Hot stellar population synthesis from the UV spectrum: The globular cluster M79 (NGC 1904)

Jorick S. Vink; Sara R. Heap; Allen V. Sweigart; Thierry Lanz; Ivan Hubeny

Hot stellar population synthesis from the UV spectrum: The globular cluster M79 (NGC 1904)

Jorick S. Vink, Sara R. Heap, Allen V. Sweigart, Thierry Lanz, Ivan Hubeny

Research output: Contribution to journal › Article › peer-review

Abstract

We have analyzed the far UV-spectrum of the globular cluster M79. We show that the nearly Gaussian mass distribution of zero-age horizontal-branch stars, as derived by Dixon et al. (1996), is able to reproduce the far-UV Hopkins Utraviolet Telescope (HUT) spectrum, if there is a luminous UV-bright star of about T_eff = 9,500 K within the HUT entrance slit, or, more likely, if the horizontal branch morphology becomes considerably redder in the core of M79, as observed in some other centrally condensed globular clusters. Agreement between the synthetic and observed far-UV spectra for M79 would also be improved if the surface abundances of the heavy elements in the hot horizontal-branch stars were enhanced by radiative diffusion. Contrary to Dixon et al. (1996) we do not need extremely low gravities to reproduce the width of Ly α.

Original language	English (US)
Pages (from-to)	109-116
Number of pages	8
Journal	Astronomy and astrophysics
Volume	345
Issue number	1
State	Published - 1999
Externally published	Yes

Keywords

Galaxy: Globular clusters: Individual: M79
Stars: Evolution
Stars: Hertzsprung-russel (HR) and C-M diagrams
Stars: Horizontal-branch
Ultraviolet: General
Ultraviolet: Stars

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Cite this

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title = "Hot stellar population synthesis from the UV spectrum: The globular cluster M79 (NGC 1904)",

abstract = "We have analyzed the far UV-spectrum of the globular cluster M79. We show that the nearly Gaussian mass distribution of zero-age horizontal-branch stars, as derived by Dixon et al. (1996), is able to reproduce the far-UV Hopkins Utraviolet Telescope (HUT) spectrum, if there is a luminous UV-bright star of about Teff = 9,500 K within the HUT entrance slit, or, more likely, if the horizontal branch morphology becomes considerably redder in the core of M79, as observed in some other centrally condensed globular clusters. Agreement between the synthetic and observed far-UV spectra for M79 would also be improved if the surface abundances of the heavy elements in the hot horizontal-branch stars were enhanced by radiative diffusion. Contrary to Dixon et al. (1996) we do not need extremely low gravities to reproduce the width of Ly α.",

keywords = "Galaxy: Globular clusters: Individual: M79, Stars: Evolution, Stars: Hertzsprung-russel (HR) and C-M diagrams, Stars: Horizontal-branch, Ultraviolet: General, Ultraviolet: Stars",

author = "Vink, {Jorick S.} and Heap, {Sara R.} and Sweigart, {Allen V.} and Thierry Lanz and Ivan Hubeny",

year = "1999",

language = "English (US)",

volume = "345",

pages = "109--116",

journal = "Astronomy and astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

number = "1",

}

TY - JOUR

T1 - Hot stellar population synthesis from the UV spectrum

T2 - The globular cluster M79 (NGC 1904)

AU - Vink, Jorick S.

AU - Heap, Sara R.

AU - Sweigart, Allen V.

AU - Lanz, Thierry

AU - Hubeny, Ivan

PY - 1999

Y1 - 1999

N2 - We have analyzed the far UV-spectrum of the globular cluster M79. We show that the nearly Gaussian mass distribution of zero-age horizontal-branch stars, as derived by Dixon et al. (1996), is able to reproduce the far-UV Hopkins Utraviolet Telescope (HUT) spectrum, if there is a luminous UV-bright star of about Teff = 9,500 K within the HUT entrance slit, or, more likely, if the horizontal branch morphology becomes considerably redder in the core of M79, as observed in some other centrally condensed globular clusters. Agreement between the synthetic and observed far-UV spectra for M79 would also be improved if the surface abundances of the heavy elements in the hot horizontal-branch stars were enhanced by radiative diffusion. Contrary to Dixon et al. (1996) we do not need extremely low gravities to reproduce the width of Ly α.

AB - We have analyzed the far UV-spectrum of the globular cluster M79. We show that the nearly Gaussian mass distribution of zero-age horizontal-branch stars, as derived by Dixon et al. (1996), is able to reproduce the far-UV Hopkins Utraviolet Telescope (HUT) spectrum, if there is a luminous UV-bright star of about Teff = 9,500 K within the HUT entrance slit, or, more likely, if the horizontal branch morphology becomes considerably redder in the core of M79, as observed in some other centrally condensed globular clusters. Agreement between the synthetic and observed far-UV spectra for M79 would also be improved if the surface abundances of the heavy elements in the hot horizontal-branch stars were enhanced by radiative diffusion. Contrary to Dixon et al. (1996) we do not need extremely low gravities to reproduce the width of Ly α.

KW - Galaxy: Globular clusters: Individual: M79

KW - Stars: Evolution

KW - Stars: Hertzsprung-russel (HR) and C-M diagrams

KW - Stars: Horizontal-branch

KW - Ultraviolet: General

KW - Ultraviolet: Stars

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UR - http://www.scopus.com/inward/citedby.url?scp=0007389656&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0007389656

SN - 0004-6361

VL - 345

SP - 109

EP - 116

JO - Astronomy and astrophysics

JF - Astronomy and astrophysics

IS - 1

ER -

Hot stellar population synthesis from the UV spectrum: The globular cluster M79 (NGC 1904)

Abstract

Keywords

ASJC Scopus subject areas

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