We present an interpretation of Hipparcos Hp and Walraven V BLUW photometry of the brightest star in the open cluster NGC 2362 (although not necessarily associated with this cluster), HD 57061 (30 CMa, HR 2782, HIP 35415). In this multiple system the central component consist of a visual double star, two O-type stars separated by 0: 00 151, which is also known to be a 154: d 9 period single lin...

Star formation in the Taurus–Auriga (TA) molecular clouds is producing binary-rich aggregates containing at most a few dozen systems within a region spanning one pc without massive stars. This environment is very different to another well-studied starforming event which produced the Orion Nebula cluster (ONC). The ONC contains a few thousand systems within a region of one pc including massive s...

I compare the structures of the bipolar nebulae around the massive binary system η Carinae and around the low mass binary system HD 44179. While η Carinae is on its way to become a supernova, the Red Rectangle is on its way to form a planetary nebula. Despite the two orders of magnitude difference in mass, these two systems show several similarities, both in the properties of the stellar binary...

Various surveys of low-mass binaries in star forming regions have been performed in recent years. They reached opposite conclusions concerning possible binary excesses in some of these associations. I develop a consistent method to reanalyze all these studies, so that I can compare all data consistently, and understand the previous findings. I also report the detection of five new companions to...

We examine the selection effects that determine how the population of inspiraling binary compact objects (BCOs) is reflected by those potentially observed with ground-based interferometers like LIGO. We lay the ground-work for the interpretation of future observations in terms of constraints on the real population and, correspondingly, binary star evolution models. To determine the extra-galact...

We present new optical and infrared (IR) observations of Cir X-1 taken near apastron. Both sets of spectra show asymmetric emission lines. Archival optical observations show that an asymmetric Hα emission line has been in evidence for the past twenty years, although the shape of the line has changed significantly. We present an eccentric (e ∼ 0.7–0.9) low mass binary model, where the system con...

We present an interpretation of Hipparcos Hp and WalravenV BLUW photometry of the brightest star in the open clusterNGC 2362 (although not necessarily associatedwith this cluster), HD 57061 (30τ CMa, HR 2782, HIP 35415). In this multiple system the central component consist of a visual double star, two O-type stars separated by 0. ′′151, which is also known to be a 154. d9 period single lined s...

Binary radio pulsars are superb tools for mapping binary orbits, because of the precision of the pulse timing method (e.g Taylor & Weisberg 1989). To date, all orbital parameters for binary pulsars have been derived from observations of the pulsar alone. We present the rst observations of the radial velocity variations due to the binary motion of a companion to a radio pulsar. Our results demon...

Aims. The present dynamical configuration of planets in binary star systems may not reflect their formation process since the binary orbit may have changed in the past after the planet formation process was completed. An observed binary system may have been part of a former hierarchical triple that became unstable after the planets completed their growth around the primary star. Alternatively, ...

We discovered that the Wolf-Rayet (WR)+OB star binary, WR 104, renowned for its associated “dusty pinwheel nebula” recently spatially resolved with infrared interferometry, exhibits strong quasi-periodic optical variations with a full amplitude of 2.7 mag. Such a large-amplitude, continuous variation has been unprecedented in a WR star. The optical quasi-period (∼241 d) is in almost perfect agr...