Statistical properties of dwarf novae-type cataclysmic variables: the outburst catalogue

Coppejans, D. L.; Körding, Elmar; Knigge, Christian; Pretorius, Magaretha L.; Woudt, P. A.; Groot, P.; Eck, Cameron L. Van; Drake, A. J.

doi:10.1093/mnras/stv2921

Cited by 46 publications

(50 citation statements)

References 53 publications

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“…Duty cycles can also be obtained as the ratio of the number of outburst detections to the total number of observations, for which we find consistent results with duty cycle values of 0.08, 0.22, 0.04, and 0.07 for SW1-4, respectively. These values are consistent with typical DNe: for instance, Coppejans et al (2016) found DN duty cycles ranging from 0.01-0.36, using light curves spanning 8 to 9 years of several hundred events from the Catalina Real-Time Transient Survey.…”

Section: Discussionsupporting

confidence: 80%

Near-ultraviolet detections of four dwarf nova candidates in the globular cluster 47 Tucanae

Modiano

Parikh

Wijnands

2020

A&A

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We investigate near-ultraviolet (NUV) variability in the Galactic globular cluster (GC) 47 Tucanae (47 Tuc). This work was undertaken within the GC sub-project of the Transient UV Objects project, a programme which aims to find and study transient and strongly variable UV sources. Globular clusters are ideal targets for transient searches because of their high stellar densities and large populations of variable systems. Using all 75 archival observations of 47 Tuc obtained with the UV/optical telescope (UVOT) aboard the Neil Gehrels Swift observatory with the uvm2 filter, we searched for UV variability using a specialised pipeline which utilises difference image analysis. We found four clear transients, hereafter SW1-4, with positions consistent with those of known cataclysmic variables (CVs) or CV candidates identified previously using Hubble Space Telescope observations. All four sources exhibit significant outbursts, likely brightening by several orders of magnitude. Based on the inferred outburst properties and the association with known CVs, we tentatively identify the UV transients as CV-dwarf novae (DNe). Two DNe have been previously observed in 47 Tuc: V2, which has a position consistent with that of SW4; and AKO 9, which was not in outburst during any of the UVOT observations. We thus increase the known number of DNe in 47 Tuc to 5 and the total number of detected DNe in all Galactic GCs combined from 14 to 17. We discuss our results in the context of the apparent scarcity of DNe in GCs. We suggest that the likely cause is observational biases, such as limited sensitivity due to the high background from unresolved stars in the GC and limited angular resolution of the telescopes used. We additionally detected one strongly variable source in 47 Tuc, which could be identified as the known RR Lyrae star HV 810. We found its period to have significantly increased with respect to that measured from data taken in 1988.

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Section: Discussionsupporting

confidence: 80%

Near-ultraviolet detections of four dwarf nova candidates in the globular cluster 47 Tucanae

Modiano

Parikh

Wijnands

2020

A&A

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“…For both two groups with specific features of CVs, some known CV spectra are needed as templates to pick up the candidates in the initial dataset. We first collect the CVs catalogues from the literatures as well as the SIMBAD database, which eventually contain 4,215 CVs without being removed duplicate sources (Downes & Shara 1993;Wenger et al 2000;Downes et al 2001;Szkody et al 2011;Coppejans et al 2014;Drake et al 2014;Breedt et al 2014;Coppejans et al 2016). Cross-matching known CVs and LAMOST catalogs within a cross radius of 5 , about 500 LAMOST spectra of known CVs are obtained.…”

Section: Methodsmentioning

confidence: 99%

Spectroscopically Identified Cataclysmic Variables from the LAMOST Survey. I. The Sample

Hou

Luo

et al. 2020

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A sample of Cataclysmic Variables (CVs) is presented including spectroscopically identified 380 spectra of 245 objects, of which 58 CV candidates are new discoveries. The BaggingTopPush and the Random Forest algorithms are applied to the Fifth Data Release (DR5) of LAMOST to retrieve CVs with strong emission lines and with broad absorption lines respectively. Based on spectroscopic classification, 134 dwarf novae, 41 nova-like variables and 19 magnetic CVs are identified from the sample. In addition, 89 high-inclination systems and 33 CVs showing companion stars are recognized and discussed for their distinct spectral characteristics. Comparisons between CVs from LAMOST and from published catalogs are made in spatial and magnitude distribution, and the difference of their locus in Gaia color-absolute magnitude diagram (CaMD) are also investigated. More interestingly, for two dwarf novae observed through LAMOST and SDSS in different epoch, their spectra both in quiescence phase and during outburst are exhibited.

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“…The spectrum flux corresponds to approximately 19.3 mag in the V band, consistent with the quiescent flux level. Coppejans et al (2016) classify it as a dwarf nova with 3 detected outbursts. Its spectrum resembles the spectrum of the IP candidate CTCV2056-30 (see section 6.2.11) and short-period IPs like SDSS J2333 (Southworth et al 2007;Szkody et al 2005) and HT Cam (Kemp et al 2002), so we suggest that it is a member of this class.…”

Section: Css1012-18 (Css120324:101217-182411 = Sss110203:101217-182411)mentioning

confidence: 99%

“…CRTS combines three distinct surveys -the Mount Lemmon Survey (MLS) and the Catalina Schmidt Survey (CSS) in the Northern Hemisphere and the Siding Spring Survey (SSS) in the South -covering an area of 30,000 deg 2 with a typical cadence of two weeks, reaching a depth of 19-21 magnitudes. The CRTS has already found thousands of CV candidates, which are rapidly announced via their website 1 and are subject to follow-up investigations (e.g., Coppejans et al 2014;Drake et al 2014;Breedt et al 2014; Thorstensen & Skinner 2012;Coppejans et al 2016). As the prime criterion for the CRTS detecting transients is the brightening by 2 or more magnitudes, it turns out to be very effective in discovering non-magnetic CVs, as the follow-up works mentioned above have shown.…”

Section: Introductionmentioning

confidence: 99%

Exploratory Spectroscopy of Magnetic Cataclysmic Variables Candidates and Other Variable Objects

Oliveira¹,

Rodrigues²,

Cieslinski³

et al. 2017

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The increasing number of synoptic surveys made by small robotic telescopes, such as the photometric Catalina Real-Time Transient Survey (CRTS), represents a unique opportunity for the discovery of variable sources and improves the statistical samples of such classes of objects. Our goal is the discovery of magnetic Cataclysmic Variables (mCVs). These are rare objects, which probe interesting accretion scenarios controlled by the white dwarf magnetic field. In particular, improved statistics of mCVs would help to address open questions on their formation and evolution. We performed an optical spectroscopy survey to search for signatures of magnetic accretion in 45 variable objects selected mostly from the CRTS. In this sample we found 32 CVs, 22 being mCV candidates from which 13 are previously unreported as such. If the proposed classifications are confirmed, it would represent an increase of 4% in the number of known polars and 12% in the number of known IPs. A fraction of our initial sample was classified as extragalactic sources or other types of variable stars by the inspection of the identification spectra. Despite the inherent complexity in identifying a source as a mCV, variability-based selection followed by spectroscopic snapshot observations has proved to be an efficient strategy for their discoveries, being a relatively inexpensive approach in terms of telescope time.

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Statistical properties of dwarf novae-type cataclysmic variables: the outburst catalogue

Cited by 46 publications

References 53 publications

Near-ultraviolet detections of four dwarf nova candidates in the globular cluster 47 Tucanae

Near-ultraviolet detections of four dwarf nova candidates in the globular cluster 47 Tucanae

Spectroscopically Identified Cataclysmic Variables from the LAMOST Survey. I. The Sample

Exploratory Spectroscopy of Magnetic Cataclysmic Variables Candidates and Other Variable Objects

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