J/ApJ/824/74ivo://CDS.VizieR/J/ApJ/824/74doi:10.26093/cds/vizier.18240074CDSGarcia-Varela A.Munoz J.R.Sabogal B.E.Vargas Dominguez S.,Martinez J.2017-10-13T15:41:25Z2016-09-28T08:20:33ZCDS support team

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

cds-question@unistra.frmagellanic-cloudsvariable-starsThe investigation of the nonlinearity of the Leavitt law (LL) is a topic that began more than seven decades ago, when some of the studies in this field found that the LL has a break at about 10 days. The goal of this work is to investigate a possible statistical cause of this nonlinearity. By applying linear regressions to OGLE-II and OGLE-IV data, we find that to obtain the LL by using linear regression, robust techniques to deal with influential points and/or outliers are needed instead of the ordinary least-squares regression traditionally used. In particular, by using M- and MM-regressions we establish firmly and without doubt the linearity of the LL in the Large Magellanic Cloud, without rejecting or excluding Cepheid data from the analysis. This implies that light curves of Cepheids suggesting blending, bumps, eclipses, or period changes do not affect the LL for this galaxy. For the Small Magellanic Cloud, when including Cepheids of this kind, it is not possible to find an adequate model, probably because of the geometry of the galaxy. In that case, a possible influence of these stars could exist.2016ApJ...824...74Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/824/74CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AcA/62/219 : OGLE: Gaia South Ecliptic Pole Field (Soszynski+, 2012)J/AcA/60/17 : VI light curves of SMC classical Cepheids (Soszynski+, 2010)J/other/A+ARV/17.251 : Stars observed with Doppler imaging (Strassmeier, 2009)J/AcA/58/313 : LMC Cepheids in OGLE and MACHO data (Poleski+, 2008)J/AcA/58/163 : VI light curves of LMC classical Cepheids (Soszynski+, 2008)J/A+A/476/73 : Calibration of Cepheid Per/Lum relation (Fouque+, 2007)J/AJ/131/2514 : Radial velocities of red giants in the SMC (Harris+, 2006)J/AJ/128/2815 : ARAUCARIA project: NGC 6822 Cepheids (Pietrzynski+, 2004)J/A+A/404/423 : BVI photometry of Galactic Cepheids (Tammann+, 2003)J/AcA/51/221 : OGLE-II. Cepheids in IC 1613 (Udalski+, 2001)J/AcA/49/543 : OGLE LMC + SMC Cepheids VI photometry (Pietrzynski+, 1999)J/AcA/49/437 : BVI photometry of OGLE SMC Cepheids (Udalski+, 1999)J/AcA/49/223 : BVI photometry of OGLE LMC Cepheids (Udalski+, 1999)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/824/74https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/824/74http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/824/74https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/824/74https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/824/74http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/824/74GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/824/74/table2 (Bi-dimensional classification of OGLE-II Magellanic Clouds Cepheids)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/824/74/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/824/74/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/824/74/table2?GETtext/xml+votable180.050000true9.043375-73.94441670.0055555555555555565/8272 8274 6/33053 33077 33120 33121 33294 33295 33304 33306 33316 33317 33328https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/824/74?format=asciidefaultJ/ApJ/824/74/table2Bi-dimensional classification of OGLE-II Magellanic Clouds CepheidsFieldOGLE-II field (1)meta.id;obs.fieldcharPeriod[0.9/49.8] Perioddtime.perioddoublerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000[0/5] Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000[68/73] Degree of Declination (J2000)pos.eq.dec;meta.mainID[1/472701] OGLE-II identifier (1)meta.id;meta.mainintClassThe bi-dimensional class (2)src.classcharf_Class"i" identifies the influential Cepheidsmeta.codecharSimbadSimbad column added by the CDSmeta.ref.urlchar