J/MNRAS/448/464ivo://CDS.VizieR/J/MNRAS/448/464doi:10.26093/cds/vizier.74480464CDSTakayama M.Wood P.R.Ita Y.2024-08-14T20:20:37Z2017-11-16T13:07:53ZCDS support team

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

cds-question@unistra.frmagellanic-cloudsgiant-starsinfrared-photometryvisible-astronomyphotometryeffective-temperaturestellar-spectral-typesLong-term JHK light curves have recently become available for large numbers of the more luminous stars in the Small Magellanic Cloud (SMC). We have used these JHK light curves, along with OGLE (Optical Gravitational Lensing Experiment) V and I light curves, to examine the variability of a sample of luminous red giants in the SMC which show prominent long secondary periods (LSPs). The origin of the LSPs is currently unknown. In oxygen-rich stars, we found that while most broad-band colours (e.g. V- I) get redder when an oxygen-rich star dims during its LSP cycle, the J-K colour barely changes and sometimes becomes bluer. We interpret the J-K colour changes as being due to increasing water vapour absorption during declining light caused by the development of a layer of dense cool gas above the photosphere. This result and previous observations which indicate the development of a chromosphere between minimum to maximum light suggest that the LSP phenomenon is associated with the ejection of matter from the stellar photosphere near the beginning of light decline. We explore the possibility that broad-band light variations from the optical to the near-infrared regions can be explained by either dust absorption by ejected matter or large spots on a rotating stellar surface. However, neither model is capable of explaining the observed light variations in a variety of colour-magnitude diagrams. We conclude that some other mechanism is responsible for the light variations associated with LSPs in red giants.2015MNRAS.448..464Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/448/464CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/288 : IRSF Magellanic Clouds Point Source Catalog (Kato+ 2007)J/A+A/401/873 : The SMC in the Far Infrared (Wilke+, 2003)J/AcA/61/217 : VI light curves of SMC long-period variables (Soszynski+, 2011)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/448/464https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/448/464http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/448/464https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/448/464https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/448/464http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/448/464GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/448/464/table1 (Basic parameters of the program stars at maximum light)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/448/464/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/448/464/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/448/464/table1?GETtext/xml+votable180.050000true12.40254-72.970750.0055555555555555566/33293 33295 333177.952274030004205e-20 3.852589004194616e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/448/464?format=asciiOpticalInfrareddefaultJ/MNRAS/448/464/table1Basic parameters of the program stars at maximum lightrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameName (OGLE SMC-LPV-NNNNN in Simbad)meta.id;meta.maincharRAJ2000Right Ascension in decimal degrees (J2000)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000)degpos.eq.dec;meta.mainVmag? OGLE V-band magnitudemagphot.mag;em.opt.VfloatnullableImagOGLE I-band magnitudemagphot.mag;em.opt.IfloatJmagIRSF J-band magnitudemagphot.mag;em.IR.JfloatHmagIRSF H-band magnitudemagphot.mag;em.IR.HfloatKsmagIRSF K_S_-band magnitudemagphot.mag;em.IR.KfloatLLuminosity derived by applying a bolometric correction to K_s_ (see Section 4.1)solLumphys.luminosityintTBBBlackbody temperature derived from J-K_S_Kphys.temperatureintTeffEffective temperature derived from J-K_S_ using the formula in Bessell, Wood & Evans (1983MNRAS.202...59B)Kphys.temperature.effectiveintPLSPProminent long secondary period (LSP)dtime.periodintSpType[OC] Spectral type (Oxygen or Carbon-rich)src.spTypecharFileNameJJ light curve filemeta.ref.urlcharFileNameHH light curve filemeta.ref.urlcharFileNameKK light curve filemeta.ref.urlcharLCLight curvesmeta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlchar