TESS observations of TX Col: Rapidly varying accretion flow

Abstract: Using the first long-term photometry from the Transiting Exoplanet Survey Satellite, we have carried out a detailed time-resolved timing analysis of an intermediate polar TX Col. The power spectra of almost 52 days continuous time-series data reveal the orbital period of $5.691 \pm 0.006$ hr, spin period of $1909.5 \pm 0.2$ s, and beat period of $2105.76 \pm 0.25$ s, which is consistent with the earlier results. We have also found the presence of quasi-periodic oscillations (QPOs) for a few days with a period of 5850-5950 s, which appears to be due to the beating of the Keplerian period with the spin period of the white dwarf. The continuous data allowed us to look thoroughly at the day-wise evolution of the system's accretion geometry. We report here that the TX Col changes its accretion mechanism even on a time-scale of one day, confirming its variable disk-overflow accretion nature. For the majority of the time, it was found to be disk-overflow system with stream-fed dominance, however, pure disk-fed and pure stream-fed accretions cannot be ruled out during the observations.