Some constraints on the color-magnitude diagram of giants in the galactic spheroid

Abstract

view Abstract Citations (18) References (32) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Some constraints N the color-magnitude diagram of giants in the galactic spheroid. Bahcall, J. N. ; Soneira, R. M. ; Morton, D. C. ; Tritton, K. P. Abstract The color-magnitude diagram of giants in the Galactic spheroid is shown to be important in determining the number-color histogram of stars brighter than B = 19 mag. This result is demonstrated by comparing a standard Galaxy model with observations of 391 stars in a field in the direction of Aquarius (l = 36.5 deg, b = -51.1 deg). More than 80 percent of the spheroid stars and 40 percent of all stars in this magnitude range and direction are predicted to be giants. At most, a few percent of the spheroid stars in the current sample can lie on the main sequence bluer than the turn-off onto the giant branch near B - V approximately 0.4. The available observations suggest that the blue tip of the horizontal branch of the spheroid must be sparsely populated about a factor of 10 less than would be expected if the color-magnitude diagram of the spheroid were the same as diagrams for any of the globular clusters M3, M13, or M92. The total dispersion in colors (measurement errors and intrinsic dispersion) has a standard deviation in B - V color that is less than 0.2 mag. Publication: The Astrophysical Journal Pub Date: September 1983 DOI: 10.1086/161325 Bibcode: 1983ApJ...272..627B Keywords: Color-Magnitude Diagram; Galactic Structure; Giant Stars; Hertzsprung-Russell Diagram; Stellar Color; Stellar Magnitude; Subgiant Stars; Data Acquisition; Histograms; Late Stars; Spheroids; Stellar Structure; Astrophysics full text sources ADS | data products SIMBAD (6)