COMMISSIONS 27 AND 42 OF THE IAU
                INFORMATION BULLETIN ON VARIABLE STARS
                             Number 4072

                                                  Konkoly Observatory
                                                  Budapest
                                                  18 August 1994

                                                  HU ISSN 0374 - 0676


             SPECTROSCOPY OF FAINT CATACLYSMIC VARIABLES I


          TV Corvi (Tombaugh CV, 1217-18, Crv1, Nova Corvi 1931)


  This star was originally discovered by C. Tombaugh in 1931 during his search leading
to the discovery of the planet Pluto. It had laid undisturbed for 60 years until it was
rediscovered by Levy et al. (1990). They showed that TV Crv has a large outburst
amplitude and they also present spectra at outburst as well as minimum light photometric
data. The latter showed no periodic modulations.
  Figure 1 shows our unfluxed spectrum obtained for TV Crv. AAVSO data (Mattei
1993) shows no indication of an outburst for -12/+30 days from our observation, so we
assume it was made when TV Crv was near minimum. As the data are not fluxed, we
cannot comment on the nature of the slope of the continuum, however, the spectrum seems
to be typical of a low mass transfer rate system. Emission lines of hydrogen and helium
are seen. The apparent emission features near 5570A and 6300A are due to incomplete
night sky line subtraction.
  The featureless red continuum shows no evidence of a secondary star. The large outburst 
amplitude for TV Crv (~8 mags; Levy et al. 1990) suggests that this star is a
tremendous outburst amplitude dwarf nova (TOAD). All confirmed TOADs known to
date have measured orbital periods which are <=2.5 hrs (Howell et al. 1994). Thus, it was
likely, given the probable low mass transfer rate and the large outburst amplitude, that
TV Crv has a <=2.5 hr orbital period. Recent high-speed photometry of TV Crv during
its June 1994 outburst shows superhumps with a period near 1.6 hrs (Howell et al. 1995).


                                AH Eridani

  This star is likely to be a DQ Her system with a spin period of 42 minutes (Szkody
et al. 1989) and the orbital period is still unknown. There is possible confirmation of
this period in the X-ray range from ROSAT observations (Szkody et al., 1993). Szkody
(1987) published a spectrum of AH Eri covering the wavelengths from 3400 to 5400A. Her
spectrum contained strong emission lines of H and He. Our spectrum, shown in Figure 2,
is similar to Szkody's but has a wavelength coverage from 4000-9000A. It also shows strong
emission lines due to H and He. There are indications of additional weaker emission lines
(Fe II) throughout the spectrum. The flat continuum shape from red to blue is consistent
with AH Eri having little to no accretion disk. Since the Balmer decrement is flat, the
optical extinction is not a likely contribution to the redness of the continuum. Despite
the possible DQ Her status, HeII is not detected.


                                [FIGURE 1]

  Figure 1. Unfluxed spectrum of TV Crv taken with the INT on La Palma.

                                [FIGURE 2]

                    Figure 2. MMT spectrum of AH Eri.


 The red spectrum shows clear evidence for TiO bandheads near 5900A, 6200A, 6600A,
and 7000A degrading to the red. Using K and M star templates observed during our run,
we performed a Chi-square test on the difference between each template and AH Eri over the
wavelength range of 5000A to 9000A. We found a best fit match for the TiO bands to be
an M3-M5 star. This spectral type usually implies a short orbital period (<=3 hrs). The
data are very noisy beyond 8000A.
 Observations reported here were made at the Multiple-Mirror Telescope and at the
INT on La Palma.

                       Table 1. Observing log

Star       UT Date     UT Start   Int. Time     Spectral   V^a)
                                               Resolution
TV Crv   1993 Mar 27    01:55      3072 sec         6A      -
AH Eri   1992 Sep 02    10:35      1800 sec        15A     18.5

a) V magnitude derived from numerical filter convolutions of the spectra.


                        Steve B. HOWELL
                        Planetary Science Institute
                        620 N. 6th Avenue
                        Tucson AZ 85705
                        USA

                        James LIEBERT
                        Steward Observatory
                        University of Arizona
                        Tucson AZ 85721
                        USA

                        Keith O. MASON
                        Mullard Space Science Laboratory
                        University College London
                        Holmbury St. Mary, Dorking
                        Surrey RH5 6NT
                        United Kingdom



References:

Howell, S.B., Szkody, P., and Cannizzo, J.K., 1994, ApJ, submitted [BIBCODE 1995ApJ...439..337H ]
Howell, S.B. et al., 1995, in preparation
Levy, D.H., Howell, S.B., Kreidl, T.J., Skiff, B.A. and Tombaugh, C.W., 1990, PASP,
   102, 1321 [BIBCODE 1990PASP..102.1321L ]
Mattei, J., 1993, private communication
Szkody, P., 1987, ApJ. Suppl., 63, 685 [BIBCODE 1987ApJS...63..685S ]
Szkody, P., Hoard, D.W., Patterson, J., Moulden, M., Howell, S.B. and Garnavich, P.,
   1993, ASP Conference Series, Vol. 56 [BIBCODE 1994ASPC...56..350S ]
Szkody, P., Howell, S.B., Mateo, M. and Kreidl, T.J., 1989, PASP, 101, 899 [BIBCODE 1989PASP..101..899S ]