D. Cieslinski

Optical polarimetry and infrared photometry of two AM Her binaries: 1RXS J161008.0+035222 and 1RXS J231603.9−052713

We present the first optical circular and linear polarizatio n measurements of two polar candidates from ROSAT: 1RXS J161008.0+035222 and 1RXS J231603.9 052713. We also present H band near-infrared photometry of the last object. The presence of strong circular polarization confirms them as AM Her systems. 1RXS J231603.9 052713 was observed in two different brightness states. The orbital phase dependence of the flux and polarization of 1RXS J161008.0+035222 is reasonably fitted with a simple mod el in which the binary is observed at a small inclination and the magnetic field axis is al most parallel to the white-dwarf rotation axis resulting in the accretion column axis being s een from top during the whole orbital revolution. An alternative geometry with intermediate inclination can fit the observed flux and circular polarization. However, in this case, the mo del produces a linear polarization peak which is not corroborated by the data. The estimated magnetic field is in the 10 to 20 MG range. The circular polarization of 1RXS J231603.9 052713 is complex and highly variable. The light-curves of that object have been fitted using a model which includes the white-dwarf, a heated secondary and a point-like accretion region. The secondary emission contributes significantly even in optical wavelengths. This model also repr oduces the main features of the optical polarization of 1RXS J231603.9 052713. We estimate the main parameters of the binary, of the accretion region and the distance to the syste m. An improved description of this system should include an extended and inhomogeneous accreting region as well as non-radial accretion.

Identification of New Eruptive Cataclysmic Variables toward the Galactic Bulge and Magellanic Clouds Using the OGLE-II Database

We have performed a search in the OGLE-II light-curve database in order to find new cataclysmic variables. The objects were selected from Magellanic Clouds and Galactic bulge variables, using photometric amplitude as the primary criterion. Nova or dwarf nova-type eruptions were recognized in many candidates, yielding a total of 33 new dwarf novae and two new classical novae identifications. All selected target positions were cross-correlated against X-ray survey databases in a search for possible point-source identifications. The main light-curve characteristics of each cataclysmic variable identified are described; when possible, a classification in a subtype was assigned to the system. We also find possible candidates to symbiotics, R Coronae Borealis, and RV Tauri. The detected dwarf novae in the direction of the bulge are likely members of the Galactic disk. Using our sample, one may derive an upper limit for the dwarf nova spatial density of 5 × 10-7 pc-3.

A SPECTROSCOPIC STUDY OF V617 SAGITTARII

We present the results of an analysis of time-resolved spectroscopy of V617 Sgr, the Wolf-Rayet star WR 109, in the Hβ and He II λ4686 region. Radial velocity curves were obtained confirming the orbital period of 4.97 hr found from photometric observations. These curves indicate that the superior conjunction of the line-forming region occurs close to the primary eclipse. Constraints on the stellar masses in this peculiar binary are derived from the emission lines. The orbital behavior of the emission line profiles is analyzed in detail. A Doppler tomography study of the Hβ and He II λ4686 lines is performed, aiming to estimate the locus of line formation in the system. The observations may suggest the presence of an optically thick wind. An extended emission region consistent with a hot spot and free-falling gas is also inferred from our analysis. The observed characteristics, such as the strong intensity of He II λ4686 (He II/Hβ flux ratio ~2.9) and the presence of emission lines of highly ionized elements like N V and O VI, are not usually seen in normal cataclysmic variables and, in this respect, V617 Sgr is quite similar to the star V Sge.

Assisted stellar suicide in V617 Sagittarii

Context. V617 Sgr is a V Sagittae star – a group of binaries thought to be the galactic counterparts of the Compact Binary Supersoft X-ray Sources – CBSS. Aims. To check this hypothesis, we measured the time derivative of its orbital period. Methods. Observed timings of eclipse minima spanning over 30 000 orbital cycles are presented. Results. We found that the orbital period evolves quite rapidly:

Optical polarimetric monitoring of the type II-plateau SN 2005af

P/\dot{P} = 1.1\times10^{6}

Stokes imaging of AM Her systems using 3D inhomogeneous models – II. Modelling X-ray and optical data of CP Tucanae

years. This is consistent with the idea that V617 Sgr is a wind driven accretion supersoft source. As the binary system evolves with a time-scale of about one million years, which is extremely short for a low mass evolved binary, it is likely that the system will soon end either by having its secondary completely evaporated or by the primary exploding as a supernova of type Ia. Conclusions.

The orbital period of the V Sge star candidate QU Carinae

Aims. Core-collapse supernovae may show significant polarization that implies non-spherically symmetric explosions. We observed the type II-plateau SN 2005af using optical polarimetry in order to verify whether any asphericity is present in the supernova temporal evolution. Methods. We used the IAGPOL imaging polarimeter to obtain optical linear polarization measurements in

MULTILINE DOPPLER IMAGING OF MR SER IN HIGH STATE

{\it R}

Exploratory Spectroscopy of Magnetic Cataclysmic Variables Candidates and Other Variable Objects

(five epochs) and

Concept of SPARC4:a simultaneous polarimeter and rapid camera in 4 bands

{\it V}