Two New roAp Stars Discovered with TESS

Abstract

We present two new rapidly oscillating Ap (roAp) stars, TIC 198781841 and TIC 229960986, discovered in TESS photometric data. The periodogram of TIC 198781841 has a large peak at 166.506 d${}^{-1}$ (1.93 mHz), with two nearby peaks at 163.412 d${}^{-1}$ (1.89 mHz) and 169.600 d${}^{-1}$ (1.96 mHz). These correspond to three independent high-overtone pressure modes, with alternating even and odd $\ell$ values. TIC 229960986 has a high-frequency triplet centered at 191.641 d${}^{-1}$ (2.218 mHz), with sidebands at 191.164 d${}^{-1}$ (2.213 mHz) and 192.119 d${}^{-1}$ (2.224 mHz). This pulsation appears to be a rotationally split dipole mode, with sideband amplitudes significantly larger than that of the central peak; hence, both pulsation poles are seen over the rotation cycle. Our photometric identification of two new roAp stars underscores the remarkable ability of TESS to identify high-frequency pulsators without spectroscopic observations.

4 pages, 1 figure, accepted for publication in RNAAS