2003/08/26 by Myung Goon Lee, Lee, Myung Goon, Hong Soo Park +32
Physics and Astronomy · #Adaptive optics and wavefront sensing #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0308469
36 pages, 23 figures (15 postscript, 1 jpg and 7 gif), To appear in the Astronomical Journal, 2003 December issue
openalex publication_date 2003/08/26 · arxiv created 2003/08/27 · arxiv updated 2009/12/01 · openalex created_date 2022/10/01 · openalex updated_date 2026/07/28
We present deep wide field VI CCD photometry of the Sextans dwarf\nspheroidal galaxy (dSph) in the Local Group, covering a field of 42' x 28'\nlocated at the center of the galaxy. Color-magnitude diagrams of the Sextans\ndSph show well-defined red giant branch (RGB), blue horizontal branch (BHB),\nprominent red horizontal branch (RHB), asymptotic giant branch (AGB), about 120\nvariable star candidates including RR Lyraes and anomalous Cepheids, about 230\nblue stragglers (BSs), and main sequence (MS) stars. The distance to the galaxy\nis derived using the I-band magnitude of the tip of the RGB at\nI(TRGB)=15.95+/-0.04: (m-M)0=19.90+/-0.06 for an adopted reddening of\nE(B-V)=0.01. The mean metallicity of the RGB is estimated from the (V-I) color:\n[Fe/H]=-2.1+/-0.1(statistical error) +/-0.2(standard calibration error) dex,\nwith a dispersion of sigma[Fe/H]=0.2 dex. The age of the MSTO of the main old\npopulation is estimated to be similar to that of M92, and there are seen some\nstellar populations with younger age. There is found to be one RGB bump at\nV=19.95+/-0.05 mag (MV=0.03 mag), and a weak brighter bump at V=19.35+/-0.05\nmag(Mv=-0.58 mag) which is probably an AGB bump. The V-band luminosity function\nof the RGB and MS stars is in general similar to that of M92, with a slight\nexcess of stars in the magnitude range brighter than the MSTO with respect to\nthat of M92. The bright BSs are more centrally concentrated than the faint BSs.\nSignificant radial gradients are seen for several kinds of populations: the\nRHB, the red RGB, the red subgiant branch (SGB), and the bright BSs are more\ncentrally concentrated toward the center of the galaxy, compared with the BHB,\nthe blue RGB, the blue SGB, and the faint BSs, respectively.\n