A FEROS spectroscopic study of the extreme O supergiant He 3-759 - Astrophysics > Solar and Stellar AstrophysicsReportar como inadecuado




A FEROS spectroscopic study of the extreme O supergiant He 3-759 - Astrophysics > Solar and Stellar Astrophysics - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: We present a study of the extreme O-type supergiant He 3-759 using newhigh-resolution FEROS data, revealing that it is a near spectroscopic twin ofHD 151804 O8 Iaf. We investigate the extinction towards He 3-759 using avariety of methods, revealing A V ~ 4.7 mag. If we assume He 3-759 has anidentical absolute K-band magnitude to HD 151804 we find that it lies in theSagittarius-Carina spiral arm at a distance of ~6.5 kpc. We derive the physicaland wind properties for He 3-759, revealing T* = 30.5 kK, log L-Lsun = 5.9and dM-dt = 10^-5.17 Msun-yr for a clumped wind whose terminal velocity isestimated at 1000 km-s. The atmosphere of He 3-759 is enriched in helium X He= 49% and nitrogen X N = 0.3%. A reanalysis of HD 151804 and HD 152408WN9ha reveals similar parameters except that the WN9ha star possesses astronger wind and reduced surface hydrogen content. HD 151804 and HD 152408 liewithin the Sco OB1 association, with initial masses of ~60 Msun and ages ~2.7Myr, consistent with NGC 6231 cluster members using standard Geneva isochrones.Improved agreement with observed surface abundances are obtained for similarinitial masses with more recent Geneva group predictions from which higher agesof ~3.75 Myr are obtained. No young, massive star cluster is known to beassociated with He 3-759.



Autor: P.A. Crowther Sheffield, C.J. Evans UK ATC

Fuente: https://arxiv.org/



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