An HST/WFPC2 survey of bright young clusters in M31 I. VdB0, a massive star cluster seen at t ≃ a 25 Myr

S. Perina; P. Barmby; M. A. Beasley; M. Bellazzini; J. P. Brodie; D. Burstein; J. G. Cohen; L. Federici; F. Fusi Pecci; S. Galleti; P. W. Hodge; J. P. Huchra; M. Kissler-Patig; T. H. Puzia; J. Strader

doi:10.1051/0004-6361:200810725

An HST/WFPC2 survey of bright young clusters in M31 I. VdB0, a massive star cluster seen at t ≃ a 25 Myr

S. Perina, P. Barmby, M. A. Beasley, M. Bellazzini, J. P. Brodie, D. Burstein, J. G. Cohen, L. Federici, F. Fusi Pecci, S. Galleti, P. W. Hodge, J. P. Huchra, M. Kissler-Patig, T. H. Puzia, J. Strader

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Abstract

Aims. We introduce our imaging survey of possible young massive globular clusters in M31 performed with the Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space Telescope (HST). We obtained shallow (to B ∼ 25) photometry of individual stars in 20 candidate clusters. We present here details of the data reduction pipeline that is being applied to all the survey data and describe its application to the brightest among our targets, van den Bergh 0 (VdB0), taken as a test case. Methods. Point spread function fitting photometry of individual stars was obtained for all the WFPC2 images of VdBO and the completeness of the final samples was estimated using an extensive set of artificial stars experiments. The reddening, the age and the metallicity of the cluster were estimated by comparing the observed color magnitude diagram (CMD) with theoretical isochrones. Structural parameters were obtained from model-fitting to the intensity profiles measured within circular apertures on the WFPC2 images. Results. Under the most conservative assumptions, the stellar mass of VdBO is M > 2.4 × 10⁴ M_⊙, but our best estimates lie in the range ≃4-9 × 10⁴ M _⊙. The CMD of VdBO is best reproduced by models having solar metallicity and age ≃ 25 Myr. Ages less than ≃12 Myr and greater than ≃60 Myr are clearly ruled out by the available data. The cluster has a remarkable number of red super giants (≳18) and a CMD very similar to Large Magellanic Cloud clusters usually classified as young globulars such as NGC 1850, for example. Conclusions. VdBO is significantly brighter (≳1 mag) than Galactic open clusters of similar age. Its present-day mass and half-light radius (r_h, = 7.4 pc) are more typical of faint globular clusters than of open clusters. However, given its position within the disk of M31, it is expected to be destroyed by dynamical effects, in particular by encounters with giant molecular clouds, within the next ∼4 Gyr.

Original language	English
Pages (from-to)	933-948
Number of pages	16
Journal	Astronomy and Astrophysics
Volume	494
Issue number	3
DOIs	https://doi.org/10.1051/0004-6361:200810725
State	Published - Feb 2009
Externally published	Yes

Keywords

Galaxies: individual: M31
Galaxies: star clusters
Stars: evolution
Stars: supergiants

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10.1051/0004-6361:200810725

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Perina, S., Barmby, P., Beasley, M. A., Bellazzini, M., Brodie, J. P., Burstein, D., Cohen, J. G., Federici, L., Fusi Pecci, F., Galleti, S., Hodge, P. W., Huchra, J. P., Kissler-Patig, M., Puzia, T. H., & Strader, J. (2009). An HST/WFPC2 survey of bright young clusters in M31 I. VdB0, a massive star cluster seen at t ≃ a 25 Myr. Astronomy and Astrophysics, 494(3), 933-948. https://doi.org/10.1051/0004-6361:200810725

@article{7f435e811ded48f387d051e371193c0c,

title = "An HST/WFPC2 survey of bright young clusters in M31 I. VdB0, a massive star cluster seen at t ≃ a 25 Myr",

abstract = "Aims. We introduce our imaging survey of possible young massive globular clusters in M31 performed with the Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space Telescope (HST). We obtained shallow (to B ∼ 25) photometry of individual stars in 20 candidate clusters. We present here details of the data reduction pipeline that is being applied to all the survey data and describe its application to the brightest among our targets, van den Bergh 0 (VdB0), taken as a test case. Methods. Point spread function fitting photometry of individual stars was obtained for all the WFPC2 images of VdBO and the completeness of the final samples was estimated using an extensive set of artificial stars experiments. The reddening, the age and the metallicity of the cluster were estimated by comparing the observed color magnitude diagram (CMD) with theoretical isochrones. Structural parameters were obtained from model-fitting to the intensity profiles measured within circular apertures on the WFPC2 images. Results. Under the most conservative assumptions, the stellar mass of VdBO is M > 2.4 × 104 M⊙, but our best estimates lie in the range ≃4-9 × 104 M ⊙. The CMD of VdBO is best reproduced by models having solar metallicity and age ≃ 25 Myr. Ages less than ≃12 Myr and greater than ≃60 Myr are clearly ruled out by the available data. The cluster has a remarkable number of red super giants (≳18) and a CMD very similar to Large Magellanic Cloud clusters usually classified as young globulars such as NGC 1850, for example. Conclusions. VdBO is significantly brighter (≳1 mag) than Galactic open clusters of similar age. Its present-day mass and half-light radius (rh, = 7.4 pc) are more typical of faint globular clusters than of open clusters. However, given its position within the disk of M31, it is expected to be destroyed by dynamical effects, in particular by encounters with giant molecular clouds, within the next ∼4 Gyr.",

keywords = "Galaxies: individual: M31, Galaxies: star clusters, Stars: evolution, Stars: supergiants",

author = "S. Perina and P. Barmby and Beasley, {M. A.} and M. Bellazzini and Brodie, {J. P.} and D. Burstein and Cohen, {J. G.} and L. Federici and {Fusi Pecci}, F. and S. Galleti and Hodge, {P. W.} and Huchra, {J. P.} and M. Kissler-Patig and Puzia, {T. H.} and J. Strader",

year = "2009",

month = feb,

doi = "10.1051/0004-6361:200810725",

language = "English",

volume = "494",

pages = "933--948",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

number = "3",

}

Perina, S, Barmby, P, Beasley, MA, Bellazzini, M, Brodie, JP, Burstein, D, Cohen, JG, Federici, L, Fusi Pecci, F, Galleti, S, Hodge, PW, Huchra, JP, Kissler-Patig, M, Puzia, TH & Strader, J 2009, 'An HST/WFPC2 survey of bright young clusters in M31 I. VdB0, a massive star cluster seen at t ≃ a 25 Myr', Astronomy and Astrophysics, vol. 494, no. 3, pp. 933-948. https://doi.org/10.1051/0004-6361:200810725

TY - JOUR

T1 - An HST/WFPC2 survey of bright young clusters in M31 I. VdB0, a massive star cluster seen at t ≃ a 25 Myr

AU - Perina, S.

AU - Barmby, P.

AU - Beasley, M. A.

AU - Bellazzini, M.

AU - Brodie, J. P.

AU - Burstein, D.

AU - Cohen, J. G.

AU - Federici, L.

AU - Fusi Pecci, F.

AU - Galleti, S.

AU - Hodge, P. W.

AU - Huchra, J. P.

AU - Kissler-Patig, M.

AU - Puzia, T. H.

AU - Strader, J.

PY - 2009/2

Y1 - 2009/2

N2 - Aims. We introduce our imaging survey of possible young massive globular clusters in M31 performed with the Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space Telescope (HST). We obtained shallow (to B ∼ 25) photometry of individual stars in 20 candidate clusters. We present here details of the data reduction pipeline that is being applied to all the survey data and describe its application to the brightest among our targets, van den Bergh 0 (VdB0), taken as a test case. Methods. Point spread function fitting photometry of individual stars was obtained for all the WFPC2 images of VdBO and the completeness of the final samples was estimated using an extensive set of artificial stars experiments. The reddening, the age and the metallicity of the cluster were estimated by comparing the observed color magnitude diagram (CMD) with theoretical isochrones. Structural parameters were obtained from model-fitting to the intensity profiles measured within circular apertures on the WFPC2 images. Results. Under the most conservative assumptions, the stellar mass of VdBO is M > 2.4 × 104 M⊙, but our best estimates lie in the range ≃4-9 × 104 M ⊙. The CMD of VdBO is best reproduced by models having solar metallicity and age ≃ 25 Myr. Ages less than ≃12 Myr and greater than ≃60 Myr are clearly ruled out by the available data. The cluster has a remarkable number of red super giants (≳18) and a CMD very similar to Large Magellanic Cloud clusters usually classified as young globulars such as NGC 1850, for example. Conclusions. VdBO is significantly brighter (≳1 mag) than Galactic open clusters of similar age. Its present-day mass and half-light radius (rh, = 7.4 pc) are more typical of faint globular clusters than of open clusters. However, given its position within the disk of M31, it is expected to be destroyed by dynamical effects, in particular by encounters with giant molecular clouds, within the next ∼4 Gyr.

AB - Aims. We introduce our imaging survey of possible young massive globular clusters in M31 performed with the Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space Telescope (HST). We obtained shallow (to B ∼ 25) photometry of individual stars in 20 candidate clusters. We present here details of the data reduction pipeline that is being applied to all the survey data and describe its application to the brightest among our targets, van den Bergh 0 (VdB0), taken as a test case. Methods. Point spread function fitting photometry of individual stars was obtained for all the WFPC2 images of VdBO and the completeness of the final samples was estimated using an extensive set of artificial stars experiments. The reddening, the age and the metallicity of the cluster were estimated by comparing the observed color magnitude diagram (CMD) with theoretical isochrones. Structural parameters were obtained from model-fitting to the intensity profiles measured within circular apertures on the WFPC2 images. Results. Under the most conservative assumptions, the stellar mass of VdBO is M > 2.4 × 104 M⊙, but our best estimates lie in the range ≃4-9 × 104 M ⊙. The CMD of VdBO is best reproduced by models having solar metallicity and age ≃ 25 Myr. Ages less than ≃12 Myr and greater than ≃60 Myr are clearly ruled out by the available data. The cluster has a remarkable number of red super giants (≳18) and a CMD very similar to Large Magellanic Cloud clusters usually classified as young globulars such as NGC 1850, for example. Conclusions. VdBO is significantly brighter (≳1 mag) than Galactic open clusters of similar age. Its present-day mass and half-light radius (rh, = 7.4 pc) are more typical of faint globular clusters than of open clusters. However, given its position within the disk of M31, it is expected to be destroyed by dynamical effects, in particular by encounters with giant molecular clouds, within the next ∼4 Gyr.

KW - Galaxies: individual: M31

KW - Galaxies: star clusters

KW - Stars: evolution

KW - Stars: supergiants

UR - http://www.scopus.com/inward/record.url?scp=60349087636&partnerID=8YFLogxK

U2 - 10.1051/0004-6361:200810725

DO - 10.1051/0004-6361:200810725

M3 - Review article

AN - SCOPUS:60349087636

SN - 0004-6361

VL - 494

SP - 933

EP - 948

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

IS - 3

ER -

An HST/WFPC2 survey of bright young clusters in M31 I. VdB0, a massive star cluster seen at t ≃ a 25 Myr

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Keywords

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