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Date and Time of the Query: 2018-07-20 T07:08:07 PDT
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For refcode 2007AJ....133.2393M:
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2007AJ....133.2393M A Survey of Local Group Galaxies Currently Forming Stars. II. UBVRI Photometry of Stars in Seven Dwarfs and a Comparison of the Entire Sample Philip Massey, K. A. G. Olsen, Paul W. Hodge, George H. Jacoby, Reagin T. McNeill, R. C. Smith, and Shay B. Strong Abstract. We have obtained UBVRI images with the Kitt Peak National Observatory and Cerro Tololo Inter-American Observatory 4 m telescopes and Mosaic cameras of seven dwarfs in (or near) the Local Group, all of which have known evidence of recent star formation: IC 10, NGC 6822, WLM, Sextans B, Sextans A, Pegasus, and Phoenix. We construct color-magnitude diagrams (CMDs) of these systems, as well as neighboring regions that can be used to evaluate the degree of foreground contamination by stars in the Milky Way. Intercomparison of these CMDs with those of M31, M33, the LMC, and the SMC permits us to determine improved reddening values for a typical OB star found within these galaxies. All of the CMDs reveal a strong or modest number of blue supergiants. All but Pegasus and Phoenix also show the clear presence of red supergiants in the CMD, although IC 10 appears to be deficient in these objects given its large Wolf-Rayet star population. The bright stars of intermediate color in the CMD are badly contaminated by foreground stars (30% -- 100%), and considerable spectroscopy is needed before statistics on the yellow supergiants in these systems will be known. This study is intended to serve as both the impetus and "finding charts" for further space-based imaging and for many spectroscopic programs at large aperture. Key words: Catalogs, Galaxies: Stellar Content, Stars: Early-Type, Stars: Supergiants, Surveys =========================================================================== 2011AJ....141...28M Erratum: "A Survey of Local Group Galaxies Currently Forming Stars. II. UBVRI Photometry of Stars in Seven Dwarfs and a Comparison of the Entire Sample" (2007, AJ, 133, 2393) Massey, Philip; Olsen, K. A. G.; Hodge, Paul W.; Jacoby, George H.; McNeill, Reagin T.; Smith, R. C.; Strong, Shay B. Abstract. Massey et al. (2006) presented the Local Group Galaxy Survey (LGGS) UBVRI photometry of stars in M31 and M33. These catalogs were reissued with a slight change in the naming convention in Massey et al. (2007, hereafter Paper II), Tables 12 and 13. Last year, Nelson Caldwell (2009, private communication) called our attention to the fact that there appeared to be a slight overabundance of stars in the M31 color-magnitude diagram with a U - B value near 0.00. We established that this came about due to a coding error by the first author in how the photometry from adjacent fields was averaged. The mistake affects only the U - B and R - I values for a small fraction of stars in the M31 and M33 catalogs. These two colors were the only ones affected as stars were required to have V, B - V, and V - R values to be included in the catalog but not U - B and R - I, and the averaging failed for these under certain conditions. In addition, the errors on the V -R colors were found to be underestimated in some cases. These problems affected only the M31 and M33 photometry (Tables 12 and 13) in Paper II, and not the photometry of the seven dwarf galaxies in our sample, as the latter were each observed in a single field rather than in overlapping fields. The printed example tables were also not affected. The online version of the journal contains the revised machine-readable and Virtual Observatory versions of Tables 12 and 13. For M31, the V - R errors were underestimated for 2906 stars out 371,781 (0.8%). The U - B values had to be revised for 13,532 stars out of 192,602 with U - B measurements (7.0%). Of these, only 1025 stars (0.5%) had to be revised by more than 0.05 mag in U - B. For the 329,931 M31 stars with R - I measurements, 4225 values (1.3%) had to be revised, but again only a handful (333, or 0.1%) had significant (>0.05 mag) differences. For M33, the statistics are similarly encouraging. The V - R errors were underestimated for 2696 stars out of 146,622 (1.8%). The U - B values had to be revised for 2244 stars out of 113,058 with U - B measurements (2.0%). Of these, only 783 stars (0.7%) had to be revised by more than 0.05 mag in U - B. For the 133,258 M33 stars with R - I measurements, 3211 values (2.4%) had to be revised, but again only a handful (714, or 0.5%) had significant (>0.05 mag) differences. ===========================================================================
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