The globular cluster relative ages and the milky way formation time scale

Antonio Aparicio; Antonio Marín-Franch; Giampaolo Piotto; Alfred Rosenberg; Brian Chaboyer; Ata Sarajedini; Michael Siegel; Jay Anderson; Luigi R. Bedin; Aaron Dotter; Maren Hempel; Ivan King; Steven Majewski; Antonino P. Milone; Nathaniel Paust; I. Neill Reid

doi:10.1063/1.3141548

The globular cluster relative ages and the milky way formation time scale

Antonio Aparicio, Antonio Marín-Franch, Giampaolo Piotto, Alfred Rosenberg, Brian Chaboyer, Ata Sarajedini, Michael Siegel, Jay Anderson, Luigi R. Bedin, Aaron Dotter, Maren Hempel, Ivan King, Steven Majewski, Antonino P. Milone, Nathaniel Paust, I. Neill Reid

Astronomy & Astrophysics

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Abstract

The ACS Survey of Galactic Globular Clusters is a Hubble Space Telescope (HST) Treasury program designed to provide a new large, deep and homogeneous photometric database. Based on observations from this program, we have measured precise relative ages for a sample of 64 Galactic globular clusters by comparing the relative position of the clusters' main sequence turn offs, using main-sequence fitting to cross-compare clusters within the sample. This method provides relative ages to a formal precision of 2-7%. We demonstrate that the calcidated relative ages are independent of the choice of theoretical model. We find that the Galactic globidar cluster sample can be divided into two groups - a popidation of old clusters with an intrinsic age dispersion of -̃ 3% and no age-metallicity relation, and a group of younger clusters with an age-metaUicity relation similar to that of the globular clusters associated with the Sagittarius dwarf galaxy. These results are consistent with the Milky Way halo having formed in two phases. The first phase would be compatible with a rapid (<0.8 Gyr) assembling process of the halo, in which the clusters in the old group were formed. The second phase lasted much longer in time and resulted in a group of globidar clusters with a clear age-metallicity relation. It is very tempting to argue that the origin of this second group of clusters is related to the accretion of Milky Way satelUte galaxies, but the origin of the age-metallicity relation remains unclear.

Original language	English (US)
Title of host publication	Probing Stellar Populations Out To The Distant Universe - Cefalu 2008 - Proceedings of the International Conference
Pages	222-229
Number of pages	8
DOIs	https://doi.org/10.1063/1.3141548
State	Published - 2009
Event	International Conference on Probing Stellar Populations Out To The Distant Universe, Cefalu 2008 - Cefalu, Sicily, Italy Duration: Sep 7 2008 → Sep 19 2008

Publication series

Name	AIP Conference Proceedings
Volume	1111
ISSN (Print)	0094-243X
ISSN (Electronic)	1551-7616

Other

Other	International Conference on Probing Stellar Populations Out To The Distant Universe, Cefalu 2008
Country/Territory	Italy
City	Cefalu, Sicily
Period	9/7/08 → 9/19/08

All Science Journal Classification (ASJC) codes

General Physics and Astronomy

Access to Document

10.1063/1.3141548

Cite this

Aparicio, A., Marín-Franch, A., Piotto, G., Rosenberg, A., Chaboyer, B., Sarajedini, A., Siegel, M., Anderson, J., Bedin, L. R., Dotter, A., Hempel, M., King, I., Majewski, S., Milone, A. P., Paust, N., & Reid, I. N. (2009). The globular cluster relative ages and the milky way formation time scale. In Probing Stellar Populations Out To The Distant Universe - Cefalu 2008 - Proceedings of the International Conference (pp. 222-229). (AIP Conference Proceedings; Vol. 1111). https://doi.org/10.1063/1.3141548

@inproceedings{4489de314e16452a9a656d8b72b67395,

title = "The globular cluster relative ages and the milky way formation time scale",

abstract = "The ACS Survey of Galactic Globular Clusters is a Hubble Space Telescope (HST) Treasury program designed to provide a new large, deep and homogeneous photometric database. Based on observations from this program, we have measured precise relative ages for a sample of 64 Galactic globular clusters by comparing the relative position of the clusters' main sequence turn offs, using main-sequence fitting to cross-compare clusters within the sample. This method provides relative ages to a formal precision of 2-7%. We demonstrate that the calcidated relative ages are independent of the choice of theoretical model. We find that the Galactic globidar cluster sample can be divided into two groups - a popidation of old clusters with an intrinsic age dispersion of {\~-} 3% and no age-metallicity relation, and a group of younger clusters with an age-metaUicity relation similar to that of the globular clusters associated with the Sagittarius dwarf galaxy. These results are consistent with the Milky Way halo having formed in two phases. The first phase would be compatible with a rapid (<0.8 Gyr) assembling process of the halo, in which the clusters in the old group were formed. The second phase lasted much longer in time and resulted in a group of globidar clusters with a clear age-metallicity relation. It is very tempting to argue that the origin of this second group of clusters is related to the accretion of Milky Way satelUte galaxies, but the origin of the age-metallicity relation remains unclear.",

author = "Antonio Aparicio and Antonio Mar{\'i}n-Franch and Giampaolo Piotto and Alfred Rosenberg and Brian Chaboyer and Ata Sarajedini and Michael Siegel and Jay Anderson and Bedin, {Luigi R.} and Aaron Dotter and Maren Hempel and Ivan King and Steven Majewski and Milone, {Antonino P.} and Nathaniel Paust and Reid, {I. Neill}",

year = "2009",

doi = "10.1063/1.3141548",

language = "English (US)",

isbn = "9780735406483",

series = "AIP Conference Proceedings",

pages = "222--229",

booktitle = "Probing Stellar Populations Out To The Distant Universe - Cefalu 2008 - Proceedings of the International Conference",

note = "International Conference on Probing Stellar Populations Out To The Distant Universe, Cefalu 2008 ; Conference date: 07-09-2008 Through 19-09-2008",

}

Aparicio, A, Marín-Franch, A, Piotto, G, Rosenberg, A, Chaboyer, B, Sarajedini, A, Siegel, M, Anderson, J, Bedin, LR, Dotter, A, Hempel, M, King, I, Majewski, S, Milone, AP, Paust, N & Reid, IN 2009, The globular cluster relative ages and the milky way formation time scale. in Probing Stellar Populations Out To The Distant Universe - Cefalu 2008 - Proceedings of the International Conference. AIP Conference Proceedings, vol. 1111, pp. 222-229, International Conference on Probing Stellar Populations Out To The Distant Universe, Cefalu 2008, Cefalu, Sicily, Italy, 9/7/08. https://doi.org/10.1063/1.3141548

The globular cluster relative ages and the milky way formation time scale. / Aparicio, Antonio; Marín-Franch, Antonio; Piotto, Giampaolo et al.
Probing Stellar Populations Out To The Distant Universe - Cefalu 2008 - Proceedings of the International Conference. 2009. p. 222-229 (AIP Conference Proceedings; Vol. 1111).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

TY - GEN

T1 - The globular cluster relative ages and the milky way formation time scale

AU - Aparicio, Antonio

AU - Marín-Franch, Antonio

AU - Piotto, Giampaolo

AU - Rosenberg, Alfred

AU - Chaboyer, Brian

AU - Sarajedini, Ata

AU - Siegel, Michael

AU - Anderson, Jay

AU - Bedin, Luigi R.

AU - Dotter, Aaron

AU - Hempel, Maren

AU - King, Ivan

AU - Majewski, Steven

AU - Milone, Antonino P.

AU - Paust, Nathaniel

AU - Reid, I. Neill

PY - 2009

Y1 - 2009

N2 - The ACS Survey of Galactic Globular Clusters is a Hubble Space Telescope (HST) Treasury program designed to provide a new large, deep and homogeneous photometric database. Based on observations from this program, we have measured precise relative ages for a sample of 64 Galactic globular clusters by comparing the relative position of the clusters' main sequence turn offs, using main-sequence fitting to cross-compare clusters within the sample. This method provides relative ages to a formal precision of 2-7%. We demonstrate that the calcidated relative ages are independent of the choice of theoretical model. We find that the Galactic globidar cluster sample can be divided into two groups - a popidation of old clusters with an intrinsic age dispersion of -̃ 3% and no age-metallicity relation, and a group of younger clusters with an age-metaUicity relation similar to that of the globular clusters associated with the Sagittarius dwarf galaxy. These results are consistent with the Milky Way halo having formed in two phases. The first phase would be compatible with a rapid (<0.8 Gyr) assembling process of the halo, in which the clusters in the old group were formed. The second phase lasted much longer in time and resulted in a group of globidar clusters with a clear age-metallicity relation. It is very tempting to argue that the origin of this second group of clusters is related to the accretion of Milky Way satelUte galaxies, but the origin of the age-metallicity relation remains unclear.

AB - The ACS Survey of Galactic Globular Clusters is a Hubble Space Telescope (HST) Treasury program designed to provide a new large, deep and homogeneous photometric database. Based on observations from this program, we have measured precise relative ages for a sample of 64 Galactic globular clusters by comparing the relative position of the clusters' main sequence turn offs, using main-sequence fitting to cross-compare clusters within the sample. This method provides relative ages to a formal precision of 2-7%. We demonstrate that the calcidated relative ages are independent of the choice of theoretical model. We find that the Galactic globidar cluster sample can be divided into two groups - a popidation of old clusters with an intrinsic age dispersion of -̃ 3% and no age-metallicity relation, and a group of younger clusters with an age-metaUicity relation similar to that of the globular clusters associated with the Sagittarius dwarf galaxy. These results are consistent with the Milky Way halo having formed in two phases. The first phase would be compatible with a rapid (<0.8 Gyr) assembling process of the halo, in which the clusters in the old group were formed. The second phase lasted much longer in time and resulted in a group of globidar clusters with a clear age-metallicity relation. It is very tempting to argue that the origin of this second group of clusters is related to the accretion of Milky Way satelUte galaxies, but the origin of the age-metallicity relation remains unclear.

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UR - http://www.scopus.com/inward/citedby.url?scp=67650550494&partnerID=8YFLogxK

U2 - 10.1063/1.3141548

DO - 10.1063/1.3141548

M3 - Conference contribution

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SN - 9780735406483

T3 - AIP Conference Proceedings

SP - 222

EP - 229

BT - Probing Stellar Populations Out To The Distant Universe - Cefalu 2008 - Proceedings of the International Conference

T2 - International Conference on Probing Stellar Populations Out To The Distant Universe, Cefalu 2008

Y2 - 7 September 2008 through 19 September 2008

ER -

The globular cluster relative ages and the milky way formation time scale

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