Rotation and pulsation in Ap stars: first light results from TESS sectors 1 and 2

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Authors	CUNHA Margarida ANTOCI Victoria HOLDSWORTH Daniel KURTZ Don BALONA Luis BOGNAR Zsofia BOWMAN Dominic GUO Zhen KOLACZEK-SZYMANSKI Piotr LARES-MARTIZ Mariel PAUNZEN Ernst SKARKA Marek SMALLEY Barry SODOR Adam KOCHUKHOV Oleg PEPPER Joshua RICHEY-YOWELL Tyler RICKER George SEAGER Sara BUZASI Derek FOX-MACHADO Lester HASANZADEH Amir NIEMCZURA Ewa QUITRAL-MANOSALVA Paola MONTEIRO Mario STATEVA Ivanka DE CAT Peter HERNANDEZ Antonio GHASEMI Hesam HANDLER Gerald HEY Daniel MATTHEWS Jaymie NEMEC James PASCUAL-GRANADO Javier SAFARI Hossein SUAREZ Juan SZABO Robert TKACHENKO Andrew WEISS Werner
Year of publication	2019
Type	Article in Periodical
Magazine / Source	Monthly Notices of the Royal Astronomical Society
MU Faculty or unit	Faculty of Science
Citation
Web	https://academic.oup.com/mnras/article/487/3/3523/5512602
Doi	http://dx.doi.org/10.1093/mnras/stz1332
Keywords	stars: chemically peculiar; stars: individual; stars: oscillations; stars: magnetic fields; stars: variables
Description	We present the first results from the Transiting Exoplanet Survey Satellite (TESS) on the rotational and pulsational variability of magnetic chemically peculiar A-type stars. We analyse TESS 2-min cadence data from sectors 1 and 2 on a sample of 83 stars. Five new rapidly oscillating Ap (roAp) stars are announced. One of these pulsates with periods around 4.7 min, making it the shortest period roAp star known to date. Four out of the five new roAp stars are multiperiodic. Three of these and the singly periodic one show the presence of rotational mode splitting. Individual frequencies are provided in all cases. In addition, seven previously known roAp stars are analysed. Additional modes of oscillation are found in some stars, while in others we are able to distinguish the true pulsations from possible aliases present in the ground-based data. We find that the pulsation amplitude in the TESS filter is typically a factor of 6 smaller than that in the B filter, which is usually used for ground-based observations. For four roAp stars we set constraints on the inclination angle and magnetic obliquity, through the application of the oblique pulsator model. We also confirm the absence of roAp-type pulsations down to amplitude limits of 6 and 13 mu mag, respectively, in two of the best characterized non-oscillating Ap (noAp) stars. We announce 27 new rotational variables along with their rotation periods, and provide different rotation periods for seven other stars. Finally, we discuss how these results challenge state-of-the-art pulsation models for roAp stars.
Related projects:	Postdoc@MUNI