Distance to M31 with the Hubble Space Telescope and HIPPARCOS Red Clump Stars
Abstract
Following the approach by Paczyński & Stanek, we compare the red clump stars with parallaxes known to better than 10% in the Hipparcos catalog with the red clump stars observed in three fields in M31 using the Hubble Space Telescope. There are ~600 and ~6300 such stars in the two data sets, respectively. The local red clump luminosity function is well represented by a Gaussian with the peak at MI,m=-0.23 and the dispersion σRC~0.2 mag. This allows a single-step determination of the distance modulus to M31, μ0,M31=24.471+/-0.035+/-0.045 mag (statistical plus systematic error), and the corresponding distance, RM31=784+/-13+/-17 kpc. The number of red clump stars is large enough that the formal statistical error in the distance is only <~2%. We also correct the treatment of the local interstellar extinction by Paczyński & Stanek, and we obtain the Galactocentric distance modulus, μ0,GC=14.57+/-0.04+/-0.04 mag (statistical plus systematic error), and the corresponding Galactocentric distance, R0=8.2+/-0.15+/-0.15 kpc.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 1998
- DOI:
- 10.1086/311539
- arXiv:
- arXiv:astro-ph/9802121
- Bibcode:
- 1998ApJ...503L.131S
- Keywords:
-
- GALAXY: CENTER;
- GALAXIES: INDIVIDUAL MESSIER NUMBER: M31;
- GALAXIES: DISTANCES AND REDSHIFTS;
- SOLAR SYSTEM: GENERAL;
- STARS: HORIZONTAL-BRANCH;
- Galaxies: Distances and Redshifts;
- Galaxies: Individual: Messier Number: M31;
- Galaxy: Center;
- Solar System: General;
- Stars: Horizontal-Branch;
- Astrophysics
- E-Print:
- accepted by the ApJ Letters, 11 pages, 4 figures