SIMBAD references

Based on a comparison of the SRG/eROSITA catalog of X-ray active stars and the Gaia catalog, we have obtained a sample of 502 peculiar objects for which Gaia, on the one hand, detects statistically significant parallaxes or proper motions and, on the other hand, records signs of a nonzero optical extent. On the F_X/F_opt −colordiagram these objects are significantly separated from the bulk of the stars and are located in the region typical for active galactic nuclei (AGNs). According to the SIMBADdatabase, ≈50% of them are AGNs and galaxies with spectroscopic redshifts and only ∼ 1.4% are confirmed objects in our Galaxy. Our spectroscopic observations of 19 unidentified objects with the RTT−150 telescope have shown that 18 of them are AGNs at redshifts∼0.01-0.3 and one object is an M star in our Galaxy. We discuss various scenarios for the appearance of such peculiar objects.