The contact binary system TYC 7275-1968-1 as seen by optical, UV and X-ray observations.

We present an analysis of publicly available X-ray and optical observations of TYC 7275-1968-1, a contact binary, red nova progenitor candidate. The long optical time series of ASAS-3 , SuperWASP , CRTS , Gaia , ASAS-SN , and TESS enabled us to improve its orbital period to 0.3828071 ± 0.0000026 d. We show the presence of an X-ray and UV source associated with TYC 7275-1968-1 from Neil Gehrels Swift Observatory, that was previously assumed to be the counterpart of CD -36 8436 (V1044 Cen), a symbiotic star located 22 arcsec from the red nova candidate. The X-ray data indicate the presence of a region with a temperature of k T = 0.8 − 0. 1 + 0. 9 keV and a luminosity of 1.4 − 0. 2 + 0. 1 × 1031 erg s −1 in the range 0.3 – 10 keV. The detection of X-rays and modulated UV emission suggests that both components of the binary are chromospherically active. • TYC 7275-1968-1 is a binary eclipsing system suggested as red novae progenitor. • Swift and TESS data are related to red nova progenitor and not for CD-36 8436. • We improved the orbital period of TYC 7275-1968-1 using the TESS data. • The period found is considered as limits to orbital instability. • The X-ray emission originates in a corona around the contact binary. [ABSTRACT FROM AUTHOR]