Physical properties and CNO abundances for high-mass stars in four main-sequence detached eclipsing binaries: V478 Cyg, AH Cep, V453 Cyg, and V578 Mon

We present ten high-precision light curves of four transits in the XO-1 planetary system, obtained using u, g, r, redshifted Hα, I and z filters. We use these to measure the physical properties, orbital ephemeris, and a transmission spectrum of the planet covering the full optical wavelength range. We augment this with published HST/WFC3 observations to construct a transmission spectrum of the planet covering 0.37 to 1.65 μm. Our best-fitting model to this spectrum is for a H2/He-rich atmosphere containing water (3.05σ confidence), nitrogen-bearing molecules NH3 and HCN (1.5σ) and patchy cloud (1.3σ). We find that adding the optical to the near-infrared data does not lead to more precise constraints on the planetary atmosphere in this case. We conduct a detailed investigation into the effect of stellar limb darkening on our results, concluding that the choice of limb darkening law and coefficients is unimportant; such conclusions may not hold for other systems so should be reassessed for all high-quality datasets. The planet radius we measure in the g-band is anomalously low and should be investigated with future observations at a higher spectral resolution. From the measured times of transit we determine an improved orbital ephemeris, calculate a lower limit on the modified stellar tidal quality factor of Q′⋆>105.6, and rule out a previously postulated sinusoidal variation in the transit times

BF Cyg during ITS current outburst

We are intensively monitoring the current outburst on BF Cyg, both spectroscopically (high and low resolution modes) and photometrically (so far 450 BVRCRIC measurements have been collected). The outburst is photometrically reminiscent of the major event BF Cyg experienced in 1890 when it rose by 4 mag in the blue. In this contribution we present the data and describe the plans to investigate this object

BF Cyg During its Current Outburst

AbstractWe are intensively monitoring the current outburst on BF Cyg, both spectroscopically (high and low resolution modes) and photometrically (so far 450 BV

Abell-35 phenomena in symbiotic stars: Discovery of 1.2 and 6.4 day periods in VV8 (V471 per)

We have collected high precision optical photometry of VV8, so far 782 individual observing runs uniformly distributed over the period 2005-2011. This dataset allows us to refine the known long periodicity of VV8 to P = 16.8 yr, with peak-to-valley amplitudes of ΔB = 0.18 and ΔV = 0.14 mag. In addition, we have discovered two new periodicities: 6.431 d (total amplitude Δ = ΔV = ΔI= 0.05 mag) and 1.185 d (ΔB = 0.022, ΔV = 0.018, ΔI = 0.014 mag). These two short periods are reminiscent of the Abell35 phenomena displayed by binary nuclei of planetary nebulae that have gone through a common envelope phase. Twice the 6.431 d period would nicely correspond to the double-peaked light-curve that the G5 III star in VV8 would display if its Roche lobe would be ellipsoidally distorted

Velocity-resolved reverberation mapping of five bright Seyfert 1 galaxies

We present the first results from a reverberation-mapping campaign undertaken during the first half of 2012, with additional data on one AGN (NGC 3227) from a 2014 campaign. Our main goals are (1) to determine the black hole masses from continuum-Hβ reverberation signatures, and (2) to look for velocity-dependent time delays that might be indicators of the gross kinematics of the broad-line region. We successfully measure Hbeta time delays and black hole masses for five AGNs, four of which have previous reverberation mass measurements. The values measured here are in agreement with earlier estimates, though there is some intrinsic scatter beyond the formal measurement errors. We observe velocity dependent Hβ lags in each case, and find that the patterns have changed in the intervening five years for three AGNs that were also observed in 2007.PostprintPeer reviewe

Constrained fitting of disentangled binary star spectra: application to V615 Persei in the open cluster h Persei

Context. Using the technique of spectral disentangling, it is possible to determine the individual spectra of the components of a multiple star system from composite spectra observed at a range of orbital phases. This method has several advantages: it is unaffected by line blending, does not use template spectra, and returns individual component spectra with very high signal-to-noise ratios. Aims. The disentangled spectra of a binary star system are very well suited to spectroscopic analysis but for one problem: the absolute spectral line depths are unknown because this information is not contained in the original spectra (unless there is one taken in eclipse) without making assumptions about the spectral characteristics of the component stars. Here we present a method for obtaining the atmospheric parameters of the component stars by the constrained fitting of synthetic spectra to observed and disentangled spectra. Methods. Disentangled spectra are fitted using synthetic spectra and a genetic algorithm in order to determine the effective temperatures, surface gravities and relative light contributions of the two stars in a binary system. The method is demonstrated on synthetic spectra and then applied to the eclipsing binary V615 Per, a member of the young open cluster NGC 869 (h Persei). Results. The method works well for disentangled spectra with signal-to-noise ratios of 100 or more. For V615 Per we find a normal He abundance but an Mg abundance, which indicates bulk metallicity, a factor of two lower than typical for nearby OB stars

Spectral disentangling of the metallic-lined binary system WW Aurigae

WW Aurigae is doubled-lined eclipsing binary system. Both components show Am characteristics. Recently, Southworth et al. (2005) measured the properties of WW Aur with accuracies of 0.4% in mass and 0.6% in radius, making these among the most accurately known for any stars except the Sun. These properties are matched by theoretical evolutionary models only for a high (2.5 times solar) metal abundance. In a continuation of that study, we have reanalysed the time-series of 57 double-lined spectra (from the INT at La Palma) using spectral disentangling to obtain high-quality separated spectra of the two stars. Our goal is to further improve the determination of the effective temperatures and to study the peculiar chemical abundances of the two stars

BF Cyg During its Current Outburst

We are intensively monitoring the current outburst on BF Cyg, both spectroscopically (high and low resolution modes) and photometrically (so far 450 BVRCRIC measurements have been collected). The outburst is photometrically reminiscent of the major event BF Cyg experienced in 1890 when it rose by 4 mag in the blue. In this contribution we present the data and describe the plans to investigate this object