The age of the globular cluster NGC 288, the formation of the Galactic halo, and the second parameter

Journal Article · Thu Jun 01 04:00:00 EDT 1989 · Astronomical Journal; (USA)

DOI:https://doi.org/10.1086/115106· OSTI ID:5470067

Bolte, M ^[1]

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1. Dominion Astrophysical Observatory, Victoria (Canada)

A differential comparison of precise CCD photometry in the globular clusters NGC 288, NGC 362, and NGC 1261 shows that differences exist in the positions of the main-sequence turnoff in these clusters that are most naturally explained if NGC 288 is some 3 billion yr older than NGC 362 and about 1 to 2 billion yr older than NGC 1261. This implies that the formation time for the Galactic halo is significantly longer than a freefall time. Consideration of the inferred ages and horizontal-branch morphologies of the clusters Pal 12, NGC 288, NGC 362, and NGC 1261, all with similar metal abundances, suggests that age may be the parameter that, after overall metal abundance, most determines horizontal-branch morphology. 56 refs.

• OSTI ID: 5470067
• Journal Information: Astronomical Journal; (USA), Journal Name: Astronomical Journal; (USA) Vol. 97; ISSN 0004-6256; ISSN ANJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
640105 -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
AGE ESTIMATION
CHARGE-COUPLED DEVICES
CHEMICAL COMPOSITION
GALACTIC EVOLUTION
GALAXIES
MILKY WAY
MORPHOLOGY
PHOTOMETRY
SEMICONDUCTOR DEVICES
STAR CLUSTERS
STAR EVOLUTION