J/ApJ/736/24 VI photometry of sources in the halo of NGC253 (Bailin+, 2011)
The resolved stellar halo of NGC 253.
Bailin J., Bell E.F., Chappell S.N., Radburn-Smith D.J., de Jong R.S.
<Astrophys. J. 736, 24 (2011)>
=2011ApJ...736...24B 2011ApJ...736...24B
ADC_Keywords: Galaxies, photometry ; Photometry, VRI ; Stars, giant;
Stellar distribution ; HR diagrams
Mission_Name:
Keywords: galaxies: halos - galaxies: individual (NGC 253) -
galaxies: structure - galaxies: formation - galaxies: spiral -
galaxies: starburst
Abstract:
We have obtained Magellan/IMACS and HST/ACS 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 30kpc, 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∼0.35±0.1. The total stellar mass of the halo is estimated to
be M_halo ∼2.5±1.5x109M☉, 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 ~-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.
Description:
Catalog of sources detected in halo field around NGC 253. Observations
were taken at the Magellan/Baade telescope in Bessel V and CTIO I
bands. Sources were found using DAOFIND and aperture photometry was
performed using APPHOT. Photometry has been corrected for extinction
using the NED values for NGC 253.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
starcat.dat 41 91857 Positions and magnitudes of detected stars (table1)
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See also:
J/A+A/450/253 : JHKL photometry of RCW57/NGC3576 (Maercker+, 2006)
J/MNRAS/388/849 : NGC253 XMM observations (Barnard+, 2008)
Byte-by-byte Description of file: starcat.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq Source ID number
7- 8 I2 h RAh Right ascension (J2000.0)
10- 11 I2 min RAm Right ascension (J2000.0)
13- 17 F5.2 s RAs [0/60] Right ascension (J2000.0)
19 A1 --- DE- Declination sign (J2000.0)
20- 21 I2 deg DEd Declination (J2000.0)
23- 24 I2 arcmin DEm Declination (J2000.0)
26- 29 F4.1 arcsec DEs [0/60] Declination (J2000.0)
31- 35 F5.2 mag Vmag Bessel V-band magnitude corrected for
Galactic extinction
37- 41 F5.2 mag Imag CTIO I-band magnitude corrected for
Galactic extinction
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Acknowledgements:
Jeremy Bailin, jbailin(at)umich.edu
(End) Patricia Vannier [CDS] 02-May-2011