Bibcode
DOI
Lee, Myung Gyoon; Aparicio, Antonio; Tikonov, Nikolay; Byun, Yong-Ik; Kim, Eunhyeuk
Referencia bibliográfica
The Astronomical Journal, Volume 118, Issue 2, pp. 853-861.
Fecha de publicación:
8
1999
Número de citas
48
Número de citas referidas
43
Descripción
We present deep BVI CCD photometry of the stars in the dwarf galaxy DDO
210. The color-magnitude diagrams of DDO 210 show a well-defined red
giant branch (RGB) and a blue plume. The tip of the RGB is found to be
at I_TRGB=20.95+/-0.10 mag. From this, the distance to DDO 210 is
estimated to be d=950+/-50 kpc. The corresponding distance of DDO 210 to
the center of the Local Group is 870 kpc, showing that it is a member of
the Local Group. The mean metallicity of the RGB stars is estimated to
be [Fe/H]=-1.9+/-0.1 dex. Integrated magnitudes of DDO 210 within the
Holmberg radius (r_H=110^''=505 pc) are derived to be M_B=-10.6+/-0.1
and M_V=-10.9+/-0.1 mag. B and V surface brightness profiles of DDO 210
are approximately consistent with an exponential law with scale lengths
r_s(B)=161 and r_s(V)=175 pc. The brightest blue and red stars in DDO
210 (BSG and RSG) are found to be among the faintest in the nearby
galaxies with young stellar populations: _BSG=-3.47+/-0.11 and
_RSG=-4.75+/-0.13 mag. An enhancement of the star formation rate in the
recent past (several hundred Myr) is observed in the central region of
DDO 210. The opposite trend is observed in the outer region of the
galaxy, suggesting a possible two-component structure of the disk/halo
kind found in spiral galaxies. The real nature of this two-component
structure must, however, be confirmed with more detailed observations.