Pleione is a classical Be star well known for its cyclic transitions between Be-, shell- and normal B spectral phases. Its nature as a binary system was discussed by McAlister et al. (1989), Gies et al. (1990), Luthardt & Menchenkova (1994) and Nemravova et al (2010). We present the results that trace the evolution of the dimensions of the circumstellar disk of Pleione that are related to the binary system.

In the last decade great strides have been made in understanding the role of binary stars in the evolution and shaping of planetary nebulæ (PNe). Observational efforts have mainly focused on finding close binaries with orbital periods of 1 day or less. Those close binary systems make up around 1 in 5 PNe, and constitute the youngest accessible window into the aftermath of the critical and unobserved common-envelope (CE) phase of binary-star evolution. The poster focused on our recent work with the High Resolution Spectrograph (HRS) on the Southern African Large Telescope (SALT) to search for long-period binaries in PNe. Considerably less is known about such long-period binaries with orbital periods of weeks to years, but they may be fundamental to improving CE population synthesis models and for determining the total binary fraction of PNe. The queue-mode operation of SALT and the excellent sensitivity and stability of HRS (which is enclosed in a vacuum tank) are ideally suited to detecting binaries with low radial-velocity amplitudes over the expected timescales of weeks to years. Many exciting new discoveries about binaries have already been made in this newly-accessible southern horizon in time-domain astronomy thanks to the many unique advantages of SALT.

We 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.

We introduce a new computer program that is able to determine the flux ratio between the components of SB2 stars from time series of composite spectra. The spectra of the components are decomposed using the KOREL program and compared to synthetic spectra computed on a grid of fundamental stellar parameters. In the result, we obtain the optimized stellar parameters together with the flux ratio. The program is tested and applied to the oscillating eclipsing binary KIC 10661783 observed by the Kepler satellite mission.

We present current results from the ongoing WIYN Open Cluster Study radial-velocity survey for 1410 stars in the young (150 Myr) open cluster M35 (NGC 2168) and establish a benchmark for initial conditions in young open clusters. We find for periods ≲ 1000 days a minimum binary frequency of 0.36 – 0.51. We also analyze the spatial, period and eccentricity distributions of the binary systems and find that the period and eccentricity distributions are well approximated by scaled field distributions from Duquennoy & Mayor (1991). With our large sample size and long baseline, we have a unique understanding of the binary population in this young cluster, making it ideal for defining initial conditions for dynamical simulations.

We summarize the characteristics of 85 spectroscopic orbits derived from more than two decades of radial-velocity monitoring of stars in the old open cluster M 67, with special emphasis on the blue stragglers and other members that do not fall on the evolutionary tracks expected for isolated single stars.

Eta Carinae (ηCar), a Luminous Blue Variable, is a massive binary star system with a 5.54-year spectroscopic period. We present temporal surface plots of selected He I, H I, Fe II and [N II] stellar line profiles measured with HST/STIS sampled from 1998.0 to 2004.3. Our analysis suggests that the profile variations are due to 1) radial velocity variations of the primary star and 2) ionization effects due to the hot companion combined with its wind cavity.

High-resolution echelle spectroscopic observations taken with the FEROS spectrograph at the ESO 2.2-m telescope confirm the binary nature of the dMe stars EUVE J0825−16.3 and EUVE J1501−43.6, previously reported by Christian & Mathioudakis (2002). In these binary systems, emission of similar intensity from both components is detected in the Na i D1 & D2, He i D3, Ca II H&K, Ca II IRT and Balmer lines. We have determined precise radial velocities by cross-correlation with radial velocity standard stars, which have allowed us to obtain for the first time the orbital solution of these systems. Both binaries consist of two nearly equal M0V components with an orbital period shorter than 3.5 days. We have analyzed the behaviour of the chromospheric activity indicators (variability and possible flares). In addition, we have determined its rotational velocity and kinematics.

The parallax of the Pleiades has been mired in controversy ever since the very first astrometric measures in the late 1880s. Over a century later, the measures from the HIPPARCOS catalogue gave results which were inconsistent with the distance inferred from the fitting of the colour-magnitude diagram. We briefly review here the debate and focus on the various attempts made at solving the problem, and especially those using binary stars. The only double-lined eclipsing binary found so far in the Pleiades, HD 23642, provides not only the final answer to the problem but also, through detailed state-of-the-art analyses, the fundamental calibration for binaries in more distant clusters and hence in the Local Group. We discuss some of the various sources of systematic uncertainties that limit, so far, the accuracy of the measured stellar parameters to about 1% and the progress that is required to break this barrier.

The spectrum of the classical λ Boo star HD 204041 is revealed to be a composite one.

We present here a detailed study of FF UMa (2RE J0933+624), a recently discovered, X-ray/EUV selected, active binary system with strong Hα emission. By using high-resolution echelle spectroscopic observations taken during five observing runs from 1998 to 2004, we derived precise radial velocities that allowed us to determine the orbital solution of the system at different epochs. Analyzing these orbital solutions, together with a previous one determined in 1993 by other authors, we have found a change in the heliocentric Julian date on conjunction (Tconj) that can be explained by a change with time in the orbital period of the system. The relative amplitude of the orbital period variation derived from these data was dP/P ≈ 5 x 10−4, which is larger than the variations found in other similar chromospherically active binaries like AR Lac and HR 1099. This orbital period variation can be related (Applegate 1992; Lanza 1998, 2006) with the modulation of the gravitational quadrupole-moment of its magnetically active secondary star produced by angular momentum exchanges within its convective envelope. In addition, using these observations, we have determined the stellar parameters of the components and we have carried out a study of the chromospheric activity using all the optical indicators from Ca ii H&K to Ca ii IRT lines.

We report on the detection of secondary spectra in five spectroscopic binary systems: HD 434, HD 861, HD 108642, HD 178449, and HD 216608. High signal-to-noise high resolution spectroscopic observations were carried out at the Bulgarian NAO Rozhen as part of an extended project concerned mainly with Am stars in binary systems. Our knowledge about early type binaries has serious gaps. This is true especially when it is only based on older photographic techniques. We concluded that photographic data involving longer orbital periods (where Doppler shifts due to the orbital motion are comparable or even less than the rotational broadening of the spectral lines) and early type stars (that have only a few and usually broad lines) should be revisited or at least used with caution. We demonstrate that for the five systems how CCD observations made with 2-m class telescopes can discover the binary nature or secondary spectra of many currently unresolved SB1 systems. Important astrophysical information such as the atmospheric parameters and the mass ratios are used to unravel previous misinterpretations of the data leading often to spurious orbits.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Both components of the composite-spectrum binary o Leo have Am characteristics, even though the primary is an evolving giant ($\log g=3.25$) with $T_{\rm eff} \sim 6100\,{\rm K}$. This is believed to be the first isolation of such a cool Am star. The finding challenges the theories of diffusion which are widely accepted as the cause of metallicism. The primary component (o Leo A) appears to be deficient in Ca and Sc, as are classical Am stars. Its unusual state may be attributable either to its current state of rapid evolution, or to regular Am-star evolution that is difficult to recognize spectroscopically. A full account of this research appeared in AJ 123, 988-1001, 2002.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The study of detached eclipsing binaries is one of the most powerful ways to investigate the properties of individual stars and stellar systems. We present preliminary masses, radii and effective temperatures for the eclipsing binary WW Aurigae, which is composed of two metallic-lined A-type stars. We also reanalyse the data on HD 23642, an A-type eclipsing binary member of the Pleiades open cluster with a metallic-lined component, and determine its distance to be $139 \pm 4$ pc. This is in agreement with the traditional Pleiades distance, but in disagreement with distance to the Pleiades, and to HD 23642 itself, derived from Hipparcos trigonometrical parallaxes.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The spectroscopic binary observing program of the Mark III Optical Interferometer has produced four published orbits and 22 preliminary orbits. The mean (formal) precision is 0.3% for measurements of sin i and 0.7% for measurements of the semimajor axis a. We list the stars for which we have obtained orbits or preliminary orbits and describe our data and uncertainty analysis techniques.