Theoretical modeling of GHRS observations of the of/WN-type star R136a5

Alex De Koter; Ivan Hubeny; Sara R. Heap; Thierry Lanz

doi:10.1086/187597

Theoretical modeling of GHRS observations of the of/WN-type star R136a5

Alex De Koter
, Ivan Hubeny
, Sara R. Heap
, Thierry Lanz

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

11 Scopus citations

Abstract

We present a theoretical analysis of the HST GHRS spectrum of R136a5, an O3f/WN star in the R136a cluster in 30 Doradus. Using non-LTE extended and expanding model atmospheres, we find a surprisingly high mass-loss rate Ṁ = 1.8 ± 0.5 × 10^-5 M_⊙ yr^-1 and an effective temperature T_eff = 42.5 ± 2.5 kK. With the observed visual magnitude, this implies a radius R_* = 17 ± 2 R_⊙ and a luminosity L = 8.5 ± 1 × 10⁵ L_⊙. We discuss possible sources of the uncertainties in the derived stellar parameters and conclude that the effective temperature may be underestimated; however, if so, the value of the mass-loss rate would not be affected.

Original language	English (US)
Pages (from-to)	L71-L74
Journal	Astrophysical Journal
Volume	435
Issue number	1 PART 2
DOIs	https://doi.org/10.1086/187597
State	Published - Nov 1 1994
Externally published	Yes

Keywords

Stars: atmospheres
Stars: early-type
Stars: individual (R136a5, Melnick 42)
Stars: mass-loss
Ultraviolet: stars

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1086/187597

Cite this

@article{f771f79e8b344cb480df82149718be3a,

title = "Theoretical modeling of GHRS observations of the of/WN-type star R136a5",

abstract = "We present a theoretical analysis of the HST GHRS spectrum of R136a5, an O3f/WN star in the R136a cluster in 30 Doradus. Using non-LTE extended and expanding model atmospheres, we find a surprisingly high mass-loss rate Ṁ = 1.8 ± 0.5 × 10-5 M⊙ yr-1 and an effective temperature Teff = 42.5 ± 2.5 kK. With the observed visual magnitude, this implies a radius R* = 17 ± 2 R⊙ and a luminosity L = 8.5 ± 1 × 105 L⊙. We discuss possible sources of the uncertainties in the derived stellar parameters and conclude that the effective temperature may be underestimated; however, if so, the value of the mass-loss rate would not be affected.",

keywords = "Stars: atmospheres, Stars: early-type, Stars: individual (R136a5, Melnick 42), Stars: mass-loss, Ultraviolet: stars",

author = "\{De Koter\}, Alex and Ivan Hubeny and Heap, \{Sara R.\} and Thierry Lanz",

year = "1994",

month = nov,

day = "1",

doi = "10.1086/187597",

language = "English (US)",

volume = "435",

pages = "L71--L74",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "1 PART 2",

}

TY - JOUR

T1 - Theoretical modeling of GHRS observations of the of/WN-type star R136a5

AU - De Koter, Alex

AU - Hubeny, Ivan

AU - Heap, Sara R.

AU - Lanz, Thierry

PY - 1994/11/1

Y1 - 1994/11/1

N2 - We present a theoretical analysis of the HST GHRS spectrum of R136a5, an O3f/WN star in the R136a cluster in 30 Doradus. Using non-LTE extended and expanding model atmospheres, we find a surprisingly high mass-loss rate Ṁ = 1.8 ± 0.5 × 10-5 M⊙ yr-1 and an effective temperature Teff = 42.5 ± 2.5 kK. With the observed visual magnitude, this implies a radius R* = 17 ± 2 R⊙ and a luminosity L = 8.5 ± 1 × 105 L⊙. We discuss possible sources of the uncertainties in the derived stellar parameters and conclude that the effective temperature may be underestimated; however, if so, the value of the mass-loss rate would not be affected.

AB - We present a theoretical analysis of the HST GHRS spectrum of R136a5, an O3f/WN star in the R136a cluster in 30 Doradus. Using non-LTE extended and expanding model atmospheres, we find a surprisingly high mass-loss rate Ṁ = 1.8 ± 0.5 × 10-5 M⊙ yr-1 and an effective temperature Teff = 42.5 ± 2.5 kK. With the observed visual magnitude, this implies a radius R* = 17 ± 2 R⊙ and a luminosity L = 8.5 ± 1 × 105 L⊙. We discuss possible sources of the uncertainties in the derived stellar parameters and conclude that the effective temperature may be underestimated; however, if so, the value of the mass-loss rate would not be affected.

KW - Stars: atmospheres

KW - Stars: early-type

KW - Stars: individual (R136a5, Melnick 42)

KW - Stars: mass-loss

KW - Ultraviolet: stars

UR - https://www.scopus.com/pages/publications/12044259152

UR - https://www.scopus.com/pages/publications/12044259152#tab=citedBy

U2 - 10.1086/187597

DO - 10.1086/187597

M3 - Article

AN - SCOPUS:12044259152

SN - 0004-637X

VL - 435

SP - L71-L74

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1 PART 2

ER -

Theoretical modeling of GHRS observations of the of/WN-type star R136a5

Abstract

Keywords

ASJC Scopus subject areas

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