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

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 ( ~234 pc) the median eROSITA sensitivity in this sky region corresponds to a 0.3–2.3 keV luminosity LX~ 1.1× 10²⁹ 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 RX=log(LX/Lbol) distribution of Blanco 1 stars is bimodal. The left peak at RX~-4.2 is formed by FGK stars, while the right peak at RX~-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.