- ID:
- ivo://CDS.VizieR/J/A+A/524/A86
- Title:
- Light curves of SDSS J003941.06+005427.5
- Short Name:
- J/A+A/524/A86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present VLT spectroscopy and NTT photometry of the faint cataclysmic binary SDSS J003941.06+005427.5. This object shows triple-peaked H{alpha} emission with all three peaks variable in both strength and velocity. We measure an orbital period of 91.395+/-0.093min from the velocity variations of the wings of the Halpha emission line. Using the GALEX and SDSS photometry of this object, we determine a white dwarf temperature of 15000K and a very late (>=L2) spectral type for the companion star. These measurements, plus the relatively long orbital period, suggest that SDSS J003941.06+005427.5 may be a post-bounce cataclysmic variable. Doppler maps of the H{alpha} and HeI 6678{AA} emission features show an accretion disc with a non-uniform brightness and departures from Keplerian flow. The third emission peak is detected only in H{alpha} and at a relatively low velocity amplitude of 202+/-3km/s. We are unable to explain this emission as arising from either the white dwarf, the secondary star, or the accretion disc. We tentatively attribute this mysterious central peak to a coronal loop anchored at the secondary star. If confirmed, this would be the first example of a slingshot prominence in a CV with a low mass-transfer rate and/or a fully convective secondary star.
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- ID:
- ivo://CDS.VizieR/J/A+A/507/929
- Title:
- Light curves of SDSS J100658.40+233724.4
- Short Name:
- J/A+A/507/929
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present time-resolved spectroscopy and photometry of SDSS J100658.40+233724.4, which we have discovered to be an eclipsing cataclysmic variable with an orbital period of 0.18591324 days (267.71507min). The observed velocity amplitude of the secondary star is 276+/-7km/s, which an irradiation correction reduces to 258+/-12km/s. Doppler tomography of emission lines from the infrared calcium triplet supports this measurement. We have modelled the light curve using the LCURVE code and Markov Chain Monte Carlo simulations, finding a mass ratio of 0.51+/-0.08. From the velocity amplitude and the light curve analysis we find the mass of the white dwarf to be 0.78+/-0.12M_{sun}_ and the masses and radii of the secondary star to be 0.40+/-0.10M_{sun}_ and 0.466+/-0.036R_{sun}_, respectively. The secondary component is less dense than a normal main sequence star but its properties are in good agreement with the expected values for a CV of this orbital period. By modelling the spectral energy distribution of the system we find a distance of 676+/-40pc and estimate a white dwarf effective temperature of 16500+/-2000K.
- ID:
- ivo://CDS.VizieR/J/A+A/624/A133
- Title:
- LMC S154 (LHA 120-S 154) light curves
- Short Name:
- J/A+A/624/A133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Classical nova outburst has been suggested for a number of extragalactic symbiotic stars, but in none of the systems has it been proven. In this work we study the nature of one of these systems, LMC S154. We gathered archival photometric observations in order to determine the timescales and nature of variability in this system. Additionally we carried out photometric and spectroscopic monitoring of the system and fitted synthetic spectra to the observations. Carbon abundance in the photosphere of the red giant is significantly higher than that derived for the nebula, which confirms pollution of the circumbinary material by the ejecta from nova outburst. The photometric and spectroscopic data show that the system reached quiescence in 2009, which means that for the first time all of the phases of a nova outburst were observed in an extragalactic symbiotic star. The data indicate that most probably there were three outbursts observed in LMC S154, which would make this system a member of a rare class of symbiotic recurrent novae. The recurrent nature of the system is supported by the discovery of coronal lines in the spectra, which are observed only in symbiotic stars with massive white dwarfs and with short-recurrence-time outbursts. Gathered evidence is sufficient to classify LMC S154 as the first bona fide extragalactic symbiotic nova, which is likely a recurrent nova. It is also the first nova with a carbon-rich donor.
- ID:
- ivo://CDS.VizieR/J/AJ/153/144
- Title:
- Magnetic CVs spectra and other variable objects
- Short Name:
- J/AJ/153/144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The increasing number of synoptic surveys made by small robotic telescopes, such as the photometric Catalina Real-Time Transient Survey (CRTS), provides a unique opportunity to discover 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 that 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, 13 of which were 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 an 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.
- ID:
- ivo://CDS.VizieR/J/AJ/159/114
- Title:
- Magnetic CVs spectra & other variable objects II.
- Short Name:
- J/AJ/159/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second paper of a series presenting our search for magnetic cataclysmic variables (mCVs) among candidates selected mostly from the Catalina Real-Time Transient Survey. We present the identification spectra, obtained at the SOAR Telescope, as well as magnitudes and Gaia distances for 45 objects. Of these, 39 objects are identified as CVs, from which 8 targets show observational characteristics of mCVs, being 7 polars and 1 intermediate polar. The remaining 31 CVs in our sample are probably non-magnetic systems, in low (22 systems) or high (9 systems) accretion states. Six targets of the sample are not CVs (5 active galactic nuclei and 1 T-Tauri star). Among the 8 objects with mCV spectra, 6 are new classifications. Three polars were observed in low-accretion state, either revealing photospheric features of the secondary star and allowing the estimation of their spectral type, or presenting H{beta} Zeeman components associated to the white dwarf (WD) magnetic field. In addition to the results obtained in the first paper of the series, and depending on the confirmation of these classifications by observational follow-up, our results would increase the sample of known polars by about 9%.
- ID:
- ivo://CDS.VizieR/J/other/NewA/13.133
- Title:
- 2MASS photometry of cataclysmic variables
- Short Name:
- J/other/NewA/13.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spatial distribution, galactic model parameters and luminosity function of cataclysmic variables (CVs) in the solar neighbourhood have been found using distances estimated from the period-luminosity-colours (PLCs) relation of CVs. It can be concluded that exponential function fits better to the observational z-distributions of the whole CVs in the sample, non-magnetic CVs and dwarf novae, while the sech^2^ function is more appropriate for nova-like stars and polars. The vertical scaleheight of CVs is 158+/-14pc for the 2MASS J band limiting apparent magnitude of 15.8. The discrepancies between the theoretical and observational population studies of CVs can be at least partly removed if the sech^2^ density function is used in deriving the galactic model parameters. We estimated the vertical scaleheights of 128+/-20pc and 160+/-5pc for dwarf novae and nova-like stars, respectively. The local space density of CVs is found ~3x10^-5^pc^-3^ which is in agreement with the lower limit of the theoretical predictions. The luminosity function of CVs shows a trend toward higher space density at low luminosity, implying an increase in the number of short-period systems.
- ID:
- ivo://CDS.VizieR/J/AZh/75/231
- Title:
- MV Lyr - bursts and periods
- Short Name:
- J/AZh/75/231
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The analysis of photometric behavior of the nova-like star MV Lyr in B in the low brightness state in 1995-1996 based on the observations performed at the Crimean Astrophysical Observatory with the MTM-500 television system was presented.
- ID:
- ivo://CDS.VizieR/J/other/NewA/49.43
- Title:
- MWC 560 UBV(RI)c light curves
- Short Name:
- J/other/NewA/49.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- After 26 years from the major event of 1990, in early 2016 the puzzling symbiotic binary MWC 560 has gone into a new and even brighter outburst. We present our tight BVRCIC photometric monitoring of MWC 560 (451 independent runs distributed over 357 different nights), covering the 2005-2016 interval, and the current outburst in particular. A stricking feature of the 2016 outburst has been the suppression of the short term chaotic variability during the rise toward maximum brightness, and its dominance afterward with an amplitude in excess of 0.5mag. Similar to the 1990 event when the object remained around maximum brightness for ~6 months, at the time Solar conjunction prevented further observations of the current outburst, MWC 560 was still around maximum, three months past reaching it. We place our observations into a long term context by combining with literature data to provide a complete 1928-2016 lightcurve. Some strong periodicities are found to modulate the optical photometry of MWC 560. A period of 1860-days regulate the occurence of bright phases at BVRC bands (with exactly 5.0 cycles separating the 1990 and 2016 outbursts), while the peak brightness attained during bright phases seems to vary with a ~9570-days cycle. A clean 331-day periodicity modulate the Ic lightcurve, where the emission from the M giant dominates, with a lightcurve strongly reminiscent of an ellipsoidal distortion plus irradiation from the hot companion. Pros and cons of 1860 and 331 days as the system orbital period are reviewed, waiting for a spectroscopic radial velocity orbit of the M giant to settle the question (provided the orbit is not oriented face-on).
- ID:
- ivo://CDS.VizieR/J/MNRAS/402/436
- Title:
- New Dwarf novae in SDSS, GALEX and astrom. cat.
- Short Name:
- J/MNRAS/402/436
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By cross-matching blue objects from the Sloan Digital Sky Survey with Galaxy Evolution Explorer and the astrometric catalogues USNO-B1.0, GSC2.3 and CMC14, 64 new dwarf nova candidates with one or more observed outbursts have been identified. 14 of these systems are confirmed as cataclysmic variables through existing and follow-up spectroscopy. A study of the amplitude distribution and an estimate of the outburst frequency of these new dwarf novae and those discovered by the Catalina Real-time Transient Survey indicate that besides systems that are faint because they are farther away, there also exists a population of intrinsically faint dwarf novae with rare outbursts.
- ID:
- ivo://CDS.VizieR/J/PASP/109/441
- Title:
- Northern Cataclysmic Variables
- Short Name:
- J/PASP/109/441
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An average of 30 B,V secondary standards per field have been established for 76 variable stars. These are mostly cataclysmic variables of various subclasses but also include a variety of other kinds of variable stars. The standards are within a few arc minutes of the variable and are therefore well suited for CCD photometry. The standards have brightnesses of V~12-17 and have a typical accuracy per standard of +/-0.01mag. (c) Astronomical Society of the Pacific
