Photometric and spectral studies of the eclipsing polar CRTS CSS081231 J071126+440405

We present the results of the study of the eclipsing polar CRTS CSS081231 J071126+440405. Photometric observations allowed us to refine the orbital period of the system \(P_ \circ = 0_ \cdot ^d 0.08137673\). Considerable changes in the appearance of the object’s spectra have occurred over the period of September 20–21, 2001: the slope of the continuum changed from “red” to “blue”, and the variability of the line profiles over the duration of the orbital period has also changed. Doppler maps have shown a shift of the emission line-forming region along the accretion stream closer to the white dwarf. We measured the duration of the eclipse of the system and imposed constraints on the inclination angle \(78_ \cdot ^ \circ 7 < i < 79_ \cdot ^ \circ 3\). The derived radial velocity amplitude was used to obtain the basic parameters of the system: M₁ = 0.86 ± 0.08M_⊙, M₂ = 0.18 ± 0.02 M_⊙, q = 0.21 ± 0.01, R_L2 = 0.20 ± 0.03 R_⊙, A = 0.80 ± 0.03 R_⊙. The spectra of the object exhibit cyclotron harmonics. Their comparison with model spectra allowed us to determine the parameters of the accretion column: B = 31–34 MG, T_e = 10–12 keV, θ = 80–90°, and Λ = 10⁵.     

CSS091109:035759+102943: A candidate polar

We report optical time‐resolved photometry of the CRTS transient CSS091109:035759+102943. Pronounced orbital variability with a 114 min period, large X‐ray variability and the IR to X‐ray spectral energy distribution suggest a classification as a magnetic cataclysmic binary, a likely AM Herculis star or polar (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

First photometric analysis of the two EW binaries ZTF J214226.88+435827.1 and KAO-EGYPT J214216.38+440015.1

The EW-type eclipsing binaries are strongly interacting systems known to have often both component stars filling their crucial Roche lobes and having a common envelope. We present new BVRI light curves of the eclipsing binaries ZTF J214226.88+435,827.1 (ZTF21+43) and KAO-EGYPT J214216.38+440,015.1 (KAO21+44) based on CCD observations acquired with the 1.88-m Kottamia Astronomical Observatory (KAO) at Newtonian and Cassegrain telescope focus. The modeling results show that these two systems are to be W UMa contact binaries belonging to EW subtypes. All the light curves show the inverse O'Connell effect. We computed new ephemeris for each system using our times of minima and that available in the literature. Using our new times of minima and epochs for both systems from all available observations, the orbital period changes of these structures are studied for our systems. Using the PHOEBE package, a preliminary determination of the two systems' photometric orbital and physical parameters has been present. The positions of the systems were also depicted on the Hertzsprung-Russell (H-R), M-L, and T_eff-L diagrams to test their evolutionary status.     

Discovery of the high-field polar RX J1724.0+4114

We report the discovery of a new AM Herculis binary (polar) as the optical counterpart of the soft X-ray source RX J1724.0+4114 detected during the ROSAT all-sky survey. The magnetic nature of this V  ∼ 17 mag object is confirmed by low-resolution spectroscopy showing strong Balmer and He  II emission lines superimposed on a blue continuum, which is deeply modulated by cyclotron humps. The inferred magnetic field strength is 50 ± 4 MG (or possibly even ≈ 70 MG). Photometric observations spanning ∼ 3 yr reveal a period of 119.9 min, directly below the period gap. The morphology of the optical and X-ray light curves, which do not show eclipses by the secondary star, suggests a self-eclipsing geometry. We derive a lower limit on the distance of d  ≳ 250 pc.     

CSS J075415.6+191052 and NW Leo:Two Contact Binaries at Different Evolutionary Stages

Multi-color light curves of CSS J075415.6+191052 and NW Leo are presented and the photometric solutions suggest that CSS J075415.6+191052 is an A-subtype contac...     

First photometric study of ultrashort-period contact binary 1SWASP J140533.33+114639.1

In this paper,CCD photometric light curves for the short-period eclipsing binary 1 SWASP J140533.33+114639.1(hereafter J1405) in the BV R bands are presented and analyzed using the 2013 version of the Wilson-Devinney(W-D) code. It is discovered that J1405 is a W-subtype shallow contact binary with a contact degree of f = 7.9±0.5% and a mass ratio of q = 1.55±0.02. In order to explain the asymmetric light curves of the system,a cool starspot on the more massive component is employed. This shallow contact eclipsing binary may have been formed from a short-period detached system through orbital shrinkage due to angular momentum loss. Based on the(O-C) method,the variation of orbital period is studied using all the available times of minimum light. The(O-C) diagram reveals that the period is increasing continuously at a rate of d P/dt = +2.09×10~(-7) d yr~(-1),which can be explained by mass transfer from the less massive component to the more massive one.     

Spectral and photometric observations of the star Y Ori

Data are presented from a spectral and photometric study of the long-period variable star Y Ori, which we have classified as a type M7IIIe near its brightness minimum. In the blue part of the spectrum, features from a star of an earlier spectral class are superimposed on the spectrum of a cool giant, so that a variable excess emission is observed at wavelengths of 4000–4200 Å. As opposed to the monotonically decreasing intensity of the Balmer lines (EWHα > EWHβ > EWHγ > EWHδ) in normal stars belonging to the earlier spectral classes, a reverse relationship, with EWHγ < EWHδ is detected in Y Ori. Translated from Astrofizika, Vol. 51, No. 4, pp. 567–575 (November 2008).     

Multi‐epoch time‐resolved photometry of the eclipsing polar CSS081231:071126+440405

The eclipsing polar CSS081231:071126+440405 turned bright (V_max ∼ 14.5) in late 2008 and was subsequently observed intensively with small and medium‐sized telescopes. A homogeneous analysis of this comprehensive dataset comprising 109 eclipse epochs is presented and a linear ephemeris covering the five years of observations, about 24000 orbital cycles, is derived. Formally this sets rather tight constraints on the mass of a hypothetical circumbinary planet, M_pl ≤ 2 M_Jup. This preliminary result needs consolidation by long‐term monitoring of the source. The eclipse lasts 433.08 ± 0.65 s, and the orbital inclination is found to be i = 79.3°–83.7°. The centre of the bright phase displays accretion‐rate dependent azimuthal shifts. No accretion geometry is found that explains all observational constraints, suggesting a complex accretion geometry with possible pole switches and a likely non‐dipolar field geometry. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Photometric observations and light curve solutions of the W UMa stars NSVS 2244206, NSVS 908513, CSS J004004.7+385531 and VSX J062624.4+570907

Photometric observations in Sloan g' and i' bands of four W UMa stars,NSVS 2244206,NSVS908513,CSS J004004.7+385531 and VSX J062624.4+570907,are presented.The light curve solutions reveal that all targets have overcontact configurations with fillout factors within 0.15-0.26.Their components are G-K spectral types and are almost in thermal contact.They are also relatively close in size and luminosity:the radius ratios r_2/r_1 are within 0.75-0.90;the luminosity ratios l_2/l_1 are within 0.53-0.63.The results of the light curve solution of CSS J004004.7+385531 imply the weak limb-darkening effect of its primary component and possible presence of additional absorbing features in the system.     

Spectral and photometric study of compact groups of compact galaxies

Results are presented from a spectral, photometric, and morphological study of two compact groups of compact galaxies (CGCG) from Shahbazian’s list. The observations were made on the 1.5-m ESO telescope and the 2.6-m telescope at the Byurakan Astrophysical Observatory (BAO) during 1999–2000. These data are compared with data for the Shahbazian compact group 4. A high spatial density of galaxies, ranging from 10000 to 100000 galaxies per Mpc³, is observed in all the groups that were studied. The discovery of a Seyfert Sy1 galaxy in the Shahbazian 355 compact group is especially noteworthy. The direct photographs of the CGCGs that were studied contain no signs of merging or tidal interactions among the members of these groups. This suggests that the galaxies in these dense systems have a common origin. __________ Translated from Astrofizika, Vol. 50, No. 3, pp. 347–353 (August 2007).     

Spectral and photometric observations of TT Ari. III.

The nova-like cataclysmic variable (CV) TT Ari was detected in its second deep minimum in November 2009. Study of its evolutionary phase is very important for research on the nature of CVs in the VY Scl group. During this phase the spectral energy distribution of the star changed rapidly. The emission lines of elements with high excitation, such as HeII λ4686 and NIII/CIII, as well as broad absorption in the hydrogen Balmer series, originating in the photosphere of the white dwarf or in the lower layers of an accretion disk, vanished. The average ratio of the intensities of the Balmer series emission lines in the normal state and in the deep low state can be explained in terms of a simple photoionization-recombination model. At the same time, the intensity ratios of the triplet-singlet levels of neutral helium, HeIλ5876/ HeIλ6678, differ greatly in the normal state of the star and in its deep minimum. In the deep minimum, the star’s spectrum contains only a very faint trace of the G band at a wavelength λ4300?, together with flarelike events with amplitudes up to Δm ≈ 2^m.0 or greater. These and some other observed characteristics indicate that during the deep minimum it is mainly emission from the secondary companion of the binary system, which is probably a T Tau star of an early K spectral class, that is observed.     

A photometric study of the polar ring galaxy UGC 5600

We analyze our BVR _c photometry for UGC 5600, a candidate polar ring galaxy, obtained with the 6-m telescope. We have confirmed the existence of an inner polar ring and show that the outer ring-shaped structure represents spiral arms; i.e., UGC 5600 belongs to the rare class of gas-rich spiral galaxies with inner polar rings.     

Spectral and photometric behavior of SU UMa during quiescence and outburst states

We report the results of spectral and photometric observations of SU UMa. Available spectra from International Ultraviolet Explorer (IUE) and CCD photometry of five nights were used. Some profiles revealing the variations of some spectral lines at different times are presented. There is variation with time for photometric observations and the brightness of SU UMa is changed from 12.9 mag. to 15.6 mag in 5 nights with clear display of burst. The ultraviolet luminosity for emitting region is in the range of (6.9*10³⁰ erg s⁻¹). The mass accretion rate is in the range of (9.8*10⁻¹³ M_⊙yr⁻¹). The line flux modulations at different times can be explained in terms of the mass transfer instability model (Bath 1973).     

Swift observations of CSS081007:030559+054715

CSS081007:030559+054715 was discovered by the Catalina Real‐time Transient Survey. Optical spectroscopy revealed a multi‐peaked Hα emission line profile with radial velocities exceeding 1500 km/s, as well as strong Ne emission, suggestive of a neon nova. We monitored the source extensively with the Swift satellite, obtaining a unique dataset spanning 270 days in the soft X‐ray and UV bands. The data reveal a soft, blackbody‐like spectrum with a temperature around 55 eV (though dependent on the modelling), variable X‐ray and UV light curves with a 1.77 day period in both the X‐ray and UV bands, a longer timescale modulation of ∼ 50 days, followed by a slowly declining trend in the soft X‐ray and UV flux. We highlight the Swift observations and their implications for the SSS nature of this object (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Photometric and Spectroscopic Study of Two Low Mass Ratio Contact Binary Systems: CRTS J225828.7-121122 and CRTSJ030053.5+230139

The study reports photometric and spectroscopic observations of two recently recognized contact binary systems.Both systems show total eclipses and analysis of the light curves indicates both have very low mass ratios of less than 0.3. We derive absolute parameters from color and distance based calibrations and show that, although both have low mass ratios, they are likely to be in a stable orbit and unlikely to merge. In other respects, both systems have characteristics similar to other contact...     

Spectral and photometric monitoring of distant core-collapse supernovae in the SAO RAS

This paper describes the aims, objectives and first results of the observational program for the study of distant core-collapse supernovae (SNe) with redshifts z ≲ 0.3. This work is done within the framework of an international cooperation program on the SNe monitoring at the 6-m BTA telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences, and other telescopes. We study both the early phases of events (SN type determination, redshift estimation, and a search for manifestations of a wind envelope), and the nebular phase (the effects of explosion asymmetry). The SNe, associated with cosmic gamma-ray bursts are of particular interest. An interpretation of our observational data along with the data obtained on other telescopes is used to test the existing theoretical models of both the SN explosion, and the surrounding circumstellar medium. In 2009 we observed 30 objects; the spectra were obtained for 12 of them. We determined the types, phases after maximum, and redshifts for five SNe (SN 2009db, SN 2009dy, SN 2009dw, SN 2009ew, SN 2009ji). Based on the obtained photometric data a discovery of two more SNe was confirmed (SN 2009bx and SN 2009cb). A study of two type II supernovae in the nebular phase (SN 2008gz and SN 2008in) is finalized, four more objects (SN 2008iy, SN 2009ay, SN 2009bw, SN 2009de) are currently monitored.     

Spectroscopic and photometric studies of the magnetic cataclysmic variable EU UMa (=RE1149+28)

We present the optical observations of the AM Herculis system EU UMa (=RE1149+28) carried out in February 1993 with a TV scanner and a photometer (NEPh) at the secondary focus of the 6-m Special Astrophysical Observatory telescope. Spectroscopy with a time resolution of 300 s and a spectral resolution of 2 Å in the wavelength range ≈3950–4950 Å is used to analyze the variability of emission-line profiles, equivalent widths, central intensities R_c, and radial velocities with orbital phase. We determined the orbital period of the system from line radial-velocity measurements, 90.0±0.2 min. The emission-line profiles are highly variable. The Hβ and He II 4686 Å lines exhibit P Cyg profiles at selected phases. The spectral-line parameters were found to vary significantly on time scales from 5 to 15 min. The possible causes of the detected spectroscopic variability are discussed.     

Multiband photometric detection of a huge flare on the M9 dwarf 2MASSW J1707183+643933

We present simultaneous UV , G , R and I monitoring of 19 M dwarfs that reveal a huge flare on the M9 dwarf with an amplitude in the UV of at least 6 mag. This is one of the strongest detections ever of an optical flare in an M star and one of the first in an ultracool dwarf (spectral types later than about M7). Four intermediate-strength flares  (Δ m _UV < 4 mag)  were found in this and three other targets. For the whole sample we deduce a flare probability of 0.013 (rate of  0.022 h⁻¹  ), and  0.049 (0.090 h⁻¹)  for 2M1707+64 alone. Deviations of the flare emission from a blackbody is consistent with strong  Hα  line emission. We also confirm our previously found rotation period for 2M1707+64 and determine it more precisely to be  3.619 ± 0.015 h  .     

Spectral ageing analysis of the double–double radio galaxy J1453+3308

We present new radio observations at frequencies ranging from 240 to 4860 MHz of the well-known, double–double radio galaxy (DDRG), J1453+3308, using both the Giant Metrewave Radio Telescope (GMRT) and the Very Large Array (VLA). These observations enable us to determine the spectra of the inner and outer lobes over a large frequency range and demonstrate that while the spectrum of the outer lobes exhibits significant curvature, that of the inner lobes appears practically straight. The break frequency, and hence the inferred synchrotron age of the outer structure, determined from 16-arcsec strips transverse to the source axis, increases with distance from the heads of the lobes. The maximum spectral ages for the northern and southern lobes are ∼47 and 58 Myr, respectively. Because of the difference in the lengths of the lobes, these ages imply a mean separation velocity of the heads of the lobes from the emitting plasma of 0.036 c for both the northern and southern lobes. The synchrotron age of the inner double is about 2 Myr which implies an advance velocity of ∼0.1 c , but these values have large uncertainties because the spectrum is practically straight.