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2000A&A...361..929M - Astronomy and Astrophysics, volume 361, 929-936 (2000/9-3)

New color-magnitude diagram for the open cluster IC 4651. Deep Stroemgren uvby CCD photometry in a large field.

MEIBOM S.

Abstract (from CDS):

New accurate CCD photometry in the u, v, b and y bands of the Stroemgren system filters has been obtained for 17640 stars to V∼20m in a ∼21'x21' field centered on the intermediate-age open cluster IC 4651. The resulting color-magnitude diagram (CMD) is substantially improved in completeness and accuracy compared to previous studies of IC 4651. Specifically, this study has: 1) more than doubled the known size of the cluster area on the sky, 2) more than doubled the number of stars brighter than V∼14m, 3) added 160 new" candidate member stars to the turn-off region of the CMD, 4) identified ∼600 fainter stars that trace a previously undetected and well-defined main-sequence down to V∼18m, and 5) enabled a very accurate determination of true distance modulus ((m-M)0=10.03±0.1) by fitting the Hyades main-sequence over the long stretch of the cluster main-sequence. The (v-y)-V CMD defines the main-sequence significantly better than the traditional (b-y) or (B-V) CMDs. These findings make IC 4651 a perfect target for testing stellar evolution models. A correlation is found between the CMD and the radial distance of the stars to the cluster center. The fainter main-sequence stars are less centrally concentrated, as predicted by theory. Overall, IC 4651 appears to be a moderately dynamically evolved cluster ideally suited for testing of dynamical models.

Journal keyword(s): Galaxy: open clusters and associations: individual: IC 4651 - stars: Hertzsprung-Russel (HR) and C-M diagrams

VizieR on-line data: <Available at CDS (J/A+A/361/929): table1 table2 table3>

Nomenclature: Table 2: Cl* IC 4651 MEI NNNNN (Nos 1-17640).

Status at CDS : All or part of tables of objects will not be ingested in SIMBAD.