known sources by more than a factor of 2. At the Blanco 1 distance (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\({\sim}234\)</EquationSource>  </InlineEquation> pc) the median eROSITA sensitivity in this sky region corresponds to a 0.3–2.3 keV luminosity <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(L_{X}\sim 1.1\times 10^{29}\)</EquationSource>  </InlineEquation> erg s<InlineEquation ID="IEq3"> <EquationSource Format="TEX">\({}^{-1}\)</EquationSource>  </InlineEquation>, allowing more than 60<InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\%\)</EquationSource>  </InlineEquation> of the solar-type stars to be detected within the Blanco 1 tidal radius. For one source a strong (more than a factor of 10) X-ray variability on a time scale of six months has been recorded. This is a late-M star. The <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(R_{X}=\log(L_{X}/L_{\textrm{bol}})\)</EquationSource>  </InlineEquation> distribution of Blanco 1 stars is bimodal. The left peak at <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(R_{X}\sim{-}4.2\)</EquationSource>  </InlineEquation> is formed by FGK stars, while the right peak at <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(R_{X}\sim{-}3.1\)</EquationSource>  </InlineEquation> consists predominantly of K and M stars. A comparison of the properties of X-ray sources in the similarly aged Blanco 1 and Pleiades clusters has shown a high level of consistency, pointing to a common evolutionary scenario for the X-ray activity of stars in these clusters.</p>

Coronal Activity of Stars in the Blanco 1 Open Cluster from SRG/eROSITA All-Sky Survey Data

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发表日期：

2025年9月1日

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I. M. Khamitov,
I. F. Bikmaev,
M. R. Gilfanov,
R. A. Sunyaev,
M. A. Gorbachev,
S. S. Panarin,
P. S. Medvedev

摘要

Abstract

Using data from the all-sky X-ray survey with the eROSITA telescope onboard the SRG orbital observatory and the optical catalog of Blanco 1 cluster members constructed from Gaia data, we have investigated the X-ray emission from cluster stars. Of the 723 cluster members located in the eastern Galactic part of the sky, eROSITA detects X-ray emission from 110 stars, thereby increasing the number of known sources by more than a factor of 2. At the Blanco 1 distance ( \({\sim}234\) pc) the median eROSITA sensitivity in this sky region corresponds to a 0.3–2.3 keV luminosity \(L_{X}\sim 1.1\times 10^{29}\) erg s \({}^{-1}\) , allowing more than 60 \(\%\) of the solar-type stars to be detected within the Blanco 1 tidal radius. For one source a strong (more than a factor of 10) X-ray variability on a time scale of six months has been recorded. This is a late-M star. The \(R_{X}=\log(L_{X}/L_{\textrm{bol}})\) distribution of Blanco 1 stars is bimodal. The left peak at \(R_{X}\sim{-}4.2\) is formed by FGK stars, while the right peak at \(R_{X}\sim{-}3.1\) consists predominantly of K and M stars. A comparison of the properties of X-ray sources in the similarly aged Blanco 1 and Pleiades clusters has shown a high level of consistency, pointing to a common evolutionary scenario for the X-ray activity of stars in these clusters.