J/A+A/676/A28ivo://CDS.VizieR/J/A+A/676/A28doi:10.26093/cds/vizier.36760028CDSTarczay-Nehez D.Molnar L.Bodi A.Szabo R.2024-11-28T20:04:49Z2023-07-31T07:56:09ZCDS support team

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

cds-question@unistra.frvariable-starsphotometryvisible-astronomyUltra-low amplitude (ULA) and strange mode Cepheids are thought to be pulsating variable stars that are near to or are at the edges of the classical instability strip. Until now, a few dozen such variable star candidates have been found both in the Large Magellanic Cloud and the Milky Way. In this present work, we studied six ULA Cepheid candidates in the Milky Way, identified by Szabo et al. (2009, in American Institute of Physics Conference Series, Vol. 1170, Stellar Pulsation: Challenges for Theory and Observation, ed. J.A. Guzik & P.A. Bradley, 102-104) using CoRoT and 2MASS data. In order to identify their positions in the period--luminosity and color-magnitude diagrams, we used the Gaia DR3 parallax and brightness data of each star to calculate their reddening-free absolute magnitudes and distances. Furthermore, we calculated the Fourier parameters (e.g., period and amplitude) of the light variations based on CoRoT and TESS measurements, and established the long-term phase shifts for four out of six stars. Based on the results, we conclude that none of the six ULA Cepheid candidates are pulsating variable stars, but rather rotation-induced variable stars (rotational spotted and alpha^2^ Canum Venaticorum variables) that are either bluer or fainter than Cepheids would be.2023A&A...676A..28Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/676/A28CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/corot : CoRoT observation log (N2-4.4) (CoRoT, 2016)IV/38 : TESS Input Catalog - v8.0 (TIC-8) (Stassun+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/676/A28https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/676/A28http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/676/A28https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/676/A28https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/676/A28http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/676/A28GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/676/A28/stars (List of studied stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/676/A28/stars?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/676/A28/stars?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/676/A28/stars?GETtext/xml+votable180.050000true101.74965-0.510.0055555555555555566/22070-22071 22077 22079https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/676/A28?format=asciiOpticaldefaultJ/A+A/676/A28/starsList of studied starsCoRoTCoRoT identifiermeta.id;meta.mainlongrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintClcShow the CoRoT light curvemeta.ref.urlcharTlcShow the TESS light curvemeta.ref.urlcharRAJ2000Right ascension (J2000) (from table 1)degpos.eq.ra;meta.mainDEJ2000Declination (J2000) (from table 1)degpos.eq.dec;meta.mainPerPeriod (from table 1)dtime.periodfloatTICTESS identifier (from table 3)meta.idlongGaiaDR3Gaia DR3 identifier (from table 3)meta.id2MASS2MASS identifier (HHMMSSss+DDMMSSs) (from table 2)meta.idcharJ/A+A/676/A28/tablea1CoRoT light curvesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintCoRoTCoRoT IDmeta.id;meta.mainlongBJDBarycentic Julian date of the measurementdtime.epochdoubleindexedWmagCoRoT white magnitudemagphot.mag;em.optfloate_WmagError of CoRoT white magnitudemagstat.error;phot.magfloatRunRunmeta.notecharJ/A+A/676/A28/tablea2TESS light curvesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintCoRoTCoRoT IDmeta.id;meta.mainlongBJDBarycentic Julian date of the measurementdtime.epochdoubleindexedTmagTESS magnitudemagphot.mag;em.optfloate_TmagError of CoRoT white magnitudemagstat.error;phot.magfloatSectorSector IDobs.fieldchar