Astronomy and Astrophysics – Astrophysics
Scientific paper
1997-09-25
Astronomy and Astrophysics
Astrophysics
16 pages, AASTeX, 9 postscript figures, figures 1 and 2 available at ftp://bb3.jpl.nasa.gov/pub/draco/. Accepted for publicati
Scientific paper
10.1086/300169
We present an F606W-F814W color-magnitude diagram for the Draco dwarf spheroidal galaxy based on Hubble Space Telescope WFPC2 images. The luminosity function is well-sampled to 3 magnitudes below the turn-off. We see no evidence for multiple turnoffs and conclude that, at least over the field of the view of the WFPC2, star formation was primarily single-epoch. If the observed number of blue stragglers is due to extended star formation, then roughly 6% (upper limit) of the stars could be half as old as the bulk of the galaxy. The color difference between the red giant branch and the turnoff is consistent with an old population and is very similar to that observed in the old, metal-poor Galactic globular clusters M68 and M92. Despite its red horizontal branch, Draco appears to be older than M68 and M92 by 1.6 +/- 2.5 Gyrs, lending support to the argument that the ``second parameter'' which governs horizontal branch morphology must be something other than age. Draco's observed luminosity function is very similar to that of M68, and the derived initial mass function is consistent with that of the solar neighborhood.
Ballester Gilda E.
Burrows Chistopher J.
Clarke John T.
Crisp Dave
Evans Robert W.
No associations
LandOfFree
Hubble Space Telescope Observations of the Draco Dwarf Spheroidal does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Hubble Space Telescope Observations of the Draco Dwarf Spheroidal, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hubble Space Telescope Observations of the Draco Dwarf Spheroidal will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-201501