The stellar populations of M 33
- Dominion Astrophysical Observatory, Victoria (Canada)
A review is given of present ideas on the evolution and stellar content of the Triangulum nebula = M 33 = NGC 598. The disk of M 33 is embedded in a halo of globular clusters, metal-poor red giants, and RR Lyrae stars. Its nuclear bulge component is weak, suggesting that the halos of galaxies are not extensions of their bulges to large radii. The ages of M 33 clusters do not appear to exhibit a hiatus in their star-forming history like that which is observed in the Large Magellanic Cloud (LMC). Young and intermediate-age clusters with luminosities rivaling the populous clusters in the LMC are rare in M 33. The integrated light of the semistellar nucleus of M 33, which contains the strongest X-ray source in the Local Group, is dominated by a young metal-rich population. At optical wavelengths the disk scale length of M 33 is 9.6 arcmin, which is similar to the 9.9 arcmin scale length of OB associations. The ratio of the nova rate in M 33 to that in M 31 is approximately equal to the ratio of their luminosities. This suggests that the nova rate in a galaxy is not determined entirely by the integrated luminosity of old bulge stars. The gas-depletion time scale in the central region of M 33 is found to be about 1.7 {times} 10 to the 9th yr, which is significantly shorter than a Hubble time. 141 refs.
- OSTI ID:
- 5183224
- Journal Information:
- Publications of the Astronomical Society of the Pacific; (United States), Vol. 103; ISSN 0004-6280
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
GALACTIC EVOLUTION
GALAXIES
POPULATIONS
AGE ESTIMATION
CEPHEIDS
COSMIC X-RAY SOURCES
GALAXY NUCLEI
MORPHOLOGY
NEBULAE
NOVAE
SPATIAL DISTRIBUTION
SPIRAL CONFIGURATION
STAR CLUSTERS
STAR EVOLUTION
CONFIGURATION
COSMIC RAY SOURCES
DISTRIBUTION
ERUPTIVE VARIABLE STARS
PULSATING VARIABLE STARS
STARS
VARIABLE STARS
640105* - Astrophysics & Cosmology- Galaxies