2001AJ....121.3007S -
Astron. J., 121, 3007-3025 (2001/June-0)
A near-infrared stellar census of blue compact dwarf galaxies: the Wolf-Rayet galaxy I Zw 36.
SCHULTE-LADBECK R.E., HOPP U., GREGGIO L., CRONE M.M. and DROZDOVSKY I.O.
Abstract (from CDS):
We report the results of near-IR imaging in J and H, of I Zw 36 (~Z☉/14) with the Hubble Space Telescope. Whereas imaging with the pre-COSTAR Faint Object Camera (FOC) previously resolved hot and massive stars in the near-UV, the NICMOS data furnish a census of the cool, intermediate- and low-mass stars. There clearly was star formation in I Zw 36 prior to the activity which earned it its blue compact dwarf/Wolf-Rayet galaxy classification. The detection of luminous, asymptotic giant branch stars requires that stars formed vigorously several hundred megayears ago. The well-populated red giant branch indicates stars with ages of at least 1-2 Gyr (and possibly older than 10 Gyr). We use the tip-of-the-red-giant-branch method to derive a distance of ≥5.8 Mpc. This is the third in a series of papers on near-IR-resolved blue compact dwarf galaxies. We notice that the color-magnitude diagrams of VII Zw 403, Mrk 178, and I Zw 36 do not exhibit the gaps expected from an episodic mode of star formation. Using simulated color-magnitude diagrams we demonstrate for I Zw 36 that star formation did not stop for more than a few 108 yr over the past 109 yr, and we discuss the implications of this result.
Abstract Copyright:
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Journal keyword(s):
Galaxies: Dwarf - Galaxies: Evolution - galaxies: individual (I Zw 36) - Galaxies: Stellar Content - Stars: Wolf-Rayet
Simbad objects:
12
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