TESS first look at evolved compact pulsators

Known ZZ Ceti stars of the southern ecliptic hemisphere as seen by TESS

¹ Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Konkoly Thege Miklós út 15-17, 1121 Budapest, Hungary
e-mail: bognar@konkoly.hu
² MTA CSFK Lendület Near-Field Cosmology Research Group, Hungary
³ ELTE Eötvös Loránd University, Institute of Phyiscs, Pázmány Péter sétány 1/A, 1171 Budapest, Hungary
⁴ Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA
⁵ DIRAC Institute, Department of Astronomy, University of Washington, Seattle, WA 98195-1580, USA
⁶ ARDASTELLA Research Group, Institute of Physics, Pedagogical University of Cracow, ul. Podchorżych 2, 30-084 Kraków, Poland
⁷ XCP-6, MS F-699 Los Alamos National Laboratory, Los Alamos, NM 87545, USA
⁸ Department of Astronomy, Boston University, 725 Commonwealth Ave., Boston, MA 02215, USA
⁹ Institut de Recherche en Astrophysique et Planétologie, CNRS, Université de Toulouse, CNES, 14 avenue Edouard Belin, 31400 Toulouse, France
¹⁰ Nicolaus Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw, Poland
¹¹ Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21212, USA
¹² Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney, Sydney, NSW 2006, Australia
¹³ Dr. Remeis-Sternwarte, Friedrich-Alexander Universität Erlangen-Nürnberg, Sternwartstr. 7, 96049 Bamberg, Germany
¹⁴ Universitat Politecnica de Catalunya, Departament de Fisica, c/ Esteve Terrades, 5, 08860 Castelldefels, Spain
¹⁵ Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
¹⁶ Instituto de Física y Astronomía, Universidad de Valparaiso, Gran Bretaña 1111, Playa Ancha, Valparaíso 2360102, Chile
¹⁷ Department of Astronomy, Beijing Normal University, Beijing 100875, PR China

Received: 9 January 2020
Accepted: 24 March 2020

Abstract

Context. We present our findings on 18 previously known ZZ Ceti stars observed by the TESS space telescope in 120 s cadence mode during the survey observation of the southern ecliptic hemisphere.

Aims. We focus on the frequency analysis of the space-based observations, comparing the results with findings of previous ground-based measurements. The frequencies detected by the TESS observations can serve as inputs for future asteroseismic analyses.

Methods. We performed standard pre-whitening of the data sets to derive the possible pulsation frequencies of the different targets. In some cases, we fit Lorentzians to the frequency groups that emerged as the result of short-term amplitude or phase variations that occurred during the TESS observations.

Results. We detected more than 40 pulsation frequencies in seven ZZ Ceti stars observed in the 120 s cadence by TESS, with precision better than 0.1 μHz. We found that HE 0532−5605 may be a new outbursting ZZ Ceti. Ten targets do not show any significant pulsation frequencies in their Fourier transforms, due to a combination of their intrinsic faintness and/or crowding on the large TESS pixels. We also detected possible amplitude or phase variations during the TESS observations in some cases. Such behaviour in these targets was not previously identified from ground-based observations.