Two New roAp Stars Discovered with TESS

TL;DR

This paper reports the discovery of two new rapidly oscillating Ap stars using TESS photometric data, demonstrating TESS's effectiveness in identifying high-frequency pulsators without the need for spectroscopy.

Contribution

The study introduces two newly identified roAp stars from TESS data, expanding the catalog of such pulsators and showcasing TESS's capability for high-frequency star detection.

Findings

Discovered two new roAp stars with distinct pulsation modes.

Identified high-overtone pressure modes and rotationally split dipole modes.

Confirmed TESS's effectiveness in detecting pulsators without spectroscopy.

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.