Gclusters :: Bibliographic item "gc383"

Release 11.12 ("Hergest Ridge")

Gclusters :: Bibliographic item "gc383"

Article ID: gc383

Author Schade, David; Vandenberg, Don A.; Hartwick, F. D. A.

Title A color-magnitude diagram for the halo globular cluster M55
Journal Astronomical Journal, vol. 96, p. 1632-1641
Year of publication 1988 (on gclusters from 2013-10-11 17:05:52 )

Abstract The authors present new CCD photometry for the globular cluster M55 that extends well below the main-sequence turnoff. Combining these new data with previously published photographic photometry of cluster giants and horizontal-branch stars yields a high-quality composite color-magnitude diagram (CMD). A comparison of the latter with recent CMDs for M68 and NGC 6752 - two clusters whose metallicities bracket that of M55 - suggests (1) that the reddening to M55 may be as high as E(B-V) = 0.14 mag, and (2) that all three systems have similar ages. In particular, if the apparent distance modulus to M55 is (m-M)V = 14.10 mag, then isochrones for Y = 0.24 and high [O/Fe] would suggest an age of around 14 Gyr. Very encouraging agreement of the observations with theoretical predictions is found.

Tags NGC 6809
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Article ID: gc383
Author	Schade, David; Vandenberg, Don A.; Hartwick, F. D. A.
Title	A color-magnitude diagram for the halo globular cluster M55
Journal	Astronomical Journal, vol. 96, p. 1632-1641
Year of publication	1988 (on gclusters from 2013-10-11 17:05:52 )
Abstract	The authors present new CCD photometry for the globular cluster M55 that extends well below the main-sequence turnoff. Combining these new data with previously published photographic photometry of cluster giants and horizontal-branch stars yields a high-quality composite color-magnitude diagram (CMD). A comparison of the latter with recent CMDs for M68 and NGC 6752 - two clusters whose metallicities bracket that of M55 - suggests (1) that the reddening to M55 may be as high as E(B-V) = 0.14 mag, and (2) that all three systems have similar ages. In particular, if the apparent distance modulus to M55 is (m-M)V = 14.10 mag, then isochrones for Y = 0.24 and high [O/Fe] would suggest an age of around 14 Gyr. Very encouraging agreement of the observations with theoretical predictions is found.
Tags	NGC 6809