CCD photometry of stars in the old open cluster NGC 188

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

DOI:https://doi.org/10.1086/115325· OSTI ID:6598336

Caputo, F; Chieffi, A; Castellani, V; Collados, M; Martinez Roger, C ^[1]

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1. CNR, Istituto di Astrofisica Spaziale, Frascati (Italy) Osservatorio di Collurania, Teramo (Italy) Instituto de Astrofisica de Canarias, La Laguna (Spain)

CCD photometry for stars in three fields centered on the old open cluster NGC 188 is presented, with the aim of investigating the HR diagram distribution of cluster main-sequence stars. A sequence of subgiant, turnoff, and main-sequence stars has been detected, extending the observed lower main sequence down to about m(v) = 20 mag. It is found that the observed color-magnitude diagram appears well fitted by a theoretical isochrone for an age of about 6-billion yr, provided that Yale transformations from the theoretical into the observational plane are assumed. From the distribution of the stellar luminosities, it is found that the turnoff stars should have masses of about 1.3 solar mass. The cluster evolutionary scenario is discussed in connection with the reported luminosity of the clump of He-burning giants. 21 refs.

• OSTI ID: 6598336
• 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

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AGE ESTIMATION
CHARGE-COUPLED DEVICES
DIAGRAMS
GIANT STARS
HELIUM BURNING
HERTZSPRUNG-RUSSELL DIAGRAM
LUMINOSITY
MAIN SEQUENCE STARS
MASS
OPTICAL PROPERTIES
PHOTOMETRY
PHYSICAL PROPERTIES
SEMICONDUCTOR DEVICES
STAR BURNING
STAR CLUSTERS
STAR EVOLUTION
STARS