The ACS Survey of Galactic Globular Clusters. I. Overview and Clusters without Previous Hubble Space Telescope Photometry

By A. Sarajedini, L. Bedin, B. Chaboyer, Aaron Dotter, M. Siegel, Jay Anderson, A. Aparicio, Ivan R. King, S. Majewski, A. Marín-Franch and 3 more. 2006

407 citations recorded by the source corpus.

We present the first results of a large Advanced Camera for Surveys (ACS) survey of Galactic globular clusters. This Hubble Space Telescope (HST) Treasury project is designed to obtain photometry with S/N (signal-to-noise ratio) ≳10 for main-sequence stars with masses ≳0.2 M⊙ in a sample of globulars using the ACS Wide Field Channel. Here we focus on clusters without previous HST imaging data. These include NGC 5466, NGC 6779, NGC 5053, NGC 6144, Palomar 2, E3, Lyngå 7, Palomar 1, and NGC 6366. Our color-magnitude diagrams (CMDs) extend reliably from the horizontal branch to as much as 7 mag 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 ∼2 Gyr younger than 47 Tuc, and Pal 1, which could be as much as 8 Gyr younger than 47 Tuc.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/feeffa0e201aebc40a5edb700c60983477a15e45

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. Jay Anderson
2. R. Gratton
3. E. Carretta
4. G. Piotto
5. H. Baumgardt
6. A. Bragaglia
7. A. Milone
8. L. Bedin

Citations in the corpus

• The ACS survey of Galactic globular clusters. XII. Photometric binaries along the main sequence (2011, methodology): “The main dataset con- sists in the ACS/WFC images of the Globular Clusters Treasury project (GO10775, PI Sarajedini) that allowed us to obtain uniform and deep photometry for an unprecedented number of GCs (see Sarajedini et al. 2007 and Anderson et al. 2008 for details).”
• A WFC3/HST VIEW OF THE THREE STELLAR POPULATIONS IN THE GLOBULAR CLUSTER NGC 6752 (2013, methodology): “We also used the photometric catalogs presented by Anderson et al. (2008) and obtained from ACS/WFC images taken under GO-10775 (PI: Sarajedini, see Sarajedini et al. 2007).”
• Spectroscopic and photometric evidence of two stellar populations in the Galactic globular cluster NGC 6121 (M 4) (2008, methodology): “The CMD has been corrected for differential reddening (following the same procedure used in Sarajedini et al. 2007) and proper motions.”
• A detached stellar-mass black hole candidate in the globular cluster NGC 3201 (2018, methodology): “For photometric measurements of dense globular clusters, instruments like the Hubble Space Telescope (HST) provide sufficient spatial resolution to obtain independent measurements of most of the stars (Sarajedini et al. 2007).”
• A population of gamma-ray emitting globular clusters seen with the Fermi Large Area Telescope (2010, background): “…(5) Ortolani et al. (2007); (6) Ortolani et al. (1994); (7) Rees & Cudworth (1991); (8) Chaboyer et al. (2000); (9) Lee & Carney (2006); (10) Sarajedini et al. (2007); (11) van den Bosch et al. (2006). clusters in which MSPs have so far been detected4, 6 have distances that are comparable…”
• A stellar census in globular clusters with MUSE: multiple populations chemistry in NGC 2808 (2019, methodology): “For NGC 2808, we used the HST data from the Advanced Camera for Surveys (ACS) of Galactic globular clusters (Sarajedini et al. 2007; Anderson et al. 2008).”
• ASSESSING THE MILKY WAY SATELLITES ASSOCIATED WITH THE SAGITTARIUS DWARF SPHEROIDAL GALAXY (2010, background): “It is possible since Pal 2 is so heavily obscured that its distance (Harris et al. 1997) may have been underestimated, although we note that Sarajedini et al. (2007) derive a similar distance d = 27± 2 kpc based on mainsequence fitting.”
• THE ACS SURVEY OF GALACTIC GLOBULAR CLUSTERS. IX. HORIZONTAL BRANCH MORPHOLOGY AND THE SECOND PARAMETER PHENOMENON (2009, background): “Following Lee (1991), Dotter (2008) showed that a simple relationship between global metallicity and average RGB mass loss, along with stochastic variations, can reproduce the general trend observed in old, roughly coeval Galactic GCs in the HB morphology–metallicity diagram.”
• The Hubble Space TelescopeUV Legacy Survey of Galactic Globular Clusters – V. Constraints on formation scenarios (2015, background): “In this series of papers we report the results of theHubble Space Telescope UV Legacy Survey of Galactic GCsdedicated to the observation of 48 GCs through the filters F275W, F336W, F438W of the Wide Field Camera 3 (WFC3) on boardHST c© 0000 RAS (Piotto et al. 2015, hereafter Paper I ), which complem”
• GLOBULAR CLUSTERS IN THE OUTER GALACTIC HALO: NEW HUBBLE SPACE TELESCOPE/ADVANCED CAMERA FOR SURVEYS IMAGING OF SIX GLOBULAR CLUSTERS AND THE GALACTIC GLOBULAR CLUSTER AGE–METALLICITY RELATION (2011, methodology): “…most recent studies to determine ages from a large sample of GCs, by Maŕın-Franch et al. (2009) and Dotter et al. (2010), rely upon the uniform photometric data set provided by the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) Galactic GC Treasury project (Sarajedini et al. 2007).”
• N-body modelling of globular clusters: masses, mass-to-light ratios and intermediate-mass black holes (2016, methodology): “We therefore calculated a surface brightness profile based on the number counts of bright stars published by the ACS Survey of Galactic Globular Clusters (Sarajedini et al. 2007).”
• The two metallicity groups of the globular cluster M 22: a chemical perspective (2011, methodology): “This technique is similar to the ones adopted by Sarajedini et al. (2007) and Milone et al. (2009).”
• A double stellar generation in the globular cluster NGC 6656 (M 22): Two stellar groups with different iron and s-process element abundances (2009, background): “Since the photometry is affected by spatially variable interstellar reddening, we corrected the CMD for this effect (by using the method described in Sarajedini et al. 2007).”
• The bifurcated age–metallicity relation of Milky Way globular clusters and its implications for the accretion history of the galaxy (2013, methodology): “We rely on the ages that V13 recently derived for the 55 Galactic GCs that they considered (based on photometry from Sarajedini et al. 2007), along with their adopted [Fe/H] values (from the compilation given by Carretta et al. 2009a).”
• The ACS Survey of Galactic Globular Clusters. II. Stellar Evolution Tracks, Isochrones, Luminosity Functions, and Synthetic Horizontal-Branch Models (2007, background): “ar X iv :0 The ACS Survey of Galactic Globular Clusters, an HST Treasury Project, will deliver high quality, homogeneous photometry of 65 globular clusters.”
• Vvv dr1: the first data release of the milky way bulge and southern plane from the near-infrared eso public survey vista variables in the via lactea (2011, methodology): “This is based on the fact that the stellar densities in both our fields are assumed to be significantly lower than that within the central region of a globular cluster, targeted bythe ACS Globular Cluster Survey.”
• Mean proper motions, space orbits, and velocity dispersion profiles of Galactic globular clusters derived fromGaiaDR2 data (2018, methodology): “The stellar mass functions of 42 clusters were already used by us in Baumgardt & Hilker (2018), based mainly on the results obtained by Sollima & Baumgardt (2017) from an analysis of the HST/ACS Treasury project data (Sarajedini et al. 2007).”
• A catalogue of masses, structural parameters, and velocity dispersion profiles of 112 Milky Way globular clusters (2018, methodology): “Sollima & Baumgardt (2017) found a correlation between the mass function slope of 35 globular clusters from the Globular Cluster ACS Treasury Project and their halfmass relaxation times in the sense that clusters with more positive mass function slopes (fewer low-mass stars) have smaller relaxation ”
• The second and third parameters of the horizontal branch in globular clusters (2010, background): “The HSTACS survey (Sarajedini et al. 2007) is providing new, very high quality data, which will largely supersede those older catalogues; unfortunately, this data set is not publicly available yet.”