V709 Cas Research Articles

Timing Analysis of the Intermediate Polar V709 Cas

We have carried detailed time-resolved timing analysis of an intermediate polar V709 Cas, using the long-baseline, short-cadence optical photometric data from the Transiting Exoplanet Survey Satellite. We found an orbital period of 5.3341±0.0004 hr, a spin period of 312.75±0.02 sec, and a beat period of 317.93±0.03 sec, which is similar to the earlier published results. From the continuous high cadence data, we found that V709 Cas is a disc overflow system with disc-fed dominance.

Characterizing the Advective Hot Flows of Nova-like Cataclysmic Variables in the X-Rays: The Case of BZ Cam and V592 Cas

We present a joint spectral analysis of ROSAT PSPC, Swift X-ray Telescope, and Nuclear Spectroscopic Telescope Array Focal Plane Module A/B (FPMA/B) data of the nova-like (NL) cataclysmic variables (CVs) BZ Cam and V592 Cas in the 0.1–78.0 keV band. Plasma models of collisional equilibrium fail to model the 6.0–7.0 iron line complex and continuum with larger than 2.0. Our results show nonequilibrium ionization (NEI) conditions in the X-ray plasma with temperatures of 8.2–9.4 keV and 10.0–12.9 keV for BZ Cam and V592 Cas, respectively. The centroids of He-like and H-like iron ionization lines are not at their equilibrium values as expected from NEI conditions. We find power-law spectral components that reveal the existence of scattering and Comptonization with a photon index of 1.50–1.87. We detect a P Cygni profile in the H-like iron line of BZ Cam translating to outflows of 4500–8700 km s−1 consistent with the fast winds in the optical and UV. This is the first time such a fast collimated outflow is detected in the X-rays from an accreting CV. An iron Kα line around 6.2–6.5 keV is found revealing the existence of reflection effects in both sources. We study the broadband noise and find that the optically thick disk truncates in BZ Cam and V592 Cas consistent with transition to an advective hot flow structure. V592 Cas also exhibits a quasiperiodic oscillation at mHz. In general, we find that the two NLs portray spectral and noise characteristics as expected from advective hot accretion flows at low radiative efficiency.

Period Change and Third Body Analysis of a Binary Star V523 Cassiopeiae

V523 Cassiopeiae (V523 Cas) is a W UMa type of the eclipsing binary system which its orbital period is 0.23369 days. This study using a 0.5-meter telescope with CCD photometric system in V and R filters was conducted at the Regional Observatory for the Public, Chachoengsao, Thailand during 20 – 21 December 2018, UT. The obtained data were calculated using photometry method to construct the light curve of each wavelength bands and to determine the time of minimum. Consequently this study obtained the time of minimum of V523 Cas that HJD2458472.996 and HJD2458473.111, respectively. These values were used to compute the O-C curve and period change. The results show that the period of the V523 Cas is increasing which the rate of 5.59 × 10−3 second/year. Furthermore, the V523 Cas might be the third body in its system which far from the center of mass about 6.04 AU the orbital period is 91.3 years.

Measuring the masses of intermediate polars with NuSTAR: V709 Cas, NY Lup, and V1223 Sgr

The X-ray spectra of intermediate polars can be modelled to give a direct measurement of white dwarf mass. Here we fit accretion column models to NuSTAR spectra of three intermediate polars; V709 Cas, NY Lup and V1223 Sgr in order to determine their masses. From fits to 3-78 keV spectra, we find masses of $M_{\rm WD}=0.88^{+0.05}_{-0.04}M_{\odot}$, $1.16^{+0.04}_{-0.02}M_{\odot}$ and $0.75\pm0.02M_{\odot}$ for V709 Cas, NY Lup and V1223 Sgr, respectively. Our measurements are generally in agreement with those determined by previous surveys of intermediate polars, but with typically a factor $\sim2$ smaller uncertainties. This work paves the way for an approved NuSTAR Legacy Survey of white dwarf masses in intermediate polars.

A SOLAR-TYPE STELLAR COMPANION TO A DEEP CONTACT BINARY IN A QUADRUPLE SYSTEM

ABSTRACT The four-color (B, V, R c , I c ) light curves of V776 Cas are presented and analyzed using the Wilson–Devinney method. It is discovered that V776 Cas is an early F-type (F2V) overcontact binary with a very high contact degree (f = 64.6%) and an extremely low-mass ratio (q = 0.130), which indicate that it is at the final evolutionary stage of cool short-period binaries. The mass of the primary and secondary stars are calculated to be M 1 = 1.55(±0.04) M ⊙, M 2 = 0.20(±0.01) M ⊙. V776 Cas is supposed to be formed from an initially detached binary system via the loss of angular momentum due to the magnetic wind. The initial masses of the present primary and secondary components are calculated to be M 1i = 0.86(±0.10) M ⊙ and M 2i = 2.13(±0.04) M ⊙. The observed–calculated curve exhibits a cyclic period variation, which is due to the light-travel time effect caused by the presence of a third component with a period of 23.7 years. The mass of the third component is estimated to be M 3 = 1.04(±0.03) M ⊙ and the orbital inclination of the third component is calculated to be i′ = 33.°1. The distance of the binary system to the mass center of the triple system is calculated to be a 12 ′ ?> = 3.45 AU. The presence of the close-in tertiary component may play an important role in the formation and evolution of this binary system by drawing angular momentum from the central system.

UNAMBIGUOUS DETECTION OF REFLECTION IN MAGNETIC CATACLYSMIC VARIABLES: JOINT NuSTAR – XMM-NEWTON OBSERVATIONS OF THREE INTERMEDIATE POLARS

In magnetic cataclysmic variables (CVs), X-ray emission regions are located close to the white dwarf surface, which is expected to reflect a significant fraction of intrinsic X-rays above 10 keV, producing a Compton reflection hump. However, up to now, a secure detection of this effect in magnetic CVs has largely proved elusive because of the limited sensitivity of non-imaging X-ray detectors. Here we report our analysis of joint NuSTAR/XMM-Newton observations of three magnetic CVs, V709 Cas, NY Lup, and V1223 Sgr. The improved hard X-ray sensitivity of the imaging NuSTAR data has resulted in the first robust detection of Compton hump in all three objects, with amplitudes of ~1 or greater in NY Lup, and likely <1.0 in the other two. We also confirm earlier report of a strong spin modulation above 10 keV in V709 Cas, and report the first detection of small spin amplitudes in the others. We interpret this as due to different height of the X-ray emitting region among these objects. A height of ~0.2 white dwarf radii provides a plausible explanation for the low reflection amplitude of V709 Cas. Since emission regions above both poles are visible at certain spin phases, this can also explain the strong hard X-ray spin modulation. A shock height of ~0.05 white dwarf radii can explain our results on V1223 Sgr, while the shock height in NY Lup appears negligible.

SWIFTX-RAY TELESCOPE OBSERVATIONS OF THE NOVA-LIKE CATACLYSMIC VARIABLES MV Lyr, BZ Cam, AND V592 Cas

We present a total of ~ 45 ksec (3$\times$15 ksec) of SWIFT XRT observations for three non-magnetic nova-like (NL) Cataclysmic Variables (CVs) (MV Lyr, BZ Cam, V592 Cas) in order to study characteristics of Boundary Layers (BL) in CVs. The nonmagnetic NLs are found mostly in a state of high mass accretion rate ($\ge$1$\times$10$^{-9}$ Msun yr$^{-1}$) and some show occasional low states. Using the XRT data, we find optically thin multiple-temperature cooling flow type emission spectra with X-ray temperatures (kT$_{max}$) of 21-50 keV. These hard X-ray emitting boundary layers diverge from simple isobaric cooling flows indicating X-ray temperatures that are of virial values in the disk. In addition, we detect power law emission components from MV Lyr and BZ Cam and plausibly from V592 Cas which may be a result of the Compton scattering of the optically thin emission from the fast wind outflows in these systems and/or Compton up-scattering of the soft disk photons. The X-ray luminosities of the (multi-temperature) thermal plasma emission in the 0.1-50.0 keV range are (0.9-5.0)$\times$10$^{32}$ erg/sec. The ratio of the X-ray and disk luminosities (calculated from the UV-optical wavelengths) yield an efficiency (L$_{x}$/L$_{disk}$) ~ 0.01-0.001. Given this non-radiative ratio for the X-ray emitting boundary layers with no significant optically thick blackbody emission in the soft X-rays (consistent with ROSAT observations) together with the high/virial X-ray temperatures, we suggest that high state NL systems may have optically thin BLs merged with ADAF-like flows and/or X-ray coronae. In addition, we note that the axisymmetric bipolar and/or rotation dominated fast wind outflows detected in these three NLs (particularly BZ Cam and V592 Cas) or some other NL may also be explained in the context of ADAF-like BL regions.

The new period of the intermediate polar V709 Cas

AbstractWe present the results of 10 years of photometric CCD observations of the intermediate polar V709 Cas obtained by using different instruments during 2003–2013. We detected a new variability with a period of Pnew = 0.d016449979(5) which seems to be real. The spin variability is not clearly seen in all our data, so we are unable to study any evolution of the white dwarf rotation. From the best night (in 2010) we obtained a spin period of Pspin = 311.s8(5). We analyzed the orbital variability using (O – C) analysis. We found no variations of the orbital period on a timescale of 10 years, but the linear fit to the (O – C) diagram shows that the value of the orbital period is Porb = 0.d2222123(6), which is close to the earlier published values. (© 2014 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

NEW ORBITAL PARAMETERS AND RADIAL VELOCITY CURVE ANALYSIS OF SPECTROSCOPIC BINARY STARS

We use a Probabilistic Neural Network (PNN) technique to derive the orbital parameters of spectroscopic binary stars. Using measured radial velocity data of five double-lined spectroscopic binary systems (i.e., EQ Tau, V376 And, V776 Cas, V2377 Oph and EE Cet), we find the corresponding orbital and spectroscopic elements. Our numerical results are in good agreement with those obtained by other groups via more traditional methods.

Cataclysmic Variables — X-rays and Optical Activity in V1223 Sgr and V709 Cas

Intermediate polars are a major fraction of all cataclysmic variables detected by INTEGRAL in hard X-ray. These objects have recently been proposed to be the dominant X-ray source population detected near the Galactic centre, and they also contribute significantly to X-ray diffuse Galactic ridge emission. Nevertheless, only 25% of all known intermediate polars have been detected in hard X-ray. This fact can be related to the activity state of these close interacting binaries.A multi-frequency (from optical to X-ray) investigation of intermediate polars is essential for understanding the physical mechanisms responsible for the observed activity of these objects.

Optical Studies of 20 Longer-Period Cataclysmic Binaries11Based on observations obtained at the MDM Observatory, operated by Dartmouth College, Columbia University, Ohio State University, Ohio University, and the University of Michigan.

ABSTRACTWe obtained time-series radial-velocity spectroscopy of 20 cataclysmic variable stars, with the aim of determining orbital periods Porb. All of the stars reported here prove to have Porb > 3.5 h. For 16 of the stars, these are the first available period determinations, and for the remaining four (V709 Cas, AF Cam, V1062 Tau, and RX J2133 + 51), we use new observations to improve the accuracy of previously published periods. Most of the targets are dwarf novae, without notable idiosyncrasies. Of the remainder, three (V709 Cas, V1062 Tau, and RX J2133 + 51) are intermediate polars (DQ Her stars); one (IPHAS 0345) is a secondary-dominated system without known outbursts, similar to LY UMa; one (V1059 Sgr) is an old nova; and two others (V478 Her and V1082 Sgr) are long-period novalike variables. The stars with new periods are IPHAS 0345 (0.314 days); V344 Ori (0.234 days); VZ Sex (0.149 days); NSVS 1057 + 09 (0.376 days); V478 Her (0.629 days); V1059 Sgr (0.286 days); V1082 Sgr (0.868 days); FO Aql (0.217 days); V587 Lyr (0.275 days); V792 Cyg (0.297 days); V795 Cyg (0.181 days); V811 Cyg (0.157 days); V542 Cyg (0.182 days); PQ Aql (0.247 days); V516 Cyg (0.171 days); and VZ Aqr (0.161 days). Noteworthy results on individual stars are as follows. We see no indication of the underlying white dwarf star in V709 Cas, as has been previously claimed; based on the nondetection of the secondary star, we argue that the system is farther away that had been thought and the white dwarf contribution is probably negligible. V478 Her had been classified as an SU UMa-type dwarf nova, but this is incompatible with the long orbital period we find. We report the first secondary-star velocity curve for V1062 Tau. In V542 Cyg, we find a late-type contribution that remains stationary in radial velocity, yet the system is unresolved in a direct image, suggesting that it is a hierarchical triple system.

Physical parameters of components in close binary systems - VII

We present results of the modelling of multicolour light curves of 10 contact binary systems: V376 And, V523 Cas, CC Com, BX Dra, FG Hya, UZ Leo, XY Leo, AM Leo, EX Leo and RT LMi. The solutions resulted in a contact configuration for all systems. We found only FG Hya and UZ Leo to be in deep contact, the latter almost filling the outer critical lobe. The absolute parameters of the components have been determined with an accuracy of about a few per cent based on combined photometric and radial velocity curves, enlarging the sample of systems to 58 for which the physical parameters have been obtained in a uniform way. All but three systems (BX Dra, AM Leo and RT LMi) show asymmetries and peculiarities in the observed light curves, interpreted as resulting from their magnetic activity.

Photometric Observations of the Contact Binary System V523 Cassiopeiae

A total of 583 observations (193 in <TEX>${\Delta}b$</TEX>, 190 in <TEX>${\Delta}v$</TEX>, 200 in <TEX>${\Delta}r$</TEX>) for V523 Cas was made on 9 nights from September to December in 2008 using the 100 cm telescope with 2K CCD camera of the Chungbuk National University Observatory. With our data BVR light curves were constructed and 9 times of minimum light were determined. We also obtained physical parameters of the V523 Cas system by analysis of the BVR light curves using the Wilson-Devinney code.

Velocity curve studies of spectroscopic binary stars V380 Cygni, V401 Cyg, V523 Cas, V373 Cas and V2388 Oph

Using measured radial velocity data of five double lined spectroscopic binary systems V380 Cygni, V401 Cyg, V523 Cas, V373 Cas and V2388 Oph, we find corresponding orbital and spectroscopic elements via the method introduced by Karami & Mohebi (2007) and Karami & Teimoorinia (2007). Our numerical results are in good agreement wit. those obtained by others using more traditional methods.

Absolute dimensions of the close binary systems V453 Monocerotis and V523 Cassiopeiae

We present multi-colour CCD observations of the low-temperature contact binaries, V453 Mon and V523 Cas. Their light curves are modelled to determine a new set of stellar and orbital parameters. Analysis of mid-eclipse times yields a new linear ephemeris for both systems. A period decrease (dP/dt=2.3×10−7 days/yr) in V453 Mon is discovered. V523 Cas, however, is detected to show a period increase (dP/dt=9.8×10−8 days/yr) because of the mass transfer of a rate of 1.1×10−7 M⊙ yr−1, from a less massive donor. Using these findings we can determine the physical parameters of the components of V523 Cas to be M 1=0.76 (3)M ⊙, M 2=0.39 (2)M ⊙, R 1=0.74 (2)R ⊙, R 2=0.55 (2)R ⊙, L 1=0.19 (3)L ⊙, L 2=0.14 (3)L ⊙, and the distance of system as 46(9) pc.

Analysis of the white-light flickering of the intermediate polar V709 Cassiopeiae with wavelets and Hurst analysis

We characterize the flickering observed in the optical lightcurve of the Intermediate Polar system V709 Cas by determining its position in the alpha-Sigma as in the Fritz and Bruch (1998) classification scheme. Sigma represents the strength of flickering at a given timescale, while alpha describes the energy distribution of the flickering at different time scales. Here alpha is independently obtained with both the wavelets and the Hurst R/S analysis. The flickering shows self-similarity in the time scale ranging from tens of minutes down to 10 seconds with stochastic persistent memory in time. alpha and Sigma appear anticorrelated. In the alpha-Sigma diagram V709 Cas falls in the region of magnetic systems. Since V709 Cas shows the spin period of the magnetic WD only in the X-ray but not in the optical, we conclude that this method can be used to characterize CV subtypes especially when their classification is uncertain.

OBSERVATIONS OF V592 CASSIOPEIAE WITH THESPITZER SPACE TELESCOPE—DUST IN THE MID-INFRARED

We present the ultraviolet-optical-infrared spectral energy distribution of the low inclination novalike cataclysmic variable V592 Cassiopeiae, including new mid-infrared observations from 3.5-24 microns obtained with the Spitzer Space Telescope. At wavelengths shortward of 8 microns, the spectral energy distribution of V592 Cas is dominated by the steady state accretion disk, but there is flux density in excess of the summed stellar components and accretion disk at longer wavelengths. Reproducing the observed spectral energy distribution from ultraviolet to mid-infrared wavelengths can be accomplished by including a circumbinary disk composed of cool dust, with a maximum inner edge temperature of ~500 K. The total mass of circumbinary dust in V592 Cas (~10^21 g) is similar to that found from recent studies of infrared excess in magnetic CVs, and is too small to have a significant effect on the long-term secular evolution of the cataclysmic variable. The existence of circumbinary dust in V592 Cas is possibly linked to the presence of a wind outflow in this system, which can provide the necessary raw materials to replenish the circumbinary disk on relatively short timescales, and/or could be a remnant from the common envelope phase early in the formation history of the system.

INTEGRAL/IBIS andSwift/XRT observations of hard cataclysmic variables

The analysis of the third INTEGRAL/Imager on Board Integral Satellite (IBIS) survey has revealed several new cataclysmic variables, most of which turned out to be intermediate polars, thus confirming that these objects are strong emitters in hard X-rays. Here, we present high-energy spectra of all 22 cataclysmic variables detected in the third IBIS survey and provide the first average spectrum over the 20–100 keV band for this class. Our analysis indicates that the best-fitting model is a thermal bremsstrahlung with an average temperature of ?kT?? 22 keV . Recently, 11 (10 intermediate polars and one polar) of these systems have been followed up by Swift/X-ray telescope (XRT) (operating in the 0.3–10 keV energy band), thus allowing us to investigate their spectral behaviour over the range ?0.3–100 keV. Thanks to this wide energy coverage, it was possible for these sources to simultaneously measure the soft and hard components and estimate their temperatures. The soft emission, thought to originate in the irradiated poles of the white dwarf atmosphere, is well described by a blackbody model with temperatures in the range ?60–120 eV. The hard emission, which is supposed to be originated from optically thin plasma in the post-shock region above the magnetic poles, is indeed well modelled with a bremsstrahlung model with temperatures in the range ?16–35 keV, similar to the values obtained from the INTEGRAL data alone. In several cases, we also find the presence of a complex absorber: one totally [with NH? (0.4– 28) × 1021 cm?2 ] and one partially [with NH? (0.7–9) × 1023 cm?2 ] covering the source. Only in four cases (V709 Cas, GK Per, IGR J06253+7334 and IGR J17303?0601), we find evidence for the presence of an iron line at 6.4 keV. We discuss our findings in the light of the systems parameters and cataclysmic variables/intermediate polars modelling scenario.

Velocity-Curve Analysis of the Spectroscopic Binary Stars V373 Cas, V2388 Oph, V401 Cyg, GM Dra, V523 Cas, AB And and HD 141929 by Artificial Neural Networks

AbstractWe used an Artificial Neural Network (ANN) to derive the orbital parameters of spectroscopic binary stars. Using measured radial velocity data of seven double-lined spectroscopic binary systems V373 Cas, V2388 Oph, V401 Cyg, GM Dra, V523 Cas, AB And and HD 141929, we found corresponding orbital and spectroscopic elements. Our numerical results are in good agreement with those obtained by others using more traditional methods.

OBSERVATIONS OF V592 CAS—AN OUTFLOW AT OPTICAL WAVELENGTHS

We present new red optical spectra of V592 Cas aimed at exploring the properties of the outflow of this system in a spectral region where the underlying white dwarf and the accretion disk do not contribute significantly to the observed absorption components of the H-alpha and HeI line profiles. We use the H-alpha emission line to study the wind, which appears as pronounced blueshifted P-Cygni absorption troughs whose low velocity end contaminates the blue side of the emission line profile. The wind appears to be episodic in nature, with multiple events reaching velocities of 5000km/sec in H-alpha. Similar (but weaker) wind signatures appear in the HeI5876AA line but are absent in HeI6678AA. Our data suggest that during wind episodes the wind is phase dependent and is visible for half the orbit of the system. Considering that V592 Cas is viewed almost face-on, the symmetry axis of the outflow can not be orthogonal to the disk and/or the outflow must have some other inherent asymmetry in outflow geometry. A possible origin of the wind is in a disk hotspot, either at the initial impact point of the accretion stream on the disk edge or as a result of disk overflow (similar to SW Sextantis stars). Simultaneous optical photometry during one night of our spectroscopic observations indicate that there is no clear relationship between the optical brightness variations and the strength of the outflow in this system.