Stellar content of nearby galaxies. III. The local group spiral galaxy M33

Journal Article · Mon Jan 01 04:00:00 EST 1990 · Astronomical Journal; (USA)

DOI:https://doi.org/10.1086/115317· OSTI ID:6863329

Wilson, C D; Madore, B F; Freedman, W L ^[1]

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1. California Institute of Technology, Pasadena (USA) Mount Wilson and Las Campanas Observatories, Pasadena, CA (USA)

BVRI CCD photometry is presented for stars brighter than V = 21 mag in four fields in the nearby spiral galaxy M33. V vs (B - V) and I vs (V - I) color-magnitude diagrams clearly show both a young stellar population (as indicated by the blue main sequence and red supergiant plumes) as well as an intermediate-age population of asymptotic giant branch stars. Deep photometry in the outer field (where crowding is less severe) reveals a population consistent in color and magnitude with the tip of the first red giant branch. The M33 distance modulus, 24.6 + or - 0.3 mag, derived from this Population II component is consistent with a recent redetermination of the distance modulus found from Population I Cepheid variables. Finally, some evidence is presented for a radial gradient in the average internal reddening for the fields in M33 reported here. 30 refs.

• OSTI ID: 6863329
• Journal Information: Astronomical Journal; (USA), Journal Name: Astronomical Journal; (USA) Vol. 99; ISSN 0004-6256; ISSN ANJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BRIGHTNESS
CHARGE-COUPLED DEVICES
CONFIGURATION
DISTANCE
GALAXIES
GIANT STARS
MAIN SEQUENCE STARS
OPTICAL PROPERTIES
PHOTOMETRY
PHYSICAL PROPERTIES
POPULATIONS
RED GIANT STARS
SEMICONDUCTOR DEVICES
SPIRAL CONFIGURATION
STARS
SUPERGIANT STARS