Computer Science
Scientific paper
Jul 2006
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006hst..prop10794g&link_type=abstract
HST Proposal ID #10794. Cycle 15
Computer Science
Scientific paper
Dwarf elliptical dE galaxies form some of the most numerous galaxies in the universe, yet their origins remain a mystery. The most popular formation scenarios are that dEs are either ancient, primordial objects, or the recent remnants of disrupted progenitor galaxies. These scenarios predict significantly different ratios of old and intermediate age stars. Stellar population characteristics can therefore discriminate between these scenarios. Previous spectroscopic work based on line strengths has had too many uncertainties to uniquely infer the stellar populations. Resolved color magnitude diagrams are needed instead. Since dE galaxies generally do not have stars younger than 1 Gyr, resolving the main sequence turnoff is required to directly quantify the star formation histories. Only ACS on HST can reach this depth, and it can only do so for the nearest two dE galaxies in the Local Group: the M31 dE satellites NGC 147 and NGC 185. Their main sequence turnoffs are expected to be at an apparent magnitude of V=29; we request F606W/F814W imaging one half magnitude fainter than this limit and more than four magnitudes fainter than the deepest previous dE observations. This will quantify the ratio of old to intermediate-age stars and will allow us to discriminate between the competing models of dE formation. On-going Keck/DEIMOS spectroscopy of several hundred red giant stars in each of these two dE galaxies, coupled with dynamical modeling and spectral synthesis, will complement the ACS measurement by providing information on chemical abundance patterns, dark matter content and internal dynamics. The proposed ACS data will be the first to directly quantify the onset and duration of star formation episodes in any dE galaxy. This measurement can only be done with HST/ACS, and it can only be done for these two galaxies in the dE class. This project will therefore be unique, and will be the most comprehensive study to date of any dE galaxy.
No associations
LandOfFree
Direct Age Determination of the dE Galaxies NGC 147 and NGC 185 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 Direct Age Determination of the dE Galaxies NGC 147 and NGC 185, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Direct Age Determination of the dE Galaxies NGC 147 and NGC 185 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1792354