Abstract / Description of output
We use data from the Isaac Newton Telescope Wide-Field Camera survey of
M31 to determine the surface brightness profile of M31 along the
southeast minor axis. We combine surface photometry and faint red giant
branch star counts to trace the profile from the innermost regions out
to a projected radius of 4° (~55 kpc), where μV~32 mag
arcsec-2 this is the first time the M31 minor-axis profile
has been mapped over such a large radial distance using a single data
set. We confirm the finding by Pritchet & van den Bergh that the
minor-axis profile can be described by a single de Vaucouleurs law out
to a projected radius of 1.4d or ~20 kpc. Beyond this, the surface
brightness profile flattens considerably and is consistent with either a
power law of index about -2.3 or an exponential of scale length 14 kpc.
The fraction of the total M31 luminosity contained in this component is
~2.5%. While it is tempting to associate this outer component with a
true Population II halo in M31, we find that the mean color of the
stellar population remains roughly constant at V-i~1.6 from 0.5d to 3.5d
along the minor axis. This result suggests that the same metal-rich
stellar population dominates both structural components.
Based on observations made with the Isaac Newton Telescope operated on
the island of La Palma by the Isaac Newton Group in the Spanish
Observatorio del Roque de los Muchachos of the Instituto de
Astrofísica de Canarias.
Original language | English |
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Journal | Astrophysical Journal |
Volume | 628 |
Issue number | 2 |
DOIs | |
Publication status | Published - 1 Aug 2005 |
Keywords / Materials (for Non-textual outputs)
- Galaxies: Evolution
- Galaxies: Halos
- Galaxies: Individual: Messier Number: M31
- Galaxies: Stellar Content
- Galaxies: Structure
- Galaxies: Local Group