STELLAR POPULATIONS OF THE DWARF GALAXY LGS-3 IN THE LOCAL GROUP

被引:40
作者
LEE, MG
机构
[1] Department of Astronomy, Seoul National University
关键词
D O I
10.1086/117592
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present VRI CCD photometry of similar to 490 stars in the dwarf galaxy LGS 3 in the Local Group. The color-magnitude diagrams of LGS 3 show a well defined red giant branch (RGB), a small number of asymptotic giant branch stars, and several blue stars which are possibly young main-sequence stars. The tip of the RGB is found to be at I-TRGB=20.6+/-0.2 mag and (V-I)(TRGB)=1.31+/-0.05 mag. From the I magnitude of the tip of the RGB, we estimate the distance modulus of LGS 3 to be (m - M)(0)=24.54+/-0.21 mag for an adopted extinction of A(V)=0.08 mag, corresponding to a distance of 810+/-80 kpc. This result shows that LGS 3 may be a satellite of M31 or M33 which are close to LGS 3 in the sky. We measure the mean color of the RGB at M(I)=-3.5 mag (similar to 0.5 mag fainter than the tip of the RGB) to be (V-I)(-3.5)=1.28+/-0.05 mag. From these values we estimate the mean metallicity of the RGB stars to be [Fe/H]=-2.10+/-0.22 dex. The integrated magnitudes of LGS 3 within the aperture radius r=106'' are measured to be V=14.26 mag, R=13.84 mag, and I=13.26 mag. The absolute integrated magnitude of LGS 3 is derived to be M(V)=-10.35 mag. The central surface brightness is measured to be mu(V)(0)=24.8+/-0.07 mag arcsec(-2). Surface brightness profiles and star number density profiles based on star counts are well fitted by a King model with a core concentration parameter c=log(r(t)/r(c))=1.25+/-0.13, where r(t) and r(c) represents the tidal radius and the core radius, respectively. The core radius is measured to be r(c)=49''+/-3'', corresponding to 190+/-10 pc. The metallicity and the absolute magnitude of LGS 3 are consistent with the metallicity-luminosity relation for the dwarf spheroidal galaxies in the Local Group. (C) 1995 American Astronomical Society.
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页码:1129 / 1140
页数:12
相关论文
共 39 条
[1]   REDDENING ESTIMATES FOR GALAXIES IN THE 2ND REFERENCE CATALOG AND THE UPPSALA GENERAL CATALOG [J].
BURSTEIN, D ;
HEILES, C .
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 1984, 54 (01) :33-79
[2]   THE DWARF SPHEROIDAL COMPANIONS TO M31 - SURFACE-BRIGHTNESS PROFILES [J].
CALDWELL, N ;
ARMANDROFF, TE ;
SEITZER, P ;
DACOSTA, GS .
ASTRONOMICAL JOURNAL, 1992, 103 (03) :840-&
[3]  
CARIGNAN C, 1992, APJ, V381, pL13
[4]   VIDEO CAMERA CCD STANDARD STARS (KPNO VIDEO CAMERA CCD STANDARDS CONSORTIUM) [J].
CHRISTIAN, CA ;
ADAMS, M ;
BARNES, JV ;
BUTCHER, H ;
HAYES, DS ;
MOULD, JR ;
SIEGEL, M .
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC, 1985, 97 (590) :363-372
[5]   THE LOCAL GROUP IRREGULAR GALAXIES LGS-3 AND PEGASUS [J].
CHRISTIAN, CA ;
TULLY, RB .
ASTRONOMICAL JOURNAL, 1983, 88 (07) :934-938
[6]  
COOK KH, 1989, BAAS, V21, P775
[7]   STANDARD GLOBULAR-CLUSTER GIANT BRANCHES IN THE (MI,(V-I)O) PLANE [J].
DACOSTA, GS ;
ARMANDROFF, TE .
ASTRONOMICAL JOURNAL, 1990, 100 (01) :162-181
[8]  
DAVIS L, 1990, COMMUNICATION
[9]   DEEP CCD PHOTOMETRY OF THE DWARF SPHEROIDAL GALAXY LEO-II [J].
DEMERS, S ;
IRWIN, MJ .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1993, 261 (03) :657-673
[10]   LARGE-SCALE PHOTOGRAPHIC SURVEY OF FORNAX [J].
DEMERS, S ;
IRWIN, MJ ;
KUNKEL, WE .
ASTRONOMICAL JOURNAL, 1994, 108 (05) :1648-1657