The halo and disk populations of M31

Abstract

view Abstract Citations (20) References (38) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The halo and disk populations of M 31. Crotts, A. P. S. Abstract Two-color photometry of a sample of stars effectively complete to Thuan-Gunn (1976) g = 24 and with information to r = 25.5 is presented for selected regions in the outer part of M31. The field positions are chosen so that the color-magnitude distributions can then be compared to yield the properties of the disk and halo as separate populations. The halo contains a strong component falling near the color-magnitude locus of the red giant branch of M92, an old, metal-poor globular cluster. The disk population 18 kpc from the center contains components with a mixture of ages and compositions not separated using the red giant branch alone, but it does contain a component with main-sequence lifetimes as short as 10 to the 8th yr. A count-brightness ratio study of the same data yields consistent results. In one field far from the visible disk, a population younger or metal enriched with respect to the halo is detected, including some stars at the locus of the horizontal branch. This indicates that some populations far from the disk show properties different from those of the halo, and their presence there may be the product of distortion of the outer disk instead. Publication: The Astronomical Journal Pub Date: August 1986 DOI: 10.1086/114160 Bibcode: 1986AJ.....92..292C Keywords: Andromeda Galaxy; Disk Galaxies; Halos; Metallicity; Red Giant Stars; Stellar Spectrophotometry; Color-Magnitude Diagram; Error Analysis; Globular Clusters; Stellar Luminosity; Astrophysics full text sources ADS | data products SIMBAD (4) NED (1)