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Title: THE RESOLVED STELLAR HALO OF NGC 253

Abstract

We have obtained Magellan/IMACS and Hubble Space Telescope (HST)/Advanced Camera for Surveys imaging data that resolve red giant branch stars in the stellar halo of the starburst galaxy NGC 253. The HST data cover a small area, and allow us to accurately interpret the ground-based data, which cover 30% of the halo to a distance of 30 kpc, allowing us to make detailed quantitative measurements of the global properties and structure of a stellar halo outside of the Local Group. The geometry of the halo is significantly flattened in the same sense as the disk, with a projected axis ratio of b/a {approx} 0.35 {+-} 0.1. The total stellar mass of the halo is estimated to be M{sub halo} {approx} (2.5 {+-} 1.5) x 10{sup 9} M{sub sun}, or 6% of the total stellar mass of the galaxy, and has a projected radial dependence that follows a power law of index -2.8 {+-} 0.6, corresponding to a three-dimensional power-law index of {approx} - 4. The total luminosity and profile shape that we measure for NGC 253 are somewhat larger and steeper than the equivalent values for the Milky Way and M31, but are well within the scatter of model predictionsmore » for the properties of stellar halos built up in a cosmological context. Structure within the halo is seen at a variety of scales: there is small kpc-scale density variation and a large shelf-like feature near the middle of the field. The techniques that have been developed will be essential for quantitatively comparing our upcoming larger sample of observed stellar halos to models of halo formation.« less

Authors:
; ;  [1];  [2];  [3]
  1. Department of Astronomy, University of Michigan, 830 Dennison Building, 500 Church Street, Ann Arbor, MI 48109 (United States)
  2. Department of Astronomy, University of Washington, Seattle, WA 98195 (United States)
  3. Leibniz-Institut fuer Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany)
Publication Date:
OSTI Identifier:
21578342
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 736; Journal Issue: 1; Other Information: DOI: 10.1088/0004-637X/736/1/24; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; GALAXIES; GIANT STARS; LUMINOSITY; MASS; OPTICAL PROPERTIES; PHYSICAL PROPERTIES; STARS

Citation Formats

Bailin, Jeremy, Bell, Eric F., Chappell, Samantha N., Radburn-Smith, David J., and De Jong, Roelof S., E-mail: jbailin@umich.edu. THE RESOLVED STELLAR HALO OF NGC 253. United States: N. p., 2011. Web. doi:10.1088/0004-637X/736/1/24.
Bailin, Jeremy, Bell, Eric F., Chappell, Samantha N., Radburn-Smith, David J., & De Jong, Roelof S., E-mail: jbailin@umich.edu. THE RESOLVED STELLAR HALO OF NGC 253. United States. doi:10.1088/0004-637X/736/1/24.
Bailin, Jeremy, Bell, Eric F., Chappell, Samantha N., Radburn-Smith, David J., and De Jong, Roelof S., E-mail: jbailin@umich.edu. Wed . "THE RESOLVED STELLAR HALO OF NGC 253". United States. doi:10.1088/0004-637X/736/1/24.
@article{osti_21578342,
title = {THE RESOLVED STELLAR HALO OF NGC 253},
author = {Bailin, Jeremy and Bell, Eric F. and Chappell, Samantha N. and Radburn-Smith, David J. and De Jong, Roelof S., E-mail: jbailin@umich.edu},
abstractNote = {We have obtained Magellan/IMACS and Hubble Space Telescope (HST)/Advanced Camera for Surveys imaging data that resolve red giant branch stars in the stellar halo of the starburst galaxy NGC 253. The HST data cover a small area, and allow us to accurately interpret the ground-based data, which cover 30% of the halo to a distance of 30 kpc, allowing us to make detailed quantitative measurements of the global properties and structure of a stellar halo outside of the Local Group. The geometry of the halo is significantly flattened in the same sense as the disk, with a projected axis ratio of b/a {approx} 0.35 {+-} 0.1. The total stellar mass of the halo is estimated to be M{sub halo} {approx} (2.5 {+-} 1.5) x 10{sup 9} M{sub sun}, or 6% of the total stellar mass of the galaxy, and has a projected radial dependence that follows a power law of index -2.8 {+-} 0.6, corresponding to a three-dimensional power-law index of {approx} - 4. The total luminosity and profile shape that we measure for NGC 253 are somewhat larger and steeper than the equivalent values for the Milky Way and M31, but are well within the scatter of model predictions for the properties of stellar halos built up in a cosmological context. Structure within the halo is seen at a variety of scales: there is small kpc-scale density variation and a large shelf-like feature near the middle of the field. The techniques that have been developed will be essential for quantitatively comparing our upcoming larger sample of observed stellar halos to models of halo formation.},
doi = {10.1088/0004-637X/736/1/24},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 736,
place = {United States},
year = {2011},
month = {7}
}