Related papers: Orbital Solution & Fundamental Parameters of sigma…

High-mass binary stars are known to show an unexplained discrepancy between the dynamical masses of the individual components and those predicted by models. In this work, we study Sigma Scorpii, a double-lined spectroscopic binary system…

The triple system HD158926 (lambda Sco) has been observed interferometrically with the Sydney University Stellar Interferometer and the elements of the wide orbit have been determined. These are significantly more accurate than the previous…

The bright southern binary star beta Centauri (HR 5267) has been observed with the Sydney University Stellar Interferometer (SUSI) and spectroscopically with the ESO CAT and Swiss Euler telescopes at La Silla. The interferometric…

Although delta Scorpii is a bright and well-studied star, the details of its multiplicity have remained unclear. Here we present the first diffraction-limited image of this 0.12 arcsec binary star, made using optical interferometry, and…

The first complete orbital solution for the double-lined spectroscopic binary system \gamma^2 Velorum, obtained from measurements with the Sydney University Stellar Interferometer (SUSI), is presented. This system contains the closest…

We present the first double-lined orbital solution for the close binary in the GW Ori triple system. Using 12 epochs of infrared spectroscopy, we detected the lines of both stars in the inner pair, previously known as single-lined only. Our…

The first two of a total of six nano-satellites that will constitute the BRITE-Constellation space photometry mission have recently been launched successfully. In preparation for this project, we carried out time-resolved colour photometry…

The sigma Ori cluster is an unbound aggregate of a few hundred young, low-mass stars centered on the multiple system sigma Ori. This cluster is of great interest because it is at an age when roughly half of the stars have lost their…

The binary star delta Sco (HD143275) underwent remarkable brightening in the visible in 2000, and continues to be irregularly variable. The system was observed with the Sydney University Stellar Interferometer (SUSI) in 1999, 2000, 2001,…

We present the results of a long term orbit monitoring program, using sparse aperture masking observations taken with NIRC2 on the Keck-II telescope, of seven G to M-type members of the Upper Scorpius subgroup of the Sco-Cen OB association.…

The results of speckle interferometric observations at the 4.1 m Southern Astrophysical Research Telescope (SOAR) in 2018 are given, totaling 3097 measurements of 2427 resolved pairs with separations from 11 mas to 5.9" (median 0.15",…

We present the first detection of the mass donor star in the prototype X-ray binary Scorpius X-1. Phase resolved spectroscopy revealed narrow emission lines components from the irradiated secondary star. Radial velocity fits to the Bowen…

We present interferometric observations of the sigma Orionis triple system using the CHARA Array, NPOI, and VLTI. Using these measurements, we spatially resolve the orbit of the close spectroscopic binary (Aa,Ab) for the first time and…

We observed stars with variable radial velocities to determine their spectroscopic orbits. Velocities of 132 targets taken over a time span reaching 30 years are presented. They were measured with the correlation radial velocity…

We report spectroscopic observations of the nearby, 19.5 yr binary system Gls 67 AB spanning more than 35 yr. We carry out a global orbital solution combining our radial velocity measurements with others from the literature going back more…

Binary stars provide a valuable test of stellar structure and evolution, because the masses of the individual stellar components can be derived with high accuracy and in a model-independent way. In this work, we study Spica, an eccentric…

We present the discovery of a substellar companion on a wide orbit around the ~2.5 Msun star HIP 78530, which is a member of the 5 Myr-old Upper Scorpius association. We have obtained follow-up imaging over two years and show that the…

We present 1066 speckle measurements of M dwarf multiples observed over 2021-2024, all taken with HRCam on the Southern Astrophysical Research 4.1 m telescope. Among these, 900 observations resolve companions in 212 pairs, with separations…

Preliminary results on the ongoing spectroscopic study of the six brightest Orion Trapezium stars is presented here. The main purpose of this work is to better understand the multiplicity and stability of each of these subsystems and the…

We describe the results of the world-wide observing campaign of the highly eccentric Be binary system delta Scorpii 2011 periastron passage which involved professional and amateur astronomers. Our spectroscopic observations provided a…