Far-ultraviolet imaging of the globular cluster NGC 6681 with WFPC2

Alan M. Watson; Jeremy R. Mould; John S. Gallagher; Gilda E. Ballester; Christopher J. Burrows; Stefano Casertano; John T. Clarke; David Crisp; Richard E. Griffiths; J. Jeff Hester; John G. Hoessel; Jon A. Holtzman; Paul Scowen; Karl R. Stapelfeldt; John T. Trauger; James A. Westphal

doi:10.1086/187593

Far-ultraviolet imaging of the globular cluster NGC 6681 with WFPC2

Alan M. Watson, Jeremy R. Mould, John S. Gallagher, Gilda E. Ballester, Christopher J. Burrows, Stefano Casertano, John T. Clarke, David Crisp, Richard E. Griffiths, J. Jeff Hester, John G. Hoessel, Jon A. Holtzman, Paul Scowen, Karl R. Stapelfeldt, John T. Trauger, James A. Westphal

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17 Scopus citations

Abstract

We have imaged the globular cluster NGC 6681 in the far-UV and visible with WFPC2 on the HST. Our far-UV images show a sparsely populated and fully resolved central region, and we detect 122 stars. The far-UV to visible color-magnitude diagram shows a well-defined horizontal branch with no evidence for hot, more evolved descendants. We find one hot horizontal-branch star significantly below the model zero-age horizontal branch, but the rest are consistent with evolutionary models within uncertainties in calibration, distance, and reddening. The center of the cluster harbors two luminous blue stragglers. Our far-UV images graphically confirm that there is no steep density gradient at small radii among the horizontal-branch stars of this post-core-collapse cluster and show no evidence for significant color gradients.

Original language	English (US)
Pages (from-to)	L55-L58
Journal	Astrophysical Journal
Volume	435
Issue number	1 PART 2
DOIs	https://doi.org/10.1086/187593
State	Published - Nov 1 1994

Keywords

Globular clusters: individual: (NGC 6681)
Stars: evolution
Stars: horizontal-branch
Ultraviolet: stars

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Access to Document

10.1086/187593

Cite this

Watson, A. M., Mould, J. R., Gallagher, J. S., Ballester, G. E., Burrows, C. J., Casertano, S., Clarke, J. T., Crisp, D., Griffiths, R. E., Hester, J. J., Hoessel, J. G., Holtzman, J. A., Scowen, P., Stapelfeldt, K. R., Trauger, J. T., & Westphal, J. A. (1994). Far-ultraviolet imaging of the globular cluster NGC 6681 with WFPC2. Astrophysical Journal, 435(1 PART 2), L55-L58. https://doi.org/10.1086/187593

Watson, AM, Mould, JR, Gallagher, JS, Ballester, GE, Burrows, CJ, Casertano, S, Clarke, JT, Crisp, D, Griffiths, RE, Hester, JJ, Hoessel, JG, Holtzman, JA, Scowen, P, Stapelfeldt, KR, Trauger, JT & Westphal, JA 1994, 'Far-ultraviolet imaging of the globular cluster NGC 6681 with WFPC2', Astrophysical Journal, vol. 435, no. 1 PART 2, pp. L55-L58. https://doi.org/10.1086/187593

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title = "Far-ultraviolet imaging of the globular cluster NGC 6681 with WFPC2",

abstract = "We have imaged the globular cluster NGC 6681 in the far-UV and visible with WFPC2 on the HST. Our far-UV images show a sparsely populated and fully resolved central region, and we detect 122 stars. The far-UV to visible color-magnitude diagram shows a well-defined horizontal branch with no evidence for hot, more evolved descendants. We find one hot horizontal-branch star significantly below the model zero-age horizontal branch, but the rest are consistent with evolutionary models within uncertainties in calibration, distance, and reddening. The center of the cluster harbors two luminous blue stragglers. Our far-UV images graphically confirm that there is no steep density gradient at small radii among the horizontal-branch stars of this post-core-collapse cluster and show no evidence for significant color gradients.",

keywords = "Globular clusters: individual: (NGC 6681), Stars: evolution, Stars: horizontal-branch, Ultraviolet: stars",

author = "Watson, {Alan M.} and Mould, {Jeremy R.} and Gallagher, {John S.} and Ballester, {Gilda E.} and Burrows, {Christopher J.} and Stefano Casertano and Clarke, {John T.} and David Crisp and Griffiths, {Richard E.} and Hester, {J. Jeff} and Hoessel, {John G.} and Holtzman, {Jon A.} and Paul Scowen and Stapelfeldt, {Karl R.} and Trauger, {John T.} and Westphal, {James A.}",

year = "1994",

month = nov,

day = "1",

doi = "10.1086/187593",

language = "English (US)",

volume = "435",

pages = "L55--L58",

journal = "Astrophysical Journal",

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TY - JOUR

T1 - Far-ultraviolet imaging of the globular cluster NGC 6681 with WFPC2

AU - Watson, Alan M.

AU - Mould, Jeremy R.

AU - Gallagher, John S.

AU - Ballester, Gilda E.

AU - Burrows, Christopher J.

AU - Casertano, Stefano

AU - Clarke, John T.

AU - Crisp, David

AU - Griffiths, Richard E.

AU - Hester, J. Jeff

AU - Hoessel, John G.

AU - Holtzman, Jon A.

AU - Scowen, Paul

AU - Stapelfeldt, Karl R.

AU - Trauger, John T.

AU - Westphal, James A.

PY - 1994/11/1

Y1 - 1994/11/1

N2 - We have imaged the globular cluster NGC 6681 in the far-UV and visible with WFPC2 on the HST. Our far-UV images show a sparsely populated and fully resolved central region, and we detect 122 stars. The far-UV to visible color-magnitude diagram shows a well-defined horizontal branch with no evidence for hot, more evolved descendants. We find one hot horizontal-branch star significantly below the model zero-age horizontal branch, but the rest are consistent with evolutionary models within uncertainties in calibration, distance, and reddening. The center of the cluster harbors two luminous blue stragglers. Our far-UV images graphically confirm that there is no steep density gradient at small radii among the horizontal-branch stars of this post-core-collapse cluster and show no evidence for significant color gradients.

AB - We have imaged the globular cluster NGC 6681 in the far-UV and visible with WFPC2 on the HST. Our far-UV images show a sparsely populated and fully resolved central region, and we detect 122 stars. The far-UV to visible color-magnitude diagram shows a well-defined horizontal branch with no evidence for hot, more evolved descendants. We find one hot horizontal-branch star significantly below the model zero-age horizontal branch, but the rest are consistent with evolutionary models within uncertainties in calibration, distance, and reddening. The center of the cluster harbors two luminous blue stragglers. Our far-UV images graphically confirm that there is no steep density gradient at small radii among the horizontal-branch stars of this post-core-collapse cluster and show no evidence for significant color gradients.

KW - Globular clusters: individual: (NGC 6681)

KW - Stars: evolution

KW - Stars: horizontal-branch

KW - Ultraviolet: stars

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JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1 PART 2

ER -

Far-ultraviolet imaging of the globular cluster NGC 6681 with WFPC2

Abstract

Keywords

ASJC Scopus subject areas

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