The Halo Stars in NGC 5128. II. An Outer Halo Field and a New Metallicity Distribution

Details The Halo Stars in NGC 5128. II. An Outer Halo Field and a New Metallicity Distribution The Halo Stars in NGC 5128. II. An Outer Halo Field and a New Metallicity Distribution

Nov 2000

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000aj....120.2423h&link_type=abstract

The Astronomical Journal, Volume 120, Issue 5, pp. 2423-2436.

Astronomy and Astrophysics

Astronomy

71

Galaxies: Elliptical And Lenticular, Cd, Galaxies: Evolution, Galaxies: Abundances, Galaxies: Stellar Content, Galaxies: Individual: Ngc Number: Ngc 5128

Scientific paper

We present new Hubble Space Telescope WFPC2 (V, I) photometry for stars in NGC 5128 at a projected distance more than 30 kpc from the galaxy center. The color-magnitude diagram shows an old red-giant branch which is extremely broad in color, identical in its characteristics with our previously observed 20 kpc halo field (Harris et al.). To derive the metallicity distribution function (MDF) from the red giant color distribution, we use an extensive new grid of low-mass stellar models (VandenBerg et al.) calibrated against Milky Way globular clusters, along with a new interpolation procedure. We find that the halo of NGC 5128 is predominantly populated by moderately metal-rich stars in the range -1.0<[m/H]<0.0. The mean abundance is =0.37 Zsolar (=-0.43) with no detectable radial gradients. Since only 10% of the stars are more metal-poor than [m/H]~=-1, the MDF places severe restrictions on the fraction of the halo that could have been accreted from dwarf elliptical or small disk galaxies. A first-order chemical enrichment model which fits our observed MDF remarkably well is one in which the galaxy experienced two fairly distinct stages of halo formation: a very early ``accreting-box'' stage starting from primordial gas in which stars are already forming while the galaxy is still assembling by gas infall; and a second, more major stage of ``closed-box'' evolution dominated by star formation with little gas infall.

Affiliated with

Also associated with

No associations

Rating

The Halo Stars in NGC 5128. II. An Outer Halo Field and a New Metallicity Distribution 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 The Halo Stars in NGC 5128. II. An Outer Halo Field and a New Metallicity Distribution, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Halo Stars in NGC 5128. II. An Outer Halo Field and a New Metallicity Distribution will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1148004