Rotational broadening and Doppler tomography of the quiescent X-ray nova Centaurus X-4

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Torres, Manuel Angel Perez
Casares, J.
Martínez-Pais, I. G.
Charles, P. A.
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Oxford University Press
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We present high- and intermediate-resolution spectroscopy of the X-ray nova Centaurus X-4 during its quiescent phase. Our analysis of the absorption features supports a K3-K5 V spectral classification for the companion star, which contributes similar or equal to75 per cent of the total flux at Halpha . Using the high-resolution spectra we have measured the rotational broadening of the secondary star to be v sin i =43+/-6 km s(-1) and determined a binary mass ratio of q =0.17+/-0.06. Combining our results for K (2) and q with the published limits for the binary inclination, we constrain the mass of the compact object and the secondary star to the ranges 0.49<M (1) <2.49 M(.) and 0.04<M (2) <0.58 M(.). A Doppler image of the Halpha line shows emission coming from the secondary star, but no hotspot is present. We discuss the possible origins of this emission.
Accretion , Accretion discs , Binaries , Close , Stars , Individual , Centaurus X-4 , Novae , Cataclysmic variables , X-rays , Stars
Torres, M. A. P., Casares, J., Martínez-Pais, I. G. and Charles, P. A. (2002) 'Rotational broadening and Doppler tomography of the quiescent X-ray nova Centaurus X-4', Monthly Notices of the Royal Astronomical Society, 334(1), pp. 233-240. doi: 10.1046/j.1365-8711.2002.05521.x
© 2002, Royal Astronomical Society