A substantial fraction of Cataclysmic Variables (CVs) reveals non-solar abundances. A comprehensive list of CVs which includes those that have been examined for these abundances is given. Three possible sources of these non-solar abundances on the secondary are accretion during the red giant common envelope phase, an Evolved Main Sequence secondary and nova-processed material. Use of the secondary's cross-section just on the escaping nova material to change the abundances of its convective region has been the killing objection for considering nova-processed material. The key element, ignored in other studies, is that a thermonuclear runaway on a white dwarf causes a strong propagating shock wave which not only ejects material, but also produces a large amount of non-ejected material which forms a common envelope. This nova-produced common envelope contains a large amount of non-solar material. We demonstrate that the secondary has the capacity and time to re-accrete enough of this material to acquire a significant non-solar convective region. This same envelope interacting with the binary will produce a Frictional Angular Momentum Loss which can be the Consequential Angular Momentum Loss needed for the average CV white dwarf mass, WD mass accretion rates, the period minimum, the orbital period distribution, and the space density of CVs problems. This interaction will decrease the orbital period which can cause the recently observed sudden period decreases across nova eruptions. A simple, rapid evolutionary model of the secondary that includes the swept-up nova-produced material and the increasing convective region is developed and applied to individual CVs.
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…
High speed photometry of faint cataclysmic variables - VI. Car2, V1040 Cen, Ha 075648, IL Nor (Nova Nor 1893), HS Pup (Nova Pup 1963), SDSS J2048-06, CSS 081419-005022 and CSS 112634-100210
The unprecedented sky coverage and observing cadence of the All-Sky Automated Survey for SuperNovae (ASAS-SN) has resulted in the discovery and continued monitoring of a large sample of Galactic transients. The vast majority of these are accretion-powered dwarf nova outbursts in cataclysmic variable systems, but a small subset are thermonuclear-powered classical novae. Despite improved monitoring of the Galaxy for novae from ASAS-SN and other surveys, the observed Galactic nova rate is still lower than predictions. One way classical novae could be missed is if they are confused with the much l…
Dwarf Nova Oscillations and Quasi-Periodic Oscillations in Cataclysmic Variables - VIII. VW Hyi in outburst observed with the Southern African Large Telescope
Spectra of 76 known dwarf novae from the LAMOST survey were presented. Most of the objects were observed in quiescence, and about 16 systems have typical outburst spectra. 36 of these systems were observed by SDSS, and most of their spectra are similar to the SDSS spectra. 2 objects, V367 Peg and V537 Peg, are the first to observe their spectra. The spectrum of V367 Peg shows a contribution from a M-type donor and its spectral type could be estimated as M3-5 by combining its orbital period. The signature of white dwarf spectrum can be seen clearly in four low-accretion-rate WZ Sge stars. Other…
The eclipsing novalike cataclysmic variable CRTS SSS100505 J093417-174421
Universidade Federal de Santa Catarina（圣卡塔琳娜联邦大学）；Laboratório Nacional de Astrofísica（国家天体物理学实验室）；Universidade Federal de Sergipe（塞尔希培联邦大学）；Observatório Nacional（国家天文台）；Instituto de Astronomia, Geofísica e Ciências Atmosféricas da USP（圣保罗大学天文、地球物理和大气科学研究所）；Instituto Nacional de Pesquisas Espacias（国家空间研究 institute）；Universidade do Vale do Paraíba（帕拉伊巴河谷大学）；Universidade Estadual Paulista（圣保罗州立大学）
We present a complete dynamical study of the intermediate polar and dwarf nova cataclysmic variable GK Per (Nova Persei 1901) based on a multi-site optical spectroscopy and $R$-band photometry campaign. The radial velocity curve of the evolved donor star has a semi-amplitude $K_2=126.4 \pm 0.9 \, \mathrm{km}\,\mathrm{s}^{-1}$ and an orbital period $P=1.996872 \pm 0.000009 \, \mathrm{d}$. We refine the projected rotational velocity of the donor star to $v_\mathrm{rot} \sin i = 52 \pm 2 \, \mathrm{km}\,\mathrm{s}^{-1}$ which, together with $K_2$, provides a donor star to white dwarf mass ratio $…
High speed photometry of faint Cataclysmic Variables - VII. Targets selected from the Sloan Digital Sky Survey and the Catalina Real-time Transient Survey
Superhumps are among the abundant variable phenomena observed in the light curves of cataclysmic variables (CVs). They come in two flavours as positive and negative superhumps, distinguished by periods slightly longer or shorter, respectively, than the orbital periods of these interacting binary systems. Positive superhumps are ubiquitous in superoutbursting short period dwarf novae of the SU~UMa type but are less common in longer period systems with accretion disks in a permanent bright state such as novalike variables and most old novae. Negative superhumps do not seem not to have a preferen…
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 identification and follow-up of the transient SRG 062340.2-265715 detected with both instruments on board the Spektrum-Roentgen-Gamma mission. Optical spectroscopy of the G=12.5 counterpart firmly classifies the object as a novalike cataclysmic variable (CV) at a distance of 495 pc. A highly significant TESS period of 3.941 hours, tentatively identified with the orbital period of the binary, could not be found when the object was reobserved with TESS two years later. The newer high-cadence TESS data revealed quasi-periodic oscillations around 25 min, while ground-based photometry…
We obtained photometric observations of the nova-like cataclysmic variable RW Tri and gathered all available AAVSO and other data from the literature. We determined the system parameters and found their uncertainties using the code developed by us to model the light curves of binary systems. New time-resolved optical spectroscopic observations of RW Tri were also obtained to study the properties of emission features produced by the system. The usual interpretation of the single-peaked emission lines in nova-like systems is related to the bi-conical wind from the accretion disc's inner part. Ho…
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…
Sudden and Steady Orbital Period Changes Across Six Classical Nova Eruptions; The End of Hibernation and Two Serious Challenges for the Magnetic Braking Model of Cataclysmic Variable Evolution
Flickering is a universal phenomenon in accreting astronomical systems which still defies detailed physical understanding. It is particularly evident in cataclysmic variables (CVs). Attempting to define boundary conditions for models, the strength of the flickering is measured in several thousand light curves of more than 100 CVs. The flickering amplitude is parameterized by the FWHM of a Gaussian fit to the magnitude distribution of data points in a light curve. This quantity requires several corrections before a comparison between different sources can be made. While no correlations of the f…
We report follow-up observations of five cataclysmic variable candidates from LAMOST published by Hou et al. (2020). LAMOST J024048.51+195226.9 is the most unusual of the five; an early-M type secondary star contributes strongly to its spectrum, and its spectral and photometric behavior are strikingly reminiscent of the hitherto-unique propeller system AE Aqr. We confirm that a 7.34-hr period discovered in the Catalina survey data (Drake et al. 2014) is orbital. Another object, LAMOST J204305.95+341340.6 appears to be a near twin of the novalike variable V795 Her, with an orbital period in the…
Modifying the Standard Disk Model for the Ultraviolet Spectral Analysis of Disk-dominated Cataclysmic Variables. I. The Novalikes MV Lyrae, BZ Camelopardalis, and V592 Cassiopeiae
标准圆盘通常不足以对圆盘主导的激变变量（CV）进行建模，并产生比观察到的紫外光谱更蓝的光谱[Puebla et al 2007]。这些系统的X射线观测揭示了一个光学薄的边界层（BL），预计将出现在磁盘中的内孔。因此，我们截断了内盘。然而，而不是删除内部磁盘，我们施加的截断半径的无剪切边界条件，从而降低磁盘温度和产生的光谱，更好地适合紫外线数据。与我们修改后的磁盘，我们分析档案紫外光谱的三个novalikes，不能与标准磁盘。对于VY Scl系统MV Lyr和BZ Cam，我们将热膨胀的白矮星WD与冷修改的盘（$\dot{M} \sim $几个$10^{-9}M_{\odot}$ /年）安装在一起。对于V592 Cas，略微改变的圆盘（$\dot{M} \sim 6 \times 10^{-9}M_{\odot}$ /年）完全主导UV。这些结果与这些系统的Swift X射线观测结果一致[Balman et al 2014]，揭示了与ADAF样流动和/或热日冕合并的BL，其中能量的平流可能会引发外流并加热WD，从而解释了VY Scl系统中的高WD温度。这是进一步支持的事实，即X射线硬度比增加与浅的UV斜率在一个小的CV样品，我们检查。此外，对于105个盘主导的系统，国际紫外探测器（IUE）光谱UV斜率以与X射线通量与光学/UV通量的比率相同的顺序减小：从SU UMa的，到U Gem的，…
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…
