| Autor: |
Zurita, C., Casares, J., Shahbaz, T., Wagner, R. M., Foltz, C. B., Rodríguez-Gil, P., Hynes, R. I., Charles, P. A., Ryan, E., Schwarz, G., Starrfield, S. G. |
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| Zdroj: |
Monthly Notices of the Royal Astronomical Society; 7/11/2002, Vol. 333 Issue 4, p791-799, 9p |
| Abstrakt: |
We present the results of our monitoring of the halo black hole soft X-ray transient (SXT) XTE J1118+480 during its decline to quiescence. The system has decayed 0.5 mag from 2000 December to its present near-quiescent level at R≃18.65 (2001 June). The ellipsoidal light curve is distorted by an additional modulation that we interpret as a superhump of P[sub sh]=0.17049(1) d i.e. 0.3 per cent longer than the orbital period. This implies a disc precession period P[sub prec]∼52 d . After correcting the average phase-folded light curve for veiling, the amplitude difference between the minima suggests that the binary inclination angle lies in the range i=71–82° . However, we urge caution in the interpretation of these values because of residual systematic contamination of the ellipsoidal light curve by the complex form of the superhump modulation. The orbital-mean Hα profiles exhibit clear velocity variations with ∼500 km s[sup -1] amplitude. We interpret this as the first spectroscopic evidence of an eccentric precessing disc. [ABSTRACT FROM AUTHOR] |
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