A catalogue of binary stars from phase modulation in the first four years of <i>TESS</i> mission photometry

ABSTRACT We present a catalogue of binary companions to $\delta$ Scuti stars, detected through phase modulations of their pulsations in Transiting Exoplanet Survey Satellite (TESS) data. Pulsation timing has provided orbits for hundreds of pulsating stars in binaries from space-based photometry. We have applied this technique to $\delta$ Sct stars observed in the first four years of TESS mission photometry. We searched the 2-min cadence light curves of 1161 short-period instability strip pulsators for variations in pulsation phase caused by the dynamical influence of an unseen companion. We discovered 53 new binaries and we present orbital parameters and mass functions for the 24 systems with solvable orbits. For the brightest star in our sample $\alpha$ Pictoris, we perform a joint fit of the pulsation timing and Hipparcos astrometry. We present the first orbit for the $\alpha$ Pictoris system, obtaining an orbital period of 1316 $\pm$ 2 d and a mass for $\alpha$ Pic B of 1.05 $\pm$ 0.05 M$_\odot$. We revisit pulsation timing binaries from Kepler with Gaia kinematics, finding four systems that are members of the Galactic thick disc or halo. This suggests that they have been rejuvenated by mass transfer, and their companions are now white dwarfs. Further follow-up of these systems may yield valuable constraints of the Galactic blue straggler population.