CDROM/AJ/V114/P1458 The Carina Dwarf (Mighell 1997) ================================================================================ WFPC2 Observations of the Carina Dwarf Spheroidal Galaxy Kenneth J. Mighell <1997, AJ, 114, 1458> =1997AJ....114.1458M ================================================================================ Abstract: We present our analysis of Hubble Space Telescope Wide Field Planetary Camera 2 observations in F555W (~V) and F814W (~I) of the Carina dwarf spheroidal galaxy. The resulting V vs V-I color-magnitude diagrams reach V ~ 27.1 mag. The reddening of Carina is estimated to be E(V-I) = 0.08 +/- 0.02 mag. A new estimate of the distance modulus of Carina, (m-M)0 = 19.87 +/- 0.11 mag, has been derived primarily from existing photometry in the literature. The apparent distance moduli in V and I were determined to be (m-M)V = 20.05 +/- 0.11 mag and (m-M)I = 19.98 +/- 0.12 mag, respectively. These determinations assumed that Carina has a metallicity of [Fe/H] = -1.9 +/- 0.2 dex. This space-based observation, when combined with previous ground-based observations, is consistent with (but does not necessarily prove) the following star formation scenario. The Carina dwarf spheroidal galaxy formed its old stellar population in a short burst (~< 3 Gyr) at about the same time the Milky Way formed its globular clusters. The dominant burst of intermediate-age star formation then began in the central region of the galaxy where stars formed for several billion years before the process of star formation became efficient enough in the outer regions of the galaxy to allow for the formation of large numbers of stars. There has been negligible star formation during the last few billion years. This observation provides evidence that at least some dwarf galaxies can have complex global star formation histories with local variations of the rate of star formation as a function of time and position within the galaxy. (c) 1997 American Astronomical Society. Description: The FITS ASCII Table version of table2.dat is exactly as supplied by the author. File Summary: -------------------------------------------------------------------------------- File Name Lrecl Records Explanations -------------------------------------------------------------------------------- table2.dat 39 3302 WFPC2 stellar photometry in the Carina dSph galaxy table2.fit 2880 92 FITS ASCII Table version of table2.dat -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1-10 I10 --- ID *Coded indentification 11-18 F8.3 mag V V magnitude 19-25 F7.3 mag e_V rms error of V magnitude 26-32 F7.3 mag V-I (V-I) color 33-39 F7.3 mag e_V-I rms error of (V-I) color -------------------------------------------------------------------------------- Notes for file: table2.dat -------------------------------------------------------------------------------- ID: The left-most digit of the ID gives the WFPC2 chip number where the star may be found (2, 3, or 4). The right-most 4 digits of the ID gives the x coordinate of the star multiplied by 10. The remaining 4 digits gives the y coordinate of the star multiplied by 10. -------------------------------------------------------------------------------- ================================================================================ (End) Lee Brotzman [ADS] 31-Oct-1997