J/A+A/666/A142ivo://CDS.VizieR/J/A+A/666/A142doi:10.26093/cds/vizier.36660142CDSSkarka M.Zak J.Fedurco M.Paunzen E.Henzl Z.Masek M.,Karjalainen R.Sanchez Arias J.P.Sodor A.Auer R.F.Kabath P.,Karjalainen M.Liska J.Stegner D.2023-07-03T14:35:55Z2022-10-19T09:15:42ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frvariable-starsf-starsIn the time of large space surveys that provide tremendous amounts of precise data, it is highly desirable to have a commonly accepted methodology and system for the classification of variable stars. This is especially important for A-F stars, which can show intrinsic brightness variations due to both rotation and pulsations. The goal of our study is to provide a reliable classification of the variability of A-F stars brighter than 11 mag located in the northern TESS continuous viewing zone. We also aim to provide a thorough discussion about issues in the classification related to data characteristics and the issues arising from the similar light-curve shape generated by different physical mechanisms. We used TESS long- and short-cadence photometric data and corresponding Fourier transform to classify the variability type of the stars. We also used spectroscopic observations to determine the projected rotational velocity of a few stars. We present a clear and concise classification system that is demonstrated on many examples. We find clear signs of variability in 3025 of 5923 studied stars (51%). For 1813 of these 3025 stars, we provide a classification; the rest cannot be unambiguously classified. Of the classified stars, 64.5% are pulsating stars of g-mode {gamma} Doradus (GDOR) and p-mode {delta} Scuti types and their hybrids. We realised that the long- and short-cadence pre-search data conditioning simple aperture photometry data can differ significantly not only in amplitude but also in the content of instrumental and data-reduction artefacts, making the long-cadence data less reliable. We identified a new group of stars that show stable light curves and characteristic frequency spectrum patterns (8.5% of the classified stars). According to the position in the Hertzsprung-Russell diagram, these stars are likely GDOR stars but are on average about 200K cooler than GDORs and have smaller amplitudes and longer periods. With the help of spectroscopic measurements of vsini, we show that the variability of stars with unresolved groups of peaks located close to the positions of the harmonics in their frequency spectra (16% of the classified stars) can be caused by rotation rather than by pulsations. We show that without spectroscopic observations it can be impossible to unambiguously distinguish between ellipsoidal variability and rotational variability. We also applied our methodology to three previous studies and find significant discrepancies in the classification.2022A&A...666A.142Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/666/A142CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)B/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-2014)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/666/A142https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/666/A142http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/666/A142https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/666/A142https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/666/A142http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/666/A142GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/666/A142/table5 (Classification of A-F spectral type stars in the northern TESS viewing zone)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/666/A142/table5?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/666/A142/table5?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/666/A142/table5?GETtext/xml+votable180.050000true272.6882556262553.500384862020.0055555555555555563/159 183 239 250-251 4/629 631 721 723-724 726-727 729 731 756-757 954-955 994-995 998-999 1016 1018 5/2515 2521-2523 2533 2535 2541-2543 2883 2889 2891 2900 2902-2903 2913 2915 2921 3012-3013 3015 3032-3033 3036-3037 3775 3803 3805-3807 3811 3813-3815 3971 3974-3975 3986-3987 3990 4040 4042-4043 4068 4070 4076 4078 6/9717 9719 9721 9723-9725 9727 10047 10055 10081-10083 10139 10159 10161-10163 11525 11527 11604-11605 11607 11692-11693 11695 12037 12056-12057 12059 12084-12085 12141 12152 15093-15095 15098-15099 15166-15167 15199 15206-15207 15209-15211 15217-15219 15243 15249-15251 15882-15883 15895 15939 15964 15966-15967 16138 16164 16166-16167 16186 16286 16308https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/666/A142?format=asciidefaultJ/A+A/666/A142/table5Classification of A-F spectral type stars in the northern TESS viewing zonerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameNumber in the TIC catalogue (Paegert et al., 2021, Cat. IV/39)meta.id;meta.mainRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainVTypeVariability typemeta.notecharSpTypeSpectral typesrc.spTypecharf? Dominant frequencyc.d**-1em.freqdoublenullableM0? Zero epoch (MJD)dtime.epochdoublenullablel_dTLimit flag on dTmeta.code.errorchardT? Amplitude of the light variationsmmagphys.composition.massLightRatiofloatnullableVSXDesignation of the variable star in VSX (Watson et al, 2014, Cat. B/vsx)meta.id;phys.atmol.configurationcharVSXtypeVSX variability typemeta.notecharBlend? TIC designation of the blending star that is variablemeta.id.assoclongnullableN? Number of blending stars with brightness difference less than 5magmeta.numberintnullable