We present the first results of a comprehensive photometric O-star survey performed with a robotic twin refractor at the Universitatssternwarte Bochum located near Cerro Armazones in Chile. For three high-mass stars, Pismis 24-1, CPD-51 8946, and HD 319702, we determined the period through the Lafler-Kinman algorithm and modelled the light curves within the framework of the Roche geometry.
EE Aqr is a 7.9mag Algol variable with a 12hr orbital period. The Wilson-Devinney program is used to simultaneously solve 11 previously published light curves together with two existing radial velocity curves. The resulting masses are M_1_=2.24+/-0.13M_{sun}_ and M_2_=0.72+/-0.04M_{sun}_, and the radii are R_1_=1.76+/-0.03R_{sun}_ and R_2_=1.10+/-0.02R_{sun}_. The system has the lower-mass component completely filling its Roche lobe. Its distance from Hipparcos observations is 112+/-10pc. An improved ephemeris is derived, and no deviations in the period over time were seen. Light and velocity curve parameters, orbital elements, and absolute dimensions are presented, plus a comparison is made with previous solutions.
Bipolar planetary nebulae (PNe) are thought to result from binary star interactions and, indeed, tens of binary central stars of PNe have been found, in particular using photometric time-series that allow detecting post-common envelope systems. Using photometry at the NTT in La Silla we have studied the bright object close to the centre of PN M3-2 and found it to be an eclipsing binary with an orbital period of 1.88 days. However, the components of the binary appear to be two A or F stars, of almost equal masses, and are thus too cold to be the source of ionisation of the nebula. Using deep images of the central star obtained in good seeing, we confirm a previous result that the central star is more likely a much fainter star, located 2 arcsec away from the bright star. The eclipsing binary is thus a chance alignment on top of the planetary nebula. We also studied the nebular abundance and confirm it to be a Type I PN.
Structure of the wind from the cool giants in symbiotic binaries carries important information for understanding the wind mass transfer to their white dwarf companions, its fuelling, and thus the path to different phases of symbiotic-star evolution. In this paper we indicate a non-spherical distribution of the neutral wind zone around the red giant (RG) in the symbiotic binary star EG And. In particular, its focusing towards the orbital plane and the asymmetry alongside the orbital motion of the RG. We achieved this aim by analysing the periodic orbital variations of fluxes and radial velocities of individual components of the H_alpha and [OIII] lambda 5007 lines observed on our high-cadence medium (R~11000) and high-resolution (R~38000) spectra. The asymmetric shaping of the neutral wind zone at the near-orbital-plane region is indicated by: (i) the asymmetric course of the Halpha core emission fluxes along the orbit, (ii) the presence of their secondary maximum around the orbital phase phi=0.1 possibly caused by the refraction effect, and (iii) the properties of the H_alpha broad wing emission originating by Raman scattering on H^0^ atoms. The wind is substantially compressed from polar directions to the orbital plane as constrained by the location of the [OIII] lambda 5007 line emission zones in the vicinity of the RG at/around its poles. The corresponding mass-loss rate from the polar regions of <~10^-8^M_{sun}_/yr is a factor of >~10 lower than the average rate of ~10^-7^M_{sun}_/yr derived from nebular emission of the ionized wind from the RG, and it is two orders of magnitude lower than that measured in the near-orbital-plane region from Rayleigh scattering. The startling properties of the nebular [OIII] lambda 5007 line in EG And provides an independent indication of the wind focusing towards the orbital plane -- the key to understanding the efficient wind mass transfer in symbiotic binary stars.
New CCD photometry for the eclipsing binary EH Cnc was made from 2009 to 2011, and five new eclipsing times are presented. Through using the updated Wilson-Devinney code, we first deduced the photometric solution at {chi}^2^=0.9906. The results show that EH Cnc is a W-type contact binary, whose mass ratio and overcontact degree are q=2.51(+/-0.02) and f=27.7%(+/-3.4%) , respectively.
A set of 442 eclipsing binaries was selected from the GCVS catalog (Kholopov et al., 2003) that had declination <0{deg}, minimum magnitude brighter than 13.0, and no published times of minima later than JD 2440000 available through the NASA ADS service. An automated web-based data gathering application was developed to retrieve and display data from the ASAS-3 database (Pojmanski, 2002, Cat. J/AcA/48/35>). A search radius of 45 arcsec was used when selecting candidate stars.
I identify the profusion of emission lines seen in IUE spectra of 32 Cyg (K4-5 Ib+B6-7 IV-V) during total eclipse. With the exception of a very few weak lines, all of these are also seen in zeta Aur during its eclipse, and the stronger features appear in 31 Cyg. Seventy-four percent of these emission lines can be attributed to FeII. Few are intrisically weaker than gf~0.01. Other spectra definitely present are CII, NI, OI, SiII, MgII, SII, CrII, NiII, AlII, AlIII, FIII, SiIV, and CIV. No emission lines of the neutral metals, except for fluorescent FeI UV44, are unambiguously detected; specifically, lines of CI, SiI, or SI were not detected in the spectrum.
