- ID:
- ivo://CDS.VizieR/J/A+A/600/A96
- Title:
- V407 Cyg spectral variations
- Short Name:
- J/A+A/600/A96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The outburst of the symbiotic recurrent nova V407 Cyg in 2010 has been studied by numerous authors. On the other hand, its spectral variations in the quiescent stage have not been well studied yet. This paper is probably the first report for the relation between the pulsation of the secondary Mira variable and the temperature of the primary hot component for V407 Cyg. The spectral variation in the post-outburst stage has been monitored to study the properties of this object. In the course of this work, we found some unexpected spectral variations around the light maximum of the secondary Mira variable in 2012. The relation between the mass transfer in the binary system and the pulsation of the secondary Mira variable is studied. High- and low-resolution optical spectra obtained at the Astronomical Observatories at Asiago were used. The photometric data depend on the database of the VSNET.
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- ID:
- ivo://CDS.VizieR/J/AJ/146/107
- Title:
- Velocity curves of 10 cataclysmic binaries
- Short Name:
- J/AJ/146/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on ground-based optical observations of 10 cataclysmic binaries that were discovered through their X-ray emission. Time-resolved radial velocity spectroscopy yields unambiguous orbital periods for eight objects and ambiguous results for the remaining two. The orbital periods range from 87 minutes to 9.38 hr. We also obtained time-series optical photometry for six targets, four of which have coherent pulsations. These periods are 1218s for 1RXSJ045707.4+452751, 628s for AXJ1740.2-2903, 477s for AXJ1853.3-0128, and 935s for IGRJ19267+1325. A total of seven of the sources have coherent oscillations in X-rays or optical, indicating that they are intermediate polars (DQ Herculis stars). Time-resolved spectroscopy of one object, SwiftJ2218.4+1925, shows that it is an AM Herculis star, or polar, and IGRJ19552+0044 may also be in that class. For another object, SwiftJ0746.2-1611, we find an orbital period of 9.384 hr and detect the spectrum of the secondary star. The secondary's spectral contribution implies a distance of 900 (+190, -150)pc, where the error bars are estimated using a Monte Carlo technique to account for correlated uncertainties.
- ID:
- ivo://CDS.VizieR/J/A+A/540/A15
- Title:
- V795 Her differential photometry
- Short Name:
- J/A+A/540/A15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V-band CCD observations of the cataclysmic variable V795 Her obtained between 2008 and 2010. The observing run on a given night consisted of a dense series of V-band images (exposure time of 20 seconds). Heliocentric Julian Date of each CCD image is given for the center of the exposure. A typical standard deviation of a single measurement of the magnitude of V795 Her on a given CCD frame was about 0.01 mag. GSC 02595-00575 (GSC2.3 N3JJ000148) was used as the comparison star (abbreviated as C) while GSC 02595-00718 served as the check star (abbreviated as C1).
- ID:
- ivo://CDS.VizieR/J/AJ/141/121
- Title:
- V446 Her V light curves
- Short Name:
- J/AJ/141/121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V446 Her is the best example of an old nova which has developed dwarf nova (DN) eruptions in the post-nova state. We report on observed properties of the long-term light curve of V446 Her, using photometry over 19 years.
- ID:
- ivo://CDS.VizieR/J/A+A/553/A28
- Title:
- VI light curves and spectra of V479 And
- Short Name:
- J/A+A/553/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We conducted a multi-wavelength study to unveil the properties of the extremely long-period cataclysmic variable V479 And. We performed series of observations, including moderate to high spectral resolution optical spectrophotometry, X-ray observations with Swift, linear polarimetry and near-IR photometry. This binary system is a low-inclination ~17{deg} system with a 0.594093(4) day orbital period. The absorption line complex in the spectra indicate a G8-K0 spectral type for the donor star, which has departed from the zero-age main sequence. This implies a distance to the object of about 4kpc. The primary is probably a massive 1.1-1.4M_{sun}_ magnetic white dwarf, accreting matter at a rate dM/dt>10^-10^M_{sun}_/yr. This rate can be achieved if the donor star fills its corresponding Roche lobe, but there is little observational evidence for a mass-transfer stream in this system. An alternative explanation is a stellar wind from the donor star, although such a high rate mass loss is not anticipated from a subgiant. If the strongly magnetic white dwarf in V479 And is confirmed by future observations, the system the polar with the longest observed orbital period. We also discuss the evolutionary state of V479 And.
- ID:
- ivo://CDS.VizieR/J/A+A/638/A130
- Title:
- VLBI images of gamma-ray nova V407 Cygni
- Short Name:
- J/A+A/638/A130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In 2010 March, the Large Area Telescope on board Fermi revealed a transient gamma-ray source that is positionally coincident with the optical nova in the symbiotic binary, V407 Cyg. This event marked the first discovery of gamma-ray emission from a nova. We aim to obtain resolved radio imaging of the material involved in the nova event, to determine the ejecta geometry and advance velocity directly in the image plane, and to constrain the physical conditions of the system. We observed the source with the European VLBI (Very Long Baseline Interferometry) Network in real time mode, at 1.6 and 5GHz, and the Very Long Baseline Array at 1.6, 5, and 8.4GHz. In total, we observed the source over 16 epochs, starting 20 days after the optical discovery and continuing for over six months. Milliarcsecond-scale radio emission is detected in 10/16 epochs of observations. The source is initially very dim but it later shows a substantial increase in brightness and a resolved shell-like structure 40-90 days after the optical event. The shell has a projected elliptical shape and is asymmetric in brightness and spectral index, being brighter and characterised by a rising spectrum at the south-eastern edge. We determine a projected expansion velocity of ~3500km/s in the initial phase (for an adopted 2.7kpc distance), and ~2100km/s between day 20 and 91. We also found an emitting feature about 350 mas (940AU) to the north-west, advancing at a projected velocity of ~700km/s along the polar axis of the binary. The total flux density in the VLBI images is significantly lower than that previously reported at similar epochs and over much wider angular scales with the VLA. Optical spectra convincingly demonstrated that in 2010 we were viewing V407 Cyg along the equatorial plane and from behind the Mira. Our radio observations image the bipolar flow of the ejecta perpendicular to the orbital plane, where deceleration is much lower than through the equatorial plane probed by the truncated profile of optical emission lines. The separated polar knot at 350 mas and the bipolar flow strictly resemble a similar arrangement seen in Hen 2-104, another symbiotic Mira seen equator-on that went through a large outburst ~5700yrs ago. The observed ~700km/s expansion constrains the launch date of the polar knot around 2004, during the accretion-fed active phase preceding the 2010 nova outburst.
- ID:
- ivo://CDS.VizieR/J/AJ/145/45
- Title:
- V light curve of BZ Camelopardalis
- Short Name:
- J/AJ/145/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Sequences of spectra of the nova-like cataclysmic variable (CV) BZ Cam were acquired on nine nights in 2005-2006 in order to study the time development of episodes of wind activity known to occur frequently in this star. We confirm the results of Ringwald & Naylor that the P-Cygni absorption components of the lines mostly evolve from higher expansion velocity to lower velocity as an episode progresses. We also commonly find blueshifted emission components in the H{alpha} line profile, whose velocities and durations strongly suggest that they are also due to the wind. Curiously, Ringwald & Naylor reported common occurrences of redshifted H{alpha} emission components in their BZ Cam spectra. We have attributed these emission components in H{alpha} to occasions when gas concentrations in the bipolar wind (both front side and back side) become manifested as emission lines as they move beyond the disk's outer edge. We also suggest, based on changes in the P-Cygni profiles during an episode, that the progression from larger to smaller expansion velocities is due to the higher velocity portions of a wind concentration moving beyond the edge of the continuum light of the disk first, leaving a net redward shift of the remaining absorption profile. We derive a new orbital ephemeris for BZ Cam, using the radial velocity of the core of the HeI{lambda}5876 line, finding P=0.15353(4). Using this period, the wind episodes in BZ Cam are found to be concentrated near the inferior conjunction of the emission line source. This result helps confirm that the winds in nova-like CVs are often phase dependent, in spite of the puzzling implication that such winds lack axisymmetry. We argue that the radiation-driven wind in BZ Cam receives an initial boost by acting on gas that has been lifted above the disk by the interaction of the accretion stream with the disk, thereby imposing flickering timescales onto the wind events, as well as leading to an orbital modulation of the wind due to the non-axisymmetric nature of the stream/disk interaction. Simultaneous photometry and spectroscopy were acquired on three nights in order to test the possible connection between flickering continuum light and the strength of the front-side wind. We found strong agreement on one night, some agreement on another, and no agreement on the third. We suggest that some flickering events lead to only back-side winds which will not have associated P-Cygni profiles.
- ID:
- ivo://CDS.VizieR/J/A+A/486/505
- Title:
- V light curve of SDSS J080434.20+510349.2
- Short Name:
- J/A+A/486/505
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed a new cataclysmic variable (CV) SDSS J080434.20+510349.2 to study the origin of long-term variability found in its light curve. Multi-longitude, time-resolved, photometric observations were acquired to analyze this uncommon behavior, which has been found in two newly discovered CVs. This study of SDSS J080434.20+510349.2 concerns primarily the understanding of the nature of the observed, double-humped, light curve and its relation to a cyclic brightening that occurs during quiescence. The observations were obtained early in 2007, when the object was at about V~17.1, about 0.4mag brighter than the pre-outburst magnitude. The light curve shows a sinusoidal variability with an amplitude of about 0.07mag and a periodicity of 42.48min, which is half of the orbital period of the system. We observed in addition two "mini-outbursts" of the system of up to 0.6mag, which have a duration of about 4days each. The "mini-outburst" has a symmetric profile and is repeated in approximately every 32days. Subsequent monitoring of the system shows a cyclical behavior of such "mini-outbursts" with a similar recurrence period. The origin of the double-humped light curve and the periodic brightening is discussed in the light of the evolutionary state of SDSS J080434.20+510349.2.
- ID:
- ivo://CDS.VizieR/J/A+A/497/437
- Title:
- V light curves of DI UMa
- Short Name:
- J/A+A/497/437
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report an analysis of photometric behaviour of DI UMa, an extremely active dwarf nova. The observational campaign (completed in 2007) covers five superoutbursts and four normal outbursts. We examined principal parameters of the system to understand peculiarities of DI UMa, and other active cataclysmic variables. Based on precise photometric measurements, temporal light curve behaviour, O-C analysis, and power spectrum analysis, we investigated physical parameters of the system. We found that the period of the supercycle now equals 31.45+/-0.3days. Observations during superoutbursts infer that the period of superhumps equals P_sh_=0.055318(11)days (79.66+/-0.02min). During quiescence, the light curve reveals a modulation of period P_orb_=0.054579(6)days (78.59+/-0.01min), which we interpret as the orbital period of the binary system. The values obtained allowed us to determine a fractional period excess of 1.35+/-0.02%, which is surprisingly small compared to the usual value for dwarf novae (2%-5%). A detailed O-C analysis was performed for two superoutbursts with the most comprehensive coverage. In both cases, we detected an increase in the superhump period with a mean rate of (dP/dt)/P_sh_=4.4(1.0)x10^-5^. Based on these measurements, we confirm that DI UMa is probably a period bouncer, an old system that reached its period minimum a long time ago, has a secondary that became a degenerate brown dwarf, the entire system evolving now toward longer periods. DI UMa is an extremely interesting object because we know only one more active ER UMa star with similar characteristics (IX Dra).
- ID:
- ivo://CDS.VizieR/J/A+A/639/L10
- Title:
- VRI photometry of V392 Per
- Short Name:
- J/A+A/639/L10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Nova Per 2018 (= V392 Per) halted the decline from maximum when it was 2mag brighter than quiescence and since 2019 has been stable at such a plateau. The ejecta have already fully diluted into the interstellar space. We obtained BVRIgrizY photometry and optical spectroscopy of V392 Per during the plateau phase and compared it with equivalent data gathered prior to the nova outburst. We find the companion star (CS) to be a G9 IV/III and the orbital period to be 3.4118 days, making V392 Per the longest known period for a classical nova. The location of V392 Per on the theoretical isochrones is intermediate between that of classical novae and novae erupting within symbiotic binaries, in a sense bridging the gap. The reddening is derived to be E(B-V)=0.72 and the fitting to isochrones returns a 3.6Gyr age for the system and 1.35M_{sun}_, 5.3R_{sun}_, and 15L_{sun}_ for the companion. The huge Ne overabundance in the ejecta and the very fast decline from nova maximum both point to a massive white dwarf (M(WD)>=1.1/1.2M_{sun}_). The system is viewed close to pole-on conditions and the current plateau phase is caused by irradiation of the CS by the WD still burning at the surface.
