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S. J. Stokes (U. Wyoming), J. M. Evans (Austin Peay State University & U. Wyoming), A. Bianchini (U. Padova Italy & U. Wyoming), R. Canterna (U. Wyoming)
We have analyzed 17 medium resolution spectra of RW Sex taken in 1988 at La Silla in the spectral range is 4000-5000 {Å} with a dispersion of 60 {Å}/mm and spectral resolution of about 2 {Å}/pixel. The mean spectrum of the object shows the continuum energy distribution slightly brighter and steeper than that observed by Beuermann, Stasiewski and Schwope (1992). In both cases the slope seems to be steeper that the \lambda-2.33 power law predicted for standard accretion discs (see Warner 1995). This might be due to uncertain flux calibration or to the dramatic intrinsic variability of this nova-like system (Honeycutt et al. 1998). Like in Beuerman et al.'s, the hydrogen and the HeI lines appear in absorption with superimposed central emission components. Relatively weak emissions from HeII at \lambda\lambda 4542,4686 and the blend CIII+NIII at \lambda4640-50 are also seen. The peaks of the narrow emissions components of H\beta, HeI\lambda4471 and HeI\lambda4922 have been measured using Gaussian fittings. The new ephemeris are:
T0(HJD) = 2446486.5061 ±0.0010 + 0.245064 ±0.000004
The radial velocity curve produced by the absorption components of the hydrogen and the HeI lines are in antiphase with respect to that produced by the emission cores. The amplitudes of all the radial velocity curves are consistent with those shown by Beuermann, Stasiewski and Schwope (1992). According to these authors the absorption lines are produced in the optically thick accretion disc while the narrow emissions arise from the heated atmosphere of the secondary. We fail however to detect the broad emission components observed by these authors and attributed to the hot disc corona. This point should deserve future investigation.
The author(s) of this abstract have provided an email address for comments about the abstract: antonio1@sole.pd.astro.it