Fundamental parameters, helium abundance and distance of X Persei

被引:60
作者
Lyubimkov, LS [1 ]
Rostopchin, SI [1 ]
Roche, P [1 ]
Tarasov, AE [1 ]
机构
[1] UNIV SUSSEX,CTR ASTRON,DEPT PHYS SCI,BRIGHTON BN1 9QH,E SUSSEX,ENGLAND
关键词
stars; abundances; circumstellar matter; emission-line; Be; fundamental parameters; individual; X Per;
D O I
10.1093/mnras/286.3.549
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present spectral observations of the Be/X-ray binary system X Persei/4U 0352 + 30 taken during the recent (1989-91) low-luminosity discless phase. On the basis of new spectroscopic and photometric data the following self-consistent values of effective temperature T-eff, surface gravity g and interstellar absorption A(v) for the visible component of the system are determined: T-eff = 29 500 +/- 1500 K, log g = 4.0 +/- 0.2 and A(v) = 1.05 +/- 0.02. The corresponding spectral classification of the star is B0 V. The helium overabundance He/H = 0.19 is found, as well as the enhanced nitrogen abundance log epsilon(N) approximate to 8.4. Two possible explanations of the He excess are proposed: (a) internal enrichment of the outer layers of a massive star by CNO-cycle products because of a mixing on the main-sequence evolutionary phase or (b) external accretion during the evolution of a massive close binary. The star has a rotational velocity v sin i = 215 +/- 10 km s(-1) and is located at a distance d = 700 +/- 300 pc. The X-ray flux corresponding to this revised distance is of the order of 1-2 x 10(34) erg s(-1) the normal state, and around 10(35) erg s(-1) in the only bright state observed (1974-75). Non-LTE analysis of more recently obtained high-resolution profiles of the He II lambda 4686 line shows that there is no evidence for additional heating during the high-luminosity phase.
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页码:549 / 557
页数:9
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