Ronald H. Kaitchuck

An atlas of Doppler emission-line tomography of cataclysmic variable stars

Doppler emission-line tomography is a technique similar to medical tomography. In this atlas the emission-line profiles of cataclysmic variable stars, seen at different orbital phases, are transformed into velocity space images. This transformation makes many of the complex line profile changes easier to interpret. The emission contributions of the disk and the s-wave are clearly separated in these images, and any emission from the stream and the secondary star can often be identified. In this atlas, Doppler tomograms of Hbeta, He I lambda 4471, and He II lambda 4686 emission lines of 18 cataclysmic variable stars are presented. The Doppler images provide insights into the individual systems and a better technique for measuring and radial velocity amplitude of the white dwarf.

A SURVEY FOR TRANSIENT ACCRETION DISKS IN SHORT-PERIOD ALGOL SYSTEMS.II.

Time-resolved spectroscopy during primary eclipse was utilized in order to search for emission lines from accretion disks surrounding the primary component in short-period Algol systems. The authors present the results of observations of 46 systems surveyed during 80 eclipses. When combined with an earlier survey this makes a total of 52 systems and 104 eclipses. A distinction is made between the disks in long-period systems and those in short-period systems. In the former case the gas stream from the secondary star moves around the trailing hemisphere of the primary and forms a permanent disk. However, in the latter case the gas stream strikes the primary star. Disks formed by this latter process are found to be transient and unstable. The authors report the discovery of two new transient disk systems: RW Mon and RR Dra. When the relative radius of the primary star is plotted versus mass ratio, the systems with permanent disks, transient disks, and without disks segregate into three distinct regions of the plot. This implies that the differences between systems with transient disks and those without disks may be simply a matter of the location of the stream impact on the primary star.

Atlas of time-resolved spectrophotometry of cataclysmic variables

Whole-orbit, time-resolved spectrophotometry of 18 cataclysmic variables is reduced and displayed in a homogeneous fashion. Each set of digital data is binned into a phase-dependent gray-scale image which resembles a single-trailed photographic spectrogram. This technique permits convient comparison of phase-dependent spectral changes among the different systems. The approximate wavelength interval 4250-4950 A was observed at 2.5 A resolution. This interval contains the accretion disk emission lines of H-beta, H-gamma, He I 4471 A, and He II 4686 A. A brief commentary on the phenomena that can be seen in the image of each star is given. These effects include orbital motion, line-profile changes during eclipse, and s-waves. Several epochs of data on UX UMa are presented, displaying yearly changes in the spectrum. A series of outburst spectra of RX And are included, showing how phase-dependent spectra evolve during outburst. EX Hya spectra are displayed folded on both the 98 minute and the 67 minute photometric periods. In all, 23 spectral data sets are displayed and discussed for the 18 systems. 53 references.

Quantitative spectral types for 19 Algol secondaries

Time-resolved spectra of 19 short-period Algol-type binary star systems obtained during total eclipse used to derive the temperature spectral class of the mass-losing secondary component. The spectral classifications employed a quantitative comparison of the strengths of absorption features in stars of known spectral class with those of the program stars. The luminosity spectral class cannot be determined from these data, so both main sequence and giant stars were used for the comparison. Our spectral types are compared with published types and found to be generally in good agreement, unless the published types are derived from the light curves. The photometrically-detemrined types are systematically later than our directly-determined types. This effect is shown to also exist in catalogs of Algol parameters.

Spectroscopy of the Cataclysmic Variable UU Aquarii: s-Waves and Bright Spots

This paper reports the results of UV and optical spectroscopy of the nova-like variable UU Aqr. There is a decrease in the light flux of both the optical and UV emission lines at phase ~0.95. This appears to be due to an occultation of an asymmetric accretion disk. The emission-line profiles seem to show the first half of the rotational disturbance of the disk eclipse. There is a secondary eclipse at phase 0.4 in the optical continuum and the hydrogen emission lines. It is not present in the UV continuum or emission lines. This eclipse occurs when the bright spot is at superior conjunction. This raises the possibility that this is an occultation of the bright spot/s-wave region by material suspended above the central disk. The accretion disk emission in the Doppler tomogram of the Hβ emission line was used to obtain the radial velocity amplitude of the white dwarf star. The mass ratio was estimated by matching the s-wave position with stream trajectories. The results were significantly different from that of Baptista et al. These authors used the eclipse phasing of the continuum hot spot and the assumption that the hot spot is located on the stream trajectory. The reasons for this discrepancy are unclear.

HL Canis Majoris in preoutburst and SS Cygni - The interoutburst disk instability

SS Cygni and HL Canis Majoris were observed by IUE for three consecutive nights in November of 1992. During the first two nights, simultaneous photometric ground-based observations of SS Cyg were made at the Ball State University Observatory. Observations of SS Cyg and HL CMa were also obtained simultaneously with the 90-inch telescope at the Steward Observatory on the last two nights of the IUE run. These spectroscopic observations covered the wavelength range from 4100 A to 5000 A, while the spectra taken with the short wavelength camera on IUE resulted in wavelength coverage from 1150 A to 1980 A. SS Cyg is a U Gem type dwarf nova with an orbital period of 6.6 hours. Good simultaneous UV and optical orbital coverage was obtained for this system. HL CMa is a Z Cam type dwarf nova with a mean outburst interval of 15 days. The AAVSO reports that this system was in outburst 4 days after the observing run. Therefore, HL CMa may have been in a preoutburst state during these observations. Optical spectra of HL CMa indicate a warm front passed through the outer disk four days before outburst, but no changes were seen in the UV spectra. Signs of a preoutburst state were observed to develop in SS Cyg, but no outburst occurred for another 30 days.

Spectroscopy of the dwarf nova RX Andromedae from quiescence to eruption

The time-resolved spectroscopy of RX And is presented over six consecutive nights from quiescence and into eruption. The radial velocity curve seen in quiescence was highly distorted, as reported earlier. However, this distortion does not appear to be the result of an s-wave, because it persists even when the line core is excluded from the profile fit. Also, it is seen in the outburst absorption lines, indicating that the source of the distortion extends over the entire visible disk. The accretion disk may have started changing at least 14 hr prior to the start of the optical outburst as seen in the emission-line widths and strengths. After the outburst began, the optically thin regions of the disk became totally ionized and all normal Balmer disk emission was replaced by line emission from two new locations: possibly a shell or the heated face of the secondary star and the L3 point. An expansion of the disk is implied in order to force the gas over the L3 potential barrier. Such a disk expansion is consistent with the predictions of the thermal disk instability theory of dwarf nova eruptions. 37 references.

NOVA SERPENTIS 1983.

A spectrum of Nova Serpentis 1983 has been obtained using the IIDS spectrograph attached to the 2.1-meter telescope at Kitt Peak. A series of 10 spectra were co-added to produce a single spectrum covering the wavelengths in the range 4250-4950 A. The integration time was 300 seconds using an 8.4 arcsec aperture. The photometric and spectroscopic characteristics of the spectrum are discussed in detail. A table listing the spectral line emission intensities of H-beta, H-gamma, and N III in the spectrum of Nova Serpentis 1983 is given, and the photometric light curve is reproduced in graphic form.