\documentstyle[twoside, epsf]{article}

\input ibvs2.sty

\def\ec{EC~10578-2935}

\begin{document}
\IBVShead{5567}{5 October 2004}

\IBVStitle{V393 H\lowercase{ya}: a Nova-Like with Variable Emission}


\IBVSauth{Dall, T.H.; Schmidtobreick, L.}

\IBVSinsto{European Southern Observatory, Casilla 19001, Santiago 19, Chile}

\SIMBADobjAlias{V393 Hya}{EC 10578-2935}
\IBVStyp{ NL }
\IBVSkey{spectroscopy}
\IBVSabs{We present the first high-resolution spectra of the suspected}
\IBVSabs{cataclysmic variable V393 Hya. The spectrum is essentially} 
\IBVSabs{featureless except for clear H$\alpha$ emission, which shows that}
\IBVSabs{V393 Hya is indeed a nova-like object, probably with a low-mass}
\IBVSabs{secondary seen under low inclination.}


\begintext

The Edinburgh-Cape Blue Object Survey (Kilkenny et al.~1997) classified the object \ec\ as a possible 
cataclysmic variable (CV), a classification later confirmed by Sefako et al.~(1999). These classifications were 
based on low resolution spectrograms (100\,\AA/mm dispersion, corresponding to 4\,\AA\ resolution), and the 
colors $B-V = -0.01$ and $U-B = -0.83$, which placed the object just below the black body line in ($U-B,B-V$),
consistent with the weak H$\beta$ and H$\gamma$ emission seen in the spectrograms.   These facts have 
resulted in the GCVS classification NL: (possible nova-like) under the name V393~Hya (Kazarovets et al. 2003).

We have obtained the first high-resolution (R$\sim$48000)
spectrum of \ec, using FEROS at the ESO/MPI-2.20m telescope at La Silla, Chile on 2004-01-13 (HJD 2453018.84285), during technical tests. 
Standard data reduction was performed with MIDAS
including bias and flatfield correction, order extraction and wavelength calibration.
Finally, a crude flux calibration was performed using a standard star taken several hours earlier. 
The spectra have a FWHM resolution of 0.15\AA\ and cover the 
range 3800--9000\AA .  The S/N in the spectrum
is only around 10 over most of the spectral range.

\IBVSfig{7.0cm}{5567-f1.eps}{The region around H$\alpha$, with a two-gaussian fit to the profile.}
\IBVSfigKey{5567-f1.eps}{V393 Hya}{spectrum}


The spectrum is essentially flat and featureless, the only exception being weak H$\alpha$ in emission, as
shown in Fig.~1. 

The fit in Fig.~1 is a two-gaussian fit, with the gaussians centered at 6560.0\,\AA\ and 6567.0\,\AA\ respectively.
The width of both profiles is 3.5\,\AA\ and we measure FWZI $\approx$
16\,\AA , resulting in radial velocities of 160\,km/s and 740\,km/s 
respectively. These low values indicate that the system is seen at low
inclination, with the typical double profile of the accretion disc barely
resolved at our high spectral resolution. 


Chen et al.~(2001) found all Balmer lines in emission, although weak, plus He\,{\sc ii} and N\,{\sc iii}/C\,{\sc iii}. They estimate
FWZI~$\sim$~20\,\AA\ for the Balmer lines.
Our spectrum is completely flat and featureless at all these positions, which partly is due to our low S/N.
We establish the equivalent width for H$\alpha$ as 
$W(\rm H\alpha)$ = $-$18\,\AA .
For the other Balmer lines as well as for He\,{\sc ii} and the N\,{\sc iii}/C\,{\sc iii}
blend we can only give upper limits to the equivalent widths, assuming
the lines have the same shape as H$\alpha$. We derive $W < 14$\,\AA\ for these lines.

The system seem to show variable emission when comparing our findings with the literature. Also 
Chen et al.~(2001) find that the strength of the Balmer lines changed between their 1990 and 1992 data sets.

We find that the continuum fits a power law of the type $\lambda^{-2.7}$, consistent with a hot accretion disk,
as found e.g. for old novae (Schmidtobreick et al., 2004).
Together with the weakness of the emission lines we
conclude that V393\,Hya is a cataclysmic variable of nova-like subtype,
showing a hot accretion disc. The unfortunately rather low
inclination under which V393\,Hya is seen, makes it an unpromising object
for time resolved follow--up studies of the accretion disc.


\vskip 1cm

\references
Chen, A., O'Donoghue, D., Stobie, R. S., Kilkenny, D., Warner, B., 2001, {\it MNRAS}, {\bf 325}, 89 
%%\BIBCODE{2001MNRAS.325...89C}

Kazarovets, E.V, Kireeva, N.N., Samus, N.N., Durlevich, O.V., 2003, {\it IBVS}, 5422
%%\BIBCODE{2003IBVS.5422....1K}

Kilkenny, D., O'Donoghue, D., Koen, C., Stobie, R.S., Chen, A., 1997, {\it MNRAS}, {\bf 287}, 867
%%\BIBCODE{1997MNRAS.287..867K}

Schmidtobreick, L., Tappert, C., Bianchini, A., Mennickent, R.E., 2004, {\it A\&A}, submitted

Sefako, R.R., Glass, I.S., Kilkenny, D., de Jaeger, O.C., Stobie, R.S., O'Donoghue, D., Koen, C., 1999, {\it MNRAS}, {\bf 309}, 1043 
%%\BIBCODE{1999MNRAS.309.1043S}

\endreferences


\end{document}

