J/A+AS/71/297ivo://CDS.VizieR/J/A+AS/71/297CDSAparicio A.Garcia-Pelayo J.M.Moles M.Melnick J.2011-02-07T13:24:12Z2011-01-14T12:49:24ZCDS support team

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

cds-question@unistra.frgalaxiesphotometryvisible-astronomyWide-band photometryccd-photometryCCD UBV photometry of 2279 stars in Sextans A is presented. Differences with the photometric scales of Sandage and Carlson (1985AJ.....90.1019S) and Hoessel et al. (1983ApJ...274..577H) are discussed; recalibration of the Sandage and Carlson data for Cepheids in Sextans A results in a smaller value for the distance modulus, {mu}=25.6. A similar value for the distance modulus is obtained from the colour-colour diagram. Colour-colour and colour-magnitude diagrams for the whole galaxy and for different parts are presented indicating a general star formation activity all over Sextans A. The contribution of stars brighter than M_pg_=-3 to the total blue light of the galaxy amounts to 25%, a much higher value than what is found for other dwarf irregular galaxies in the Local Group. The integrated birthrate per unit mass of massive stars for the galaxy is found to be much higher than in the Magellanic Clouds, suggesting that the rate in Sextans A was probably smaller in the past. Different slopes for high mass and low mass IMF parts are needed to account for its low surface brightness. The formation of massive stars seems to be favoured for systems of decreasing mass or, given the relation between total mass and metal content, for galaxies of decreasing metallicity.1987A&AS...71..297Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+AS/71/297CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/116/2341 : UBVRI photometry in Sextans A (Van Dyk+ 1998)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+AS/71/297https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+AS/71/297http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+AS/71/297https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+AS/71/297https://vizier.iucaa.in/viz-bin/votable?-source=J/A+AS/71/297http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+AS/71/297GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+AS/71/297/table2 (CCD UBV photometry results)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+AS/71/297/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+AS/71/297/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+AS/71/297/table2?GETtext/xml+votable180.050000true152.764705-4.73447920.0055555555555555566/26858https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+AS/71/297?format=asciiOpticaldefaultJ/A+AS/71/297/table2CCD UBV photometry resultsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintAGM[1/2279]+ Sequential number (\dicS{AGM Sextans A NNNN} in Simbad)meta.recordintprimaryindexedXposX position (1)pixpos.cartesian.x;instr.detfloatYposY position (1)pixpos.cartesian.y;instr.detfloatU-B? U-B colour indexmagphot.color;em.opt.U;em.opt.Bfloatnullablee_U-B? rms uncertainty on U-Bmagstat.error;phot.color;em.opt.UfloatnullableB-VB-V colour indexmagphot.color;em.opt.B;em.opt.Vfloate_B-Vrms uncertainty on B-Vmagstat.error;phot.color;em.opt.BfloatVmagV magnitudemagphot.mag;em.opt.Vfloate_Vmagrms uncertainty on Vmagmagstat.error;phot.mag;em.opt.Vfloat_RAPosition computed from a comparison with Van Dyk et al. 1998, Cat. J/AJ/116/2341 ({sigma}=0.13'') (right ascension part)degpos.eq.ra;meta.main_DEPosition computed from a comparison with Van Dyk et al. 1998, Cat. J/AJ/116/2341 ({sigma}=0.13'') (declination part)degpos.eq.dec;meta.main