NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-05-23 T04:02:30 PDT
Help | Comment | NED Home

For refcode 1996AJ....112..948W:
Retrieve 4 NED objects in this reference.
Please click here for ADS abstract

NED Abstract

Copyright by American Astronomical Society. Reproduced by permission
1996AJ....112..948W THE G DWARF PROBLEM EXISTS IN OTHER GALAXIES GUY WORTHEY Department of Astronomy, University of Michigan, Ann Arbor, Michigan 48109-1090 Electronic mail: worthey@astro.lsa.umich.edu BEN DORMAN Laboratory for Astronomy & Solar Physics, NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771 Electronic mall: dorman@shemesh.gsfc.nasa.gov LEWIS A. JONES Department of Physics and Astronomy, University of North Carolina, CB#3255 Phillips Hall, Chapel Hill, North Carolina 27599-3255 Electronic mail: lewis@physics.unc.edu Received 1996 May 3; revised 1996 June 4 ABSTRACT Stellar population models with abundance distributions determined from the analytic Simple model of chemical evolution fail to match observations of the nuclei of bulge-dominated galaxies in three respects. First, the spectral energy distribution in the mid-ultraviolet range 200O < {lambda} < 2400 A exceeds observation by ~0.6 mag. Most of that excess is due to metal-poor main sequence stars. Second, the models do not reproduce metal-sensitive optical absorption features that arise mainly from red giant stars. Third, the strength of a Ca II index sensitive to hot stars does not jibe with the predicted number of A-type horizontal branch stars. The number of metal-poor stars in galaxies is at least a factor of 2 less than predicted by the Simple model, exactly similar to the "G dwarf problem" in the solar cylinder. Observations at larger radii in local group galaxies indicate that the paucity of metal- poor stars applies globally, rather than only in the nuclei. Because of the dominance of metal-rich stars, primordial galaxies will have a plentiful dust supply early in their star formation history, and thus will probably have weak Ly{alpha} emission, as is apparently observed. We confirm that early-type galaxies cannot have been formed exclusively from mergers of small all-stellar subsystems, a result already established by dynamical simulations. The constraint of peaked abundance distributions will limit future chemical evolution models. It will also make age estimates for the stellar populations in early-type galaxies and bulges more secure.
Retrieve 4 NED objects in this reference.
Please click here for ADS abstract

Back to NED Home