Bibcode
Sarajedini, Ata; Anderson, J.; Aparicio, A.; Bedin, L.; Chaboyer, B.; Dotter, A.; Hempel, M.; King, I. R.; Majewski, S. R.; Marin-Franch, A.; Milone, A.; Paust, N. E.; Piotto, G.; Reid, I. N.; Rosenberg, A.; Siegel, M.
Bibliographical reference
2007 AAS/AAPT Joint Meeting, American Astronomical Society Meeting 209, #100.09; Bulletin of the American Astronomical Society, Vol. 38, p.1044
Advertised on:
12
2006
Citations
1
Refereed citations
1
Description
The HST/ACS Survey of Galactic globular clusters is a Treasury project
designed to obtain photometry with S/N ≥10 for main sequence stars
with masses ≥ 0.2M&sun; in a large sample of globulars
using the Advanced Camera for Surveys (ACS) Wide Field Channel. We plan
to use these data to address a range of astrophysical questions. Here we
present new photometry for the Galactic globular clusters NGC 5466,
6779, 5053, 6144, Palomar 2, E3, Lynga 7, Palomar 1, and NGC 6366. Our
CMDs extend reliably from the horizontal branch to as much as seven
magnitudes fainter than the main sequence turnoff and represent the
deepest CMDs published to-date for these clusters. Using fiducial
sequences for three standard clusters (M92, NGC 6752, and 47 Tuc) with
well-known metallicities and distances, we perform main sequence fitting
on the target clusters in order to obtain estimates of their distances
and reddenings. These comparisons along with fitting the cluster main
sequences to theoretical isochrones yield ages for the target clusters.
We find that the majority of the clusters have ages that are consistent
with the standard clusters at their metallicities. The exceptions are E3
which appears to be ≈2 Gyr younger than 47 Tuc, and Pal 1, which
could be as much as 8 Gyr younger than 47 Tuc. Support for this work
(GO-10775) was provided by NASA through a grant from the Space Telescope
Science Institute which is operated by the Association of Universities
for Research in Astronomy, Incorporated, under NASA contract NAS5-26555.