Simultaneous spectroscopic and TESS observations of the short-period Algol-type system: U Coronae Borealis

Abstract The H$\alpha$ spectra of the short-period Algol-type system U Corona Borealis were obtained in the primary minima during an observational period of the Transiting Exoplanet Survey Satellite (TESS) satellite. A profile was subtracted from another one that was observed after 11 orbits in the same orbital phase. The resulting H$\alpha$ “difference profile” of U CrB revealed the presence of circumstellar matter. On the other hand, because apparent disturbances did not appear in the light curve obtained from TESS, circumstellar matter observed in this study has no influence on the light curve, at least in the observational pass-band of TESS and the orbital period. The new ephemeris for the primary minimum has been determined.