Rapidly oscillating Ap stars observed with TESS

The LAMOST Ap sample and 49 Cam

¹ Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
² Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal
³ South African Astronomical Observatory, PO Box 9, Observatory, 7935, Cape Town, South Africa
⁴ School of Physics, Engineering and Technology, University of York, Heslington, York, YO10 5DD, UK
⁵ DTU Space, Technical University of Denmark, Elektrovej 327, Kgs., Lyngby 2800, Denmark
⁶ Centre for Space Research, North-West University, Dr Albert Luthuli Drive, Mahikeng 2735, South Africa
⁷ Jeremiah Horrocks Institute, University of Lancashire, Preston PR1 2HE, UK
⁸ Department of Astronomy, Cornell University, 122 Sciences Drive, Ithaca, NY 14853, USA
⁹ Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191 Gif-Sur-Yvette, France

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 22 January 2026
Accepted: 21 April 2026

Abstract

Context. The rapidly oscillating chemically peculiar A-type (roAp) stars offer valuable insights into the internal physical processes of all stars, but their study is challenged by their rarity. The large-scale Transiting Exoplanet Survey Satellite (TESS) and Gaia surveys have allowed for the collection of data for a sizeable dataset of roAp stars. Nevertheless, asteroseismic data obtained with TESS have not been explored to their full potential.

Aims. We develop an algorithm capable of analysing large quantities of TESS data to search for new roAp stars and increase the current sample. We focus on data products that have not been previously explored for the search of roAp stars, namely the TESS 200-s full frame images (FFIs) and 20-s cadence light curves.

Methods. The 20-s and 200-s cadence light curves of target stars were retrieved from the Mikulski Archive for Space Telescopes (MAST) server and cleaned. Discrete Fourier transforms (DFTs) were computed for each light curve, which were used to pre-whiten the data to remove any low-frequency signals. A final DFT was calculated, which was used to classify stars as non-pulsating (NP), δ Scuti, or roAp based on the remaining signal.

Results. We applied our algorithm to two independent datasets: (i) ∼2700 Ap stars spectroscopically classified with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and observed by TESS in the 200-s FFIs and (ii) all TESS 20-s cadence light curves available for known or candidate roAp stars. These two samples have no overlap, i.e. none of the LAMOST stars have been observed with 20-s cadence. We identify four new roAp stars: TIC 312111544, TIC 252881095, TIC 46054683, and 49 Cam (TIC 393276640). We find evidence in TESS data that TIC 252881095 may be part of a binary system. If the tentative ∼30-d orbital signal is confirmed, TIC 252881095 could be one of the shortest-period roAp binaries currently known. Furthermore, the detection of high-frequency pulsations in 49 Cam is particularly relevant, as this well-known roAp candidate star is here confirmed to be roAp based on TESS 20-s cadence data.