The Dwarf Nova Outbursts of Nova Her 1960 (=V446 Her)

V446 Her is the best example of an old nova which has developed dwarf nova eruptions in the post-nova state. We report on observed properties of the long-term light curve of V446 Her, using photometry over 19 years. Yearly averages of the outburst magnitudes shows a decline of ~0.013 mag/yr, consistent with the decline of other post-novae that do not have dwarf nova outbursts. Previous suggestions of bimodal distributions of the amplitudes and widths of the outbursts are confirmed. The outbursts occur at a mean spacing of 18 days but the range of spacings is large (13-30 days). From simulations of dwarf nova outbursts it has been predicted that the outburst spacing in V446 Her will increase as M-dot from the red dwarf companion slowly falls following the nova; however the large intrinsic scatter in the spacings serves to hide any evidence of this effect. We do find a systematic change in the outburst pattern in which the brighter, wider type of outbursts disappeared after late 2003, and this phenomenon is suggested to be due to falling M-dot following the nova.Comment: To appear at the Astronomical Journal; 7 pages, 1 table, 11 figure

Observations of V592 Cas -— an Outflow at Optical Wavelengths

We present new red optical spectra of V592 Cas aimed at exploring the properties of the outflow of this system in a spectral region where the underlying white dwarf and the accretion disk do not contribute significantly to the observed absorption components of the Hα and He I line profiles. We use the Hα emission line to study the wind, which appears as pronounced blueshifted P Cygni absorption troughs whose low velocity end contaminates the blue side of the emission line profile. The wind appears to be episodic in nature, with multiple events reaching velocities of 5000 km s^–1 in Hα. Similar (but weaker) wind signatures appear in the He I 5876 Å line but are absent in He I 6678 Å. Our data suggest that during wind episodes the wind is phase dependent and is visible for half of the orbit of the system. Considering that V592 Cas is viewed almost face-on, the symmetry axis of the outflow cannot be orthogonal to the disk and/or the outflow must have some other inherent asymmetry in outflow geometry. A possible origin of the wind is in a disk hotspot, either at the initial impact point of the accretion stream on the disk edge or as a result of disk overflow (similar to SW Sextantis stars). Simultaneous optical photometry during one night of our spectroscopic observations indicate that there is no clear relationship between the optical brightness variations and the strength of the outflow in this system

Orbit-resolved photometry and echelle spectroscopy of the cataclysmic variable ST LMi during a 2007 high state

We present high-resolution echelle spectra and contemporaneous photometry of the polar ST LMi during a high state in 2007 March. Emission lines at Hα, He I λ5876, and He I λ7065 show similar line profiles over orbital phase and have narrow and broad components. These profile changes with phase are very similar to those reported in earlier high-state studies of ST LMi. The radial velocity curves from double Gaussian fits to the line profiles are interpreted as two crossing curves, neither of which is coincident with the orbital motion of the secondary star. We attribute one component to infall motions near the white dwarf and the other to a gas streaming along magnetic field lines connecting the two stars

Evidence for an accretion steam in the low-accretion-rate polar J2048

We present new red/near-infrared spectra of the low-accretion-rate polar J204827.9+005008.9. Compared to 2004 spectra in the literature, our 2008 data show more structured emission-line profiles. All emission lines in our spectra have two components at most orbital phases. The stronger component has a sinusoidal velocity variation (K~ 120 km s^(−1)) and is likely due to irradiation of the inner hemisphere of the secondary star by the white dwarf. Based on the appearance of the Hα Doppler tomogram, the weaker, larger amplitude, line component likely originates in a ballistic stream from the L1 point. J2048 is thought to be accreting via a wind from the secondary star, so the detection of velocity features consistent with the velocities of Roche lobe overflow is unexpected. It appears that J2048 was experiencing an interval of enhanced mass transfer during our observations. We briefly discuss scenarios that might lead to such a situation, such as changes in the chromospheric activity level on the secondary star

The Long-Period Orbit of the Dwarf Nova V630 Cassiopeiae

We present extensive spectroscopy and photometry of the dwarf nova V630 Cassiopeiae. A late-type (K4-5) absorption spectrum is easily detectable, from which we derive the orbital parameters. We find a spectroscopic period of P=2.56387 +/- (4 times 10^{-5}) days and a semiamplitude of K_2=132.9 +/- 4.0 km/s. The resulting mass function, which is a firm lower limit on the mass of the white dwarf, is then f(M)=0.624 +/- 0.056 solar masses. The secondary star is a ``stripped giant\u27\u27, and using relations between the core mass and the luminosity and the core mass and the radius we derive a lower limit of M_2 \u3e 0.165 solar masses for the secondary star. The rotational velocity of the secondary star is not resolved in our spectra and we place a limit of V_rot*sin(i) \u3c 40 km/s. The long-term light curve shows variations of up to 0.4 mag on short (1-5 days) time scales, and variations of 0.2-0.4 mag on longer (3-9 months) time scales. In spite of these variations, the ellipsoidal light curve of the secondary star is easily seen when the data are folded on the spectroscopic ephemeris. Ellipsoidal models fit to the mean light curve give an inclination in the range 66.96 \u3c i \u3c 78.08 degrees (90 per cent confidence). This inclination range, and the requirement that M_2 \u3e 0.165 solar masses and V_rot*sin(i) \u3c 40 km/s yields a white dwarf mass of M_1=0.977^{+0.168}_{-0.098} solar masses and a secondary star mass of M_2=0.172^{+0.029}_{-0.012} solar masses (90 per cent confidence limits). Our findings confirm the suggestion of Warner (1994), namely that V630 Cas is rare example of a dwarf nova with a long orbital period

QU Carinae: a SNeIa progenitor?

Optical spectra obtained in 2006-07 of the nova-like cataclysmic variable QU Car are studied for radial velocities, line profiles, and line identifications. We are not able to confirm the reported 10.9 hr orbital period from 1982,partly because our sampling is not ideal for this purpose and also, we suspect, because our radial velocities are distorted by line profile changes due to an erratic wind. P-Cygni profiles are found in several of the emission lines, including those of C IV. Carbon lines are abundant in the spectra, suggesting a carbon enrichment in the doner star. The presence of [O III] 5007\AA and [N II] 6584\AA is likely due to a diffuse nebula in the vicinity of the system. The wind signatures in the spectra and the presence of nebular lines are in agreement with the accretion wind evolution scenario that has been suggested to lead to SNeIa. We argue that QU Car is a member of the V Sge subclass of CVs, and a possible SNeIa progenitor. It is shown that the recent light curve of QU Car has ~1 mag low states, similar to the light curve of V Sge, strengthening the connection of QU Car with V Sge stars, supersoft x-ray sources, and SNeIa progenitors.Comment: Accepted in the Astronomical Journal. 11 pages, 3 tables, 5 figure

Spectroscopic and Photometric Analysis of the Nova-Like Cataclysmic Variable PG 1000+667: A New VY Sculptoris Star

Multiyear photometry and orbit-resolved spectroscopy of the nova-like cataclysmic variable PG 1000+667 show behavior associated with the VY Sculptoris subclass of nova-like cataclysmic variables. Photometric observations over a 35 month interval from Indiana University\u27s robotic telescope Robo-Scope show two drops of 3 mag to a low state. Spectroscopy shows a periodic velocity variation in the Hβ emission line with P = 3.47 hr. This places the star just above the 2-3 hour period gap, which supports the VY Sculptoris classification

SPECTROSCOPIC STUDY OF Q CYGNI: SURPRISES FROM AN OLD NOVA

We present a time-resolved spectroscopic study of Q Cyg (Nova Cyg 1876), determining a period of P = 10.08 hr for the system. Our data also reveal P Cygni profiles in the He I λλ5876 and 7065 lines and occasionally in the Hα line. Although P Cygni profiles commonly appear in the UV resonance lines of novalike cataclysmic variables, only BZ Cam was previously known to exhibit a rapidly variable wind, which leaves its signature in time-resolved optical spectral lines. A comparison between BZ Cam and Q Cyg reveals striking similarities between the two systems. The origin of the outflow in Q Cyg and a possible correlation of the P Cygni profiles with the system's optical state are discussed