850 SRG/eROSITA Sources in the Pleiades

Using SRG/eROSITA X-ray sky survey data and the optical catalog of 2209 Pleiades cluster members constructed from Gaia data, we have found 850 X-ray sources associated with cluster stars. More than 650 of them have been detected in X-rays for the first time. At the distance of the Pleiades the nominal sensitivity of eROSITA in this sky region corresponds to a 0. 3-2. 3 keV luminosity Lₗ 1. 6 10^28 erg s ^-1. The eROSITA sources associated with the Pleiades radiate with a total luminosity Lₗ, ₓ₎ₓ₀₋ 1. 3 10^32 erg s ^-1, which exceeds the X-ray luminosity of the quiet Sun by a million times. A strong, more than a factor of 10, X-ray variability has been recorded for 27 sources. Most of them are known as eruptive optical variable dM stars. Rₗ= (Lₗ/L₁₎₋) for Pleiades stars increases with decreasing effective stellar temperature from Rₗ-5 to Rₗ-2. The Rₗ distribution of stars is bimodal. The left peak at Rₗ-4. 3 is formed by FGK stars, while the right peak at Rₗ-3. 1 is mostly populated by M stars. The dependence of Rₗ on the Rossby number Ro is different for different spectral types. At small Rossby numbers for K and M stars Rₗ-3 and depends weakly on Ro. At Ro 0. 25 a rapid decrease in Rₗ is observed for K stars, while there are no M stars with large Rossby numbers in our sample. Most of the F and G stars lie in the range of lower values, Rₗ-4. 5, but the size of our sample is not enough to characterize in more detail the Rₗ-Ro relation for them.