The hydrogen-rich envelopes accreted by white dwarf stars from their red dwarf companions lead to thermonuclear runaways observed as classical nova eruptions peaking at up to 1 Million solar luminosities. Virtually all nova progenitors are novalike binaries exhibiting high rates of mass transfer to their white dwarfs before and after an eruption. It is a puzzle that binaries indistinguishable from novalikes, but with much lower mass transfer rates, and resulting dwarf nova outbursts, co-exist at the same orbital periods. Nova shells surrounding several dwarf novae demonstrate that at least some novae become dwarf novae between successive nova eruptions, though the mechanisms and timescales governing mass transfer rate variations are poorly understood. Here we report simulations of the multiGyr evolution of novae which self-consistently model every eruption's thermonuclear runaway, mass and angular momentum losses, feedback due to irradiation and variable mass transfer, and orbital size and period changes. The simulations reproduce the observed wide range of mass transfer rates at a given orbital period, with large and cyclic changes in white dwarf-red dwarf binaries emerging on kyr to Myr timescales. They also demonstrate that deep hibernation, (complete stoppage of mass transfer for long periods), occurs only in short-period binaries; that initially very different binaries converge to become nearly identical systems; that while almost all prenovae should be novalike binaries, dwarf novae should also occasionally be observed to give rise to novae; and that the masses of white dwarfs decrease only slightly while their red dwarf companions are consumed.
We report simultaneous observations of the flaring behaviour of the cataclysmic variable star AE Aqr. The observations are in Johnson B and V bands. The colour-magnitude diagrams (B-V versus V and B-V vs. B) show that the star becomes blues as it becomes brighter. In our model AE Aqr behaviour can be explained with flares (fireballs) with 0.03 < B-V < 0.30 and temperature in the interval 8000 < T < 12000.
The publicly available WASP data are analysed to determine the orbital periods of the cataclysmic variables V378 Peg, SDSS J171456.78+585128.3 and ASAS 150946-2147.7.
Cataclysmic Variables (CVs) are interacting binaries consisting of at least three components that control their colour and magnitude. Using Gaia we here investigate the influence of the physical properties of these binaries on their position in the Hertzsprung-Russell diagram (HR-diagram). The CVs are on average located between the main sequence and the white dwarf regime, the maximum density being at $G_{BP}-G_{RP} \sim 0.56$ and $G_{abs} \sim 10.15$. We find a trend of the orbital period with colour and absolute brightness: with decreasing period, the CVs become bluer and fainter. We also id…
We present differential photometry of the cataclysmic variable star SW Sextantis. A time series analysis was performed in search of superhumps in the accretion disk of this star, which is the prototype of a class of cataclysmic variables, the SW Sex stars. We find no superhumps, which shows that the presence of superhumps is not a defining feature of the SW Sex stars.
We report on the photometric analysis of the poorly studied cataclysmic variable in Ophiuchus 1RXS J174320.1-042953 (DDE 11). Results of the monitoring with the Bradford Robotic Telescope (BRT) are presented, as well as the time-resolved photometry obtained at Montecatini Astronomical Centre. The long-term behavior of J1743-0429 shows it is a magnetic cataclysmic variable (polar) with the large difference between the low and high states. The orbital period obtained from our observations is 0.0866d, or 2.08hr, close to the lower boundary of the period gap of cataclysmic variables.
Spiral density waves are thought to be excited in the accretion discs of accreting compact objects, including Cataclysmic Variable stars (CVs). Observational evidence has been obtained for a handful of systems in outburst over the last two decades. We present the results of a systematic study searching for spiral density waves in CVs, and report their detection in two of the sixteen observed systems. While most of the systems observed present asymmetric, non-Keplerian accretion discs during outburst, the presence of ordered structures interpreted as spiral density waves is not as ubiquitous as…
Despite being bright ($V=12$) and nearby ($d=212$ pc) ASAS J071404+7004.3 has only recently been identified as a nova-like cataclysmic variable. We present time-resolved optical spectroscopy obtained at the Isaac Newton Telescope together with $\textit{Swift}$ X-ray and ultraviolet observations. We combined these with $\textit{TESS}$ photometry and find a period of 3.28h and a mass transfer rate of $4-9 \times 10^{-9} M_{sun}/yr$. Historical photometry shows at least one low state establishing the system as a VY Scl star. Our high-cadence spectroscopy also revealed rapidly changing winds emana…
We report detailed follow-up observations of 8 cataclysmic variable stars (CVs) that are apparently AM Her stars, also called polars. For all, we either determine orbital periods for the first time, or improve on existing determinations. The seven for which we have spectra show the high-amplitude radial velocity curves and prominent HeII 4686 emission lines characteristic of strongly magnetic CVs, and their periods, which range from 81 to 219 minutes, are also typical for AM Her stars. Two objects from the Gaia-alerts index, Gaia18aot and Gaia18aya, are newly identified as CVs. Another, RX J06…
It has been shown that the rate of angular momentum loss (AML) in cataclysmic variables (CVs) below the period gap is about 2.47 times that caused by gravitational radiation, suggesting extra AML mechanism besides gravitational radiation. Several potential mechanisms have been proposed but none of them has been verified. In this work we examine whether AML caused by friction between the expanding nova envelope and the donor star can account for the required AML rate. By adopting various expanding velocities of the envelope, we have calculated the evolution of CVs with typical initial parameter…
We present a study of the cataclysmic variable star PT Per based on archival XMM-Newton X-ray data and new optical spectroscopy from the WHT with ISIS. The X-ray data show deep minima which recur at a period of 82 minutes and a hard, unabsorbed X-ray spectrum. The optical spectra of PT Per show a relatively featureless blue continuum. From an analysis of the X-ray and optical data we conclude that PT Per is likely to be a magnetic cataclysmic variable of the polar class in which the minima correspond to those phase intervals when the accretion column rotates out of the field of view of the obs…
We report on XMM-Newton and optical results for 6 cataclysmic variables that were selected from Sloan Digital Sky Survey spectra because they showed strong HeII emission lines, indicative of being candidates for containing white dwarfs with strong magnetic fields. While high X-ray background rates prevented optimum results, we are able to confirm SDSSJ233325.92+152222.1 as an intermediate polar from its strong pulse signature at 21 min and its obscured hard X-ray spectrum. Ground-based circular polarization and photometric observations were also able to confirm SDSSJ142256.31-022108.1 as a pol…
We explore the observational appearance of the merger of a low-mass star with a white dwarf (WD) binary companion. We are motivated by Schreiber et al. (2016), who found that multiple tensions between the observed properties of cataclysmic variables (CVs) and standard evolution models are resolved if a large fraction of CV binaries merge as a result of unstable mass transfer. Tidal disruption of the secondary forms a geometrically thick disk around the WD, which subsequently accretes at highly super-Eddington rates. Analytic estimates and numerical hydrodynamical simulations reveal that outflo…
PHL 1445 is found to be an eclipsing cataclysmic variable with an orbital period of 76.3 minutes. GALEX J003535.7+462353 is a new eclipsing dwarf nova with an orbital period of 4.13 hours. Both objects show deep eclipses with an amplitude of more than two magnitudes.
We present four nights of time-resolved photometry of the cataclysmic variable star HV And. Our time series analysis has revealed a prominent period at 3.368 +/- 0.060 hours, as well as some low frequency power. We interpret this signal, from saw-tooth waves in the light curve, as evidence of superhumps in HV And.
From recent large observing campaigns, one finds that nearly all non- or weakly magnetic cataclysmic variables in the orbital period range between 2.8 and 4 hours are of SW Sex type and as such experience very high mass transfer rates. The evolution of cataclysmic variables as for any interacting binary is driven by angular momentum loss which results in a decrease of the orbital period on evolutionary time scales. In particular, all long-period systems need to cross the SW Sex regime of the orbital period distribution before entering the period gap. This makes the SW Sex phenomenon an evoluti…
As a result of applying the original optical variability search method on publicly available data, we have found eight new cataclysmic variables and two possible Optically Violent Variable quasars among the previously unidentified X-ray sources in the ROSAT catalog. We describe the search method and present the characteristics of the newly identified variable stars. The obtained results demonstrate the large potential of the concept of Virtual Observatory for identifying new objects of astrophysical interest.
Results of photometric and spectroscopic investigations of the recently discovered disc cataclysmic variable star 1RXS J180834.7+101041 are presented. Emission spectra of the system show broad double peaked hydrogen and helium emission lines. Doppler maps for the hydrogen lines demonstrate strongly non-uniform emissivity distribution in the disc, similar to that found in IP Peg. It means that the system is a new cataclysmic variable with a spiral density wave in the disc. Masses of the components (M_WD = 0.8 +/- 0.22 M_sun and M_RD = 0.14 +/- 0.02 M_sun), and the orbit inclination (i = 78 +/- …
In course of the search for the optical identifications associated with ROSAT X-ray sources we have found a highly variable object with the very unusual long-term behavior, color indices and high X-ray-to-optical flux ratio. We report the archival photometric light curve from the Catalina Sky Survey, optical spectroscopy from RTT150 and time-resolved photometry from Astrotel-Caucasus telescope. The object appears to be the magnetic cataclysmic variable (polar) with orbital period of P=3.20 hr.
Cataclysmic variables are among the photometrically most unstable stars in the zoo of stellar objects, exhibiting light variations on all time-scales between millennia and seconds. The literature is full of reports on variable phenomena which often require independent confirmation before they can be accepted as established facts. In this contribution I investigate accounts on miscellaneous variable features observed in six cataclysmic variables, drawing for this purpose largely on archival data, most of which have not been investigated in detail in the past, and complementing these data with s…
The Palomar Transient Factory proves to be a prolific source of Magnetic Cataclysmic Variables, selected by their distinctive photometric variability, and followed up spectroscopically. Here, we present six new candidate systems, together with preliminary photometric periods and spectra.
The detection of heavy elements at suprasolar abundances in the atmospheres of some accreting white dwarfs in cataclysmic variables, coupled with the high temperatures needed to produce these elements requires explosive thermonuclear burning. The central temperatures of any formerly more massive secondary stars in CVs undergoing hydrostatic CNO burning are far too low to produce these elements. Evidence is presented that at least some cataclysmic variables contain donor secondaries that have been contaminated by repeated novae ejecta and are transferring this material back to the white dwarf. …
To mark the half-century anniversary of this newly-born field of Cataclysmic Variables, a special emphasis is made in this review, on the Doppler Effect as a tool in astrophysics. The Doppler Effect was in fact, discovered almost 170 years ago, and has been since, one of the most important tools which helped to develop modern astrophysics. We describe and discuss here, its use in Cataclysmic Variables which, combined with another important tool, the tomography, first devised for medical purposes 70 years ago, helped to devise the astronomical Doppler Tomography, developed only two decades ago.…
We present the results of our photometric and spectroscopic studies of the new eclipsing cataclysmic variable star 1RXS J180834.7+101041. Its spectrum exhibits double-peaked hydrogen and helium emission lines. The Doppler maps constructed from hydrogen lines show a nonuniform distribution of emission in the disk similar to that observed in IP Peg. This suggests that the object can be a cataclysmic variable with tidal density waves in the disk. We have determined the component masses (M_WD =0.8 \pm 0.22 M_sun and M_RD =0.14 \pm 0.02 M_sun) and the binary inclination (i =78 \pm 1.5 deg) based on…
We present high-speed photometry covering one eclipse of the cataclysmic variable system 1RXS J180834.7+101041. The data are modelled as arising from a close binary system containing a low-mass stars filling its Roche lobe plus a white dwarf with an accretion disc. We find an orbital inclination of 77.07 +/- 0.47 degrees and a mass ratio of 0.168 +/- 0.016. The relatively low inclination means that only the accretion disc and not the white dwarf are eclipsed by the low-mass star in this system.
Every massive globular cluster (GC) is expected to harbour a significant population of cataclysmic variables (CVs). In this review, I first explain why GC CVs matter astrophysically, how many and what types are theoretically predicted to exist and what observational tools we can use to discover, confirm and study them. I then take a look at how theoretical predictions and observed samples actually stack up to date. In the process, I also reconsider the evidence for two widely held ideas about CVs in GCs: (i) that there must be many fewer dwarf novae than expected; (ii) that the incidence of ma…
We present results of our spectroscopic campaign dedicated to the ultracompact binary ES Ceti. On the nights 2002 Oct. 27-28, 528 spectra were taken with the 6.5-meter telescope in Las Campanas Observatory in Chile. The averaged spectrum shown the double-peaked helium emission lines which imply the presence of an accretion disk in this system.
We report on our second campaign to search for old nova shells around cataclysmic variables (CVs). Our aim was to test the theory that nova eruptions cause cycles in the mass transfer rates of CVs. These mass transfer cycles change the behaviour of CVs during their inter-eruption periods. We examined H-alpha images of 47 objects and found no new shells around any of the targets. Combining our latest results with our previous campaign (Sahman et al. 2015), and the searches by Schmidtobreick et al. (2015) and Pagnotta & Zurek (2016), we estimate that the nova-like phase of the mass transfer cycl…
Cataclysmic variable SDSS J143317.78+101123.3 with P=0.054241 d (78.1-min) was suspected to be a possible dwarf nova of WZ Sge type with the sub-stellar donor, but without detected outbursts so far. Checking the newly available data from ATLAS survey has revealed the outburst by at least 6 magnitudes in September 2020, thus confirming the dwarf nova nature of this object with the brown dwarf secondary. Other projects and individual observers have stopped their monitoring of this target several days before the outburst. This finding strengthens the value of observing the twilight zone by the pr…
We report the discovery of a new cataclysmic variable in MASTER database which is identical to the faint ROSAT X-ray source 1RXS J015017.0+375614. The object was observed in outbursts to 14.9m on 2012 Nov. 28 and to 14.3m on 2013 Jan. 07, but not detected in course of the routine real-time search. Analysis of the archival MASTER data and CRTS light curve shows the large-amplitude variability from 19.1m at quiescence to 15.4-14.8m in outbursts. The new variable is most likely a dwarf nova of SU UMa subtype with rather frequent normal outbursts and occasional superoutbursts.
The cataclysmic variable SDSS154453+2553 was recently identified in the Sloan Digital Sky Survey. We obtained spectra and photometry at the MDM Observatory, which revealed an eclipse with a 6.03 hour period. The Hα emission line exhibits a strong rotational disturbance during eclipse, indicating that it arises in an accretion disk. A contribution from an M-type companion is also observed. Time-series photometry during eclipse gives an ephemeris of 2454878.0062(15) + 0.251282(2)E. We present spectroscopy through the orbit and eclipse photometry. Our analysis of the secondary star indicates a di…
MASTER OT J190519.41+301524.4 was discovered as an optical transient of 15.7m by the Mobile Astronomical System of TElescope-Robots in March 2014. We report the results of photometric observations of this variable performed at Lajatico Astronomical Center in June-July 2015. The light curve is showing deep V-shaped eclipses with an amplitude of two magnitudes. The orbital period was determined to be 0.129694 d (3.113 h). Based on the archival observations and the shape of the orbital curve we suggest that MASTER OT J190519.41+301524.4 is a new cataclysmic variable of VY Scl type ("anti-nova") w…
I report on the discovery of two cataclysmic variables in the same field in Lyra originally identified from their magnitudes in USNO-B1.0 catalogue and Palomar images. The historical light curves were analyzed on 300+ photographic plates from Moscow collection covering 35 years of observations. One of two stars, USNO-B1.0 1320-0390658, is showing rather frequent outbursts from B~20 to B=15.2 and is likely a dwarf nova of UGSS subtype. The other variable, USNO-B1.0 1321-0397655, has only one observed outburst in 1993 from R~19 to I=11.8 and is either a UGWZ dwarf nova or a recurrent nova. In bo…
We report time-resolved photometry of the cataclysmic variable V849 Her, and measure a period of 0.1414 \pm 0.0030 days (3.394 \pm 0.072 hours). We also present photometry taken over several weeks in 2010 and 2011, as well as light curves from 1995 to 2011 by the American Association of Variable Star Observers. The spectra, absolute magnitude derived from infrared magnitudes, and variability all suggest that V849 Her is a nova-like variable. The shallow (0.5-magnitude) low states we observe resemble the erratic low states of the VY Sculptoris stars, although they may recur quasi-periodically o…
I performed photometric observations of the poorly studied cataclysmic variable IPHAS J013031.89+622132.3 and discovered very deep eclipses. I obtained observations over 14 nights for a total time of 50 hours during a time span of 6 months. Thanks to the long observation interval, I determined the orbital period with high precision, Porb=0.14935014+/-0.00000020 d. I derived the eclipse ephemeris, which, thanks to the precision of the orbital period, has a formal validity of 300 years. The average eclipse depth was 1.88+/-0.07 mag. The prominent parts of the eclipses were smooth and symmetrical…
The origin of magnetic fields in isolated and binary white dwarfs has been investigated in a series of recent papers. One proposal is that magnetic fields are generated through an alpha-omega dynamo during common envelope evolution. Here we present population synthesis calculations showing that this hypothesis is supported by observations of magnetic binaries.
We measured the photometric flux of the cataclysmic variable TT Arietis (BD+14 341) using the MOST space telescope. Periodic oscillations of the flux reveal the orbital period as well as other features of this binary system. We applied a Discrete Fourier Transform (DFT) on a reduced dataset to retrieve the frequencies of TT Arietis. The analysis of the system revealed a photometric period of 3.19 hours. Though the MOST data has a high cadence of 52.8 seconds, a fine structure of the accretion disk is not obvious.
We report the discovery of a new cataclysmic variable MASTER OT J161700.81+620024.9 which is identical to the faint ROSAT X-ray source 1RXS J161659.5+620014. The object was observed in outbursts to 14.4m on 2012 Sep. 11 by MASTER-Tunka and to 14.3m on 2013 Jan. 21/22 by MASTER-Kislovodsk, but was not detected by the routine search procedures. Analysis of the archival MASTER data and CRTS light curve shows the variability from 17.8m at quiescence to 14.3m in outbursts, confirming that the new variable is a dwarf nova. SDSS colors suggest a small contribution from the secondary component and are…
The search was performed for cataclysmic variable stars with outlying infrared magnitudes in USNO-B1.0 catalog. The selection was limited to objects in the Northern hemisphere with (B1-R1) < 1 and (R2-I) > 3.5. The search method is described, and the details on individual stars are given. In total 27 variable objects were found with 20 being the previously known ones and 7 - new discoveries. 4 of newly found variables are dwarf novae, while the remaining 3 - pulsating red variables of Mira or semi-regular types, including a heavily reddened one in Pelican nebula. The correct pulsation period i…
The NASA {\it Kepler} mission has been in science operation since May 2009 and is providing high precision, high cadence light curves of over 150,000 targets. Prior to launch, nine cataclysmic variables were known to lie within {\it Kepler's} field of view. We present spectroscopy for seven systems, four of which were newly discovered since launch. All of the stars presented herein have been observed by, or are currently being observed by, the {\it Kepler} space telescope. Three historic systems and one new candidate could not be detected at their sky position and two candidates are called int…
Spectra of 38 candidate or known cataclysmic variables are presented. Most are candidate dwarf novae or systems containing possible highly magnetic white dwarfs, while a few (KR Aur, LS Peg, V380 Oph and V694 Mon) are previously known objects caught in unusual states. Individual spectra are used to confirm a dwarf nova nature or other classification while radial velocities of 15 systems provide orbital periods and velocity amplitudes that aid in determining the nature of the objects. Our results substantiate a polar nature for four objects, find an eclipsing SW Sex star below the period gap, a…
We present the nine-year light curve of the cataclysmic variable 1RXS J140429.5+172352 from 2005 April to 2014 July. We identified four dwarf nova-like outbursts, which typically lasted 3 to 5 days, with an amplitude of 3.1 to 5.3 magnitudes. Time resolved photometry during two outbursts revealed small hump-like structures with peak-to-peak amplitude up to 0.5 mag. They occurred on timescales of 20 min to an hour, but did not exhibit a stable period. We suggest that the system might be an Intermediate Polar.
The flow structure in magnetic cataclysmic variables was investigated taking into account the effects of strong magnetic field and fast rotation of the white dwarf. We modeled the AE Aqr system as a unique object that has the rotation period of the white dwarf is about 1000 times shorter than the orbital period of the binary system. Observations show that in spite of fast rotation of the white dwarf some part of the stream from the inner Lagrange point comes into the Roche lobe region. We analyzed possible mechanisms preventing material to outflow from the system.
We have discovered a new high proper motion cataclysmic variable (CV) in the SUPERBLINK proper motion survey, which is sensitive to stars with proper motions greater than 40 mas/yr. This CV was selected for follow-up observations as part of a larger search for CVs selected based on proper motions and their NUV-V and V-K$_{s}$ colors. We present spectroscopic observations from the 2.4m Hiltner Telescope at MDM Observatory. The new CV's orbital period is near 96 minutes, its spectrum shows the double-peaked Balmer emission lines characteristic of quiescent dwarf novae, and its V magnitude is nea…
The population of cataclysmic variables with orbital periods right above the period gap are dominated by systems with extremely high mass transfer rates, the so-called SW Sextantis stars. On the other hand, some old novae in this period range which are expected to show high mass transfer rate instead show photometric and/or spectroscopic resemblance to low mass transfer systems like dwarf novae. We discuss them as candidates for so-called hibernating systems, CVs that changed their mass transfer behaviour due to a previously experienced nova outburst. This paper is designed to provide input fo…
In a series of recent papers, it has been proposed that high field magnetic white dwarfs are the result of close binary interaction and merging. Population synthesis calculations have shown that the origin of isolated highly magnetic white dwarfs is consistent with the stellar merging hypothesis. In this picture, the observed fields are caused by an alpha-Omega dynamo driven by differential rotation. The strongest fields arise when the differential rotation equals the critical break-up velocity and result from the merging of two stars (one of which has a degenerate core) during common envelope…
We performed simultaneous observations in 3 bands (UBV) of the flickering variability of the recurrent novae RS Oph and T CrB at quiescence. Using new and published data, we compare the colours of the flickering in cataclysmic variables and symbiotic recurrent novae. We find a difference between the colours of the flickering source in these two types of accreting white dwarfs. The detected difference is highly significant with $ p-value \approx 2 \times 10^{-6}$ for the distributions of $(U-B)_0$ colour and $p \approx 3 \times 10^{-5}$ on (U-B) versus (B-V) diagram. The possible physical reaso…
The twelve-year light curve of the nova-like cataclysmic variable HS 0506+7725 between 2006 April and 2018 November is presented. This shows that the star spends most of the time in a normal state at magnitude ~14.7, but multiple excursions to a fainter state at magnitude 16.0 to 17.0 were apparent. These normal state/low state transitions of up to 2.3 magnitudes are typical of the VY Scl subclass of CVs. The second of these fading episodes was the best characterised as its return to normal brightness was also observed. The complete transition lasted about 43 days. Further monitoring of this s…
Time series photometry of 20 Cataclysmic Variables detected by the Catalina Real-time Transient Survey is presented. 14 of these systems have not been observed previously and only two have been examined in-depth. From the observations we determined 12 new orbital periods and independently found a further two. Eight of the CVs are eclipsing systems, five of which have eclipse depths of more than 0.9 mag. Included in the sample are six SU UMa systems (three of which show superhumps in our photometry), a polar (SSS1944-42) and one system (CSS1417-18) that displays an abnormally fast decline from …
The Galactic orbital parameters of 159 cataclysmic variables in the Solar neighbourhood are calculated, for the first time, to determine their population types using published kinematical parameters. Population analysis shows that about 6 per cent of cataclysmic variables in the sample are members of the thick disc component of the Galaxy. This value is consistent with the fraction obtained from star count analysis. The rest of the systems in the sample are found to be in the thin disc component of the Galaxy. Our analysis revealed no halo CVs in the Solar vicinity. About 60 per cent of the th…
We study the newly discovered variable star GSC 4560--02157. CCD photometry was performed in 2013--2014, and a spectrum was obtained with the 6-m telescope in June, 2014. GSC 4560--02157 is demonstrated to be a short-period (P=0.265359d) eclipsing variable star. All its flat-bottom primary minima are approximately at the same brightness level, while the star's out-of-eclipse brightness and brightness at secondary minimum varies considerably (by up to 0.6m) from cycle to cycle. Besides, there are short-term (time scale of 0.03-0.04 days) small-amplitude brightness variations out of eclipse. Thi…
Recent observations show that the white dwarfs (WDs) in cataclysmic Variables (CVs) have an average mass significantly higher than isolated WDs and WDs in post-common envelope binaries (PCEBs), which are thought to the progenitors of CVs. This suggests that either the WDs have grown in mass during the PCEB/CV evolution or the binaries with low-mass WDs are unable to evolve to be CVs. In this paper, we calculate the evolution of accreting WD binaries with updated hydrogen accumulation efficiency and angular momentum loss prescriptions. We show that thermal timescale mass transfer is not effecti…
A critical analysis of three methods of estimating distances to cataclysmic variables (CVs) is performed. These methods, by Ak et al., Beuermann, and Knigge, all use near-infrared (JHK or Ks) magnitudes and the Barnes-Evans relation. We compare all three methods to distances measured by trigonometric parallax by Thorstensen, with Hubble Space Telescope, and with the HIPPARCOS spacecraft. We find that the method of Ak et al. works best overall for all CVs, predicting distances on the average 4% less than those measured by trigonometric parallaxes. The method of Beuermann overestimates distances…
We present a study of the recently discovered intermediate polar 1RXS J070407+262501, distinctive for its large-amplitude pulsed signal at P = 480 s. Radial velocities indicate an orbital period of 0.1821(2) d, and the light curves suggest 0.18208(6) d. Time-series photometry shows a precise spin period of 480.6700(4) s, decreasing at a rate of 0.096(9) ms/yr, i.e. on a time scale P/P-dot =2.5 x 10^6 yr. The light curves also appear to show a mysterious signal at P = 0.263 d, which could possibly signify the presence of a "superhump" in this magnetic cataclysmic variable.
The dependencies of the phase of eclipse of the white dwarf's centre and the durations of the ascending and descending branches of the light curve on the binary system's parameters were computed using the spherically-symmetric approximation and the more accurate model of the elliptical projection onto the celestial sphere of the companion (red dwarf) that fills its Roche lobe. The parameters of eclipses in the classical eclipsing polar OTJ 071126+440405 = CSS 081231:071126+440405 were estimated.
