- ID:
- ivo://CDS.VizieR/J/MNRAS/505/1135
- Title:
- Gaia/IPHAS catalogue of Ha-excess sources
- Short Name:
- J/MNRAS/505/1135
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present a catalogue of point-like H{alpha}-excess sources in the Northern Galactic Plane. Our catalogue is created using a new technique that leverages astrometric and photometric information from Gaia to select H{alpha}-bright outliers in the INT Photometric H{alpha} Survey of the Northern Galactic Plane (IPHAS), across the colour-absolute magnitude diagram. To mitigate the selection biases due to stellar population mixing and to extinction, the investigated objects are first partitioned with respect to their positions in the Gaia colour-absolute magnitude space, and in the Galactic coordinates space, respectively. The selection is then performed on both partition types independently. Two significance parameters are assigned to each target, one for each partition type. These represent a quantitative degree of confidence that the given source is a reliable H{alpha}-excess candidate, with reference to the other objects in the corresponding partition. Our catalogue provides two flags for each source, both indicating the significance level of the H{alpha}-excess. By analysing their intensity in the H{alpha} narrow band, 28496 objects out of 7474835 are identified as H{alpha}-excess candidates with a significance higher than 3. The completeness fraction of the H{alpha} outliers selection is between 3% and 5%. The suggested 5sigma conservative cut yields a purity fraction of 81.9%.
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Search Results
- ID:
- ivo://CDS.VizieR/J/other/NewA/34.234
- Title:
- Galactic cataclysmic variables distances
- Short Name:
- J/other/NewA/34.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to determine the spatial distribution, Galactic model parameters and luminosity function of cataclysmic variables (CVs), a J-band magnitude limited sample of 263 CVs has been established using a newly constructed period-luminosity-colours (PLCs) relation which includes J,KsJ,Ks and W1W1-band magnitudes in 2MASS and WISE photometries, and the orbital periods of the systems. This CV sample is assumed to be homogeneous regarding to distances as the new PLCs relation is calibrated with new or re-measured trigonometric parallaxes.
- ID:
- ivo://CDS.VizieR/J/AJ/131/2673
- Title:
- H{alpha} radial velocities of AM Her
- Short Name:
- J/AJ/131/2673
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations in the red region of the spectrum of the magnetic cataclysmic variable prototype AM Her during its 2005 low state. We confirm the unexpected structure of the H{alpha} emission line and verify most of the conclusions of our earlier study: the line is typically triple-peaked, and the radial velocity curves of all three components are phased with the radial velocities of absorption features from the photosphere of the M dwarf secondary star.
- ID:
- ivo://CDS.VizieR/J/MNRAS/435/707
- Title:
- H{alpha} velocity curves of IM Eri
- Short Name:
- J/MNRAS/435/707
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report photometric detections of orbital and superorbital signals, and negative orbital sidebands, in the light curves of the nova-like cataclysmic variables AQ Mensae and IM Eridani. The frequencies of the orbital, superorbital and sideband signals are 7.0686 (3), 0.263 (3) and 7.332 (3) cycles/d (c/d) in AQ Mensae, and 6.870 (1), 0.354 (7) and 7.226 (1) c/d in IM Eridani. We also find a spectroscopic orbital frequency in IM Eridani of 6.86649 (2) c/d. These observations can be reproduced by invoking an accretion disc that is tilted with respect to the orbital plane. This model works well for X-ray binaries, in which irradiation by a primary neutron star can account for the disc's tilt. A likely tilt mechanism has yet to be identified in CVs, yet the growing collection of observational evidence indicates that the phenomenon of tilt is indeed at work in this class of object. The results presented in this paper bring the number of CVs known to display signals associated with retrograde disc precession to 12. We also find AQ Men to be an eclipsing system. The eclipse depths are highly variable, which suggests that the eclipses are grazing. This finding raises the possibility of probing variations in disc tilt by studying systematic variations in the eclipse profile.
- ID:
- ivo://CDS.VizieR/J/MNRAS/429/2143
- Title:
- Hidden population of AM CVns in the SDSS
- Short Name:
- J/MNRAS/429/2143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the latest results from a spectroscopic survey designed to uncover the hidden population of AM Canum Venaticorum (AM CVn) binaries in the photometric database of the Sloan Digital Sky Survey (SDSS). We selected ~2000 candidates based on their photometric colours, a relatively small sample which is expected to contain the majority of all AM CVn binaries in the SDSS (expected to be ~50). We present two new candidate AM CVn binaries discovered using this strategy: SDSS J104325.08+563258.1 and SDSS J173047.59+554518.5. We also present spectra of 29 new cataclysmic variables, 23 DQ white dwarfs and 21 DZ white dwarfs discovered in this survey. The survey is now approximately 70 per cent complete, and the discovery of seven new AM CVn binaries indicates a lower space density than previously predicted. From the essentially complete g~19 sample, we derive an observed space density of (5+/-3)*10^-7^pc^-3^; this is lower than previous estimates by a factor of 3. The sample has been cross-matched with the GALEX All-Sky Imaging Survey database, and with Data Release 9 of the UKIRT (United Kingdom Infrared Telescope) Infrared Deep Sky Survey (UKIDSS). The addition of UV photometry allows new colour cuts to be applied, reducing the size of our sample to ~1100 objects. Optimising our followup should allow us to uncover the remaining AM CVn binaries present in the SDSS, providing the larger homogeneous sample required to more reliably estimate their space density.
- ID:
- ivo://CDS.VizieR/J/AJ/156/150
- Title:
- High-time-resolution photometry of AR Scorpii
- Short Name:
- J/AJ/156/150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The unique binary AR Scorpii consists of an asynchronously rotating, magnetized white dwarf (WD) that interacts with its red-dwarf companion to produce a large-amplitude, highly coherent pulsation every 1.97 minutes. Over the course of two years, we obtained 39 hours of time-resolved, optical photometry of AR Sco at a typical cadence of 5 s to study this pulsation. We find that it undergoes significant changes across the binary orbital period and that its amplitude, phase, and waveform all vary as a function of orbital phase. We show that these variations can be explained by constructive and destructive interference between two periodic, double-peaked signals: the spin-orbit beat pulse, and a weaker WD spin pulse. Modeling of the light curve indicates that in the optical, the amplitude of the primary spin pulse is 50% of the primary beat amplitude, while the secondary maxima of the beat and spin pulses have similar amplitudes. Finally, we use our timings of the beat pulses to confirm the presence of the disputed spin-down of the WD. We measure a beat-frequency derivative of {nu}=(-5.14+/-0.32)x10^-17^ Hz/s and show that this is attributable to the spin-down of the WD. This value is approximately twice as large as the estimate from Marsh et al. but is nevertheless consistent with the constraints established in Potter & Buckley (2018MNRAS.478L..78P). Our precise measurement of the spin-down rate confirms that the decaying rotational energy of the magnetized WD is sufficient to power the excess electromagnetic radiation emitted by the binary.
- ID:
- ivo://CDS.VizieR/J/A+A/608/A36
- Title:
- IGR J19552+0044 BV light curves and spectra
- Short Name:
- J/A+A/608/A36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on XMM-Newton X-ray observations IGR J19552+0044 appears to be either a pre-polar or an asynchronous polar. Aims. We conducted follow-up optical observations to identify the sources and periods of variability precisely and to classify this X-ray source correctly. Extensive multicolor photometric and medium- to high-resolution spectroscopy observations were performed and period search codes were applied to sort out the complex variability of the object. We found firm evidence of discording spectroscopic (81.29+/-0.01m) and photometric (83.599+/-0.002m) periods that we ascribe to the white dwarf (WD) spin period and binary orbital period, respectively. This confirms that IGR J19552+0044 is an asynchronous polar. Wavelength dependent variability and its continuously changing shape point at a cyclotron emission from a magnetic WD with a relatively low magnetic field below 20MG. The difference between the WD spin period and the binary orbital period proves that IGR J19552+0044 is a polar with the largest known degree of asynchronism (0.97 or 3%).
- ID:
- ivo://CDS.VizieR/J/A+A/480/409
- Title:
- IPHAS symbiotic stars candidates
- Short Name:
- J/A+A/480/409
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The study of symbiotic stars is essential to understand important aspects of stellar evolution in interacting binaries. Their observed population in the Galaxy is however poorly known, and is one to three orders of magnitudes smaller than the predicted population size. IPHAS, the Isaac Newton Telescope Photometric H{alpha} survey of the Northern Galactic plane, gives us the opportunity to make a systematic, complete search for symbiotic stars in a magnitude-limited volume, and discover a significant number of new systems. A method of selecting candidate symbiotic stars by combining IPHAS and near-IR (2MASS) colours is presented. It allows us to distinguish symbiotic binaries from normal stars and most of the other types of H{alpha} emission line stars in the Galaxy. The only exception are T Tauri stars, which can however be recognized because of their concentration in star forming regions.
- ID:
- ivo://CDS.VizieR/J/AJ/147/105
- Title:
- Light curve of HR Lyr over 1991-2012
- Short Name:
- J/AJ/147/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 22 yr light curve of HR Lyr, acquired with a typical cadence of 2-6 days, is examined for periodic and quasi-periodic variations. No persistent periodicities are revealed. Rather, the light curve variations often take the form of nearly linear rises and falls having typical e-folding times of about 100 days. Occasional ~0.6mag outbursts are also seen, with properties similar to those of small outbursts found in some nova-like cataclysmic variables. When the photometry is formed into yearly averages, a decline of 0.012+/-0.005mag/yr is apparent, consistent with the fading of irradiation-induced Mdot following the nova. The equivalent width of H{alpha} is tabulated at three epochs over the interval 1986-2008 in order to compare with a recent result for DK Lac in which H{alpha} was found to be fading 50 yr after the nova. However, our results for such a fading in HR Lyr are inconclusive.
- ID:
- ivo://CDS.VizieR/J/AJ/147/10
- Title:
- Light curve of V794 Aql over 1990-2012
- Short Name:
- J/AJ/147/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 1990-2012 light curve of the nova-like (NL) cataclysmic variable V794 Aql is studied in order to characterize and better understand the transitions to and from the faint state, and the variations within the bright state. Investigations of earlier portions of this data had concluded that the transitions to the low state were much slower than the rapid recovery, giving a sawtoothed appearance to the light curve. This behavior differs from that of most other VY Scl stars, which led to an interpretation of the large amplitude sawtooths as being due to an accretion disk (AD) instability. However, more recent photometry strongly suggests that the bright state itself has transitions of 1-1.5mag, and that earlier studies had intermixed these bright state variations with the transitions to the low state. These newly recognized variations within the bright state sometimes appear as small outbursts (OBs) with typical amplitudes of 0.5-1.5mag and spacings of ~15-50days. The rise times of the OBs are 2-3 times faster than the decline times. We argue that the V794 Aql bright state variations are due to AD behavior similar to that seen in dwarf novae, but with varying degrees of stability. Similar regular small OBs have also been reported in other NL CVs, which we compare with V794 Aql. The true deep low states in V794 Aql appear to be normal, having transition speeds and shapes very similar to the transitions in other VY Scl stars.
