NGC 188, the age of the galactic disk, and the evolution of the Li abundance

Journal Article · Wed Mar 01 04:00:00 EST 1989 · Astron. J.; (United States)

DOI:https://doi.org/10.1086/115020· OSTI ID:6068878

Twarog, B A; Anthony-Twarog, B J

The implications of an age for the open cluster NGC 188 only slightly larger than that of M67 are investigated. It is demonstrated that a differential and absolute comparison of the cluster color-magnitude diagrams leads to no inconsistencies if the reddening for NGC 188 is 0.09 mag larger than that for M67, while the apparent modulus of NGC 188 is 1.8 mag larger. Assuming E(B-V) = 0.03 and (m-M) = 9.7 for M67 results in an age of approximately 5 billion yr for M67 and 6.5 billion yr for NGC 188. The shift required by the differential reddening and distance modulus also removes the Li anomaly recently found by Hobbs and Pilachowski (1988) for NGC 188. If the metallicity of NGC 188 is significantly higher than that of M67, the required reddening differential would be smaller for the same age difference. A younger age for NGC 188 produces no inconsistencies with current theories of stellar and Galactic evolution, and may actually be more consistent than an age similar to the metal-rich globular cluster 47 Tucanae. 55 references.

• Research Organization: Kansas Univ., Lawrence (USA)
• OSTI ID: 6068878
• Journal Information: Astron. J.; (United States), Journal Name: Astron. J.; (United States) Vol. 97; 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
ABUNDANCE
AGE ESTIMATION
ALKALI METALS
CHEMICAL COMPOSITION
COMPARATIVE EVALUATIONS
ELEMENTS
GALACTIC EVOLUTION
GALAXIES
LITHIUM
METALS
MILKY WAY
RED SHIFT
STAR CLUSTERS