TYC 8380-1953-1: Discovery of an RS CVn Binary Through the XMM-Newton Slew Survey

In this article we report the discovery of the chromospherically active (RS CVn type) binary TYC 8380-1953-1 through the XMM-Newton slew survey and present results of our optical and X-ray follow-up. With a flux limit of 6 × 10^-13 ergs cm^-2 s^-1 in the soft band (0.2-2 keV), the XMM-Newton slew has a similar sensitivity to the ROSAT All Sky Survey, allowing interesting sources to be identified by their long-term variability. Two different types of stellar sources are detected in shallow X-ray surveys: young stars (both pre-main- and main-sequence stars) and chromospherically active binaries (BY Dra and RS CVn-type systems). The discovery of stars in such surveys and the study of their nature through optical follow-ups is valuable to determine their spatial distribution and scale height in the Galaxy. Our analysis shows that TYC 8380-1953-1 is a double-lined spectroscopic binary, with both components having similar spectral type (likely K0/2 + K3/5) and luminosity. With a typical coronal temperature for an RS CVn system (kT ∼ 1.15 keV) and an X-ray luminosity in the 0.3-10 keV energy band higher than 4 × 10³¹ erg s^-1, TYC 8380-1953-1 lies among the most X-ray luminous RS CVn binaries.