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GHOSTS: The Resolved Stellar Outskirts of Massive Disk Galaxies

Published online by Cambridge University Press:  01 December 2006

Roelof S. de Jong
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
A. C. Seth
Affiliation:
CFA
E. F. Bell
Affiliation:
MPIA
T. M. Brown
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
J. S. Bullock
Affiliation:
UC Irvine
S. Courteau
Affiliation:
Queen's Univ.
J. J. Dalcanton
Affiliation:
Univ. of Washington
H. C. Ferguson
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
P. Goudfrooij
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
S. Holfeltz
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
C. Purcell
Affiliation:
UC Irvine
D. Radburn-Smith
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
D. Zucker
Affiliation:
Univ. of Cambridge
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Abstract

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We show initial results from our ongoing HST/ACS GHOSTS survey of the resolved stellar envelopes of 14 nearby, massive disk galaxies. In hierarchical galaxy formation the stellar halos and thick disks of galaxies are formed by accretion of minor satellites and therefore contain valuable information about the (early) assembly process of galaxies. We detect for the first time the very small halo of NGC 4244, a low mass edge-on galaxy. We find that massive galaxies have very extended halos, with equivalent surface brightnesses of 28-29 V-mag arcsec−2 at 20-30 kpc from the disk. The old RGB stars of the thick disk in the NGC 891 and NGC 4244 edge-on galaxies truncate at the same radius as the young thin disk stars, providing insights into the formation of both disk truncations and thick disks. We furthermore present the stellar populations of a very low surface brightness stream around M83, the first such a stream resolved into stars beyond those of the Milky Way and M31.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2007

References

Seth, A., de Jong, R.S., Dalcanton, J. & the GHOSTS team 2007, these proceedings, astro-ph/0701704Google Scholar