Related papers: Undetected Binary Stars Cause an Observed Mass Dep…
Observations indicate that in young stellar clusters the binary fraction for massive stars is higher than for solar mass stars. For the Orion Nebula Cluster (ONC) there is a binary frequency of ~ 50% for solar-mass stars compared to 70-100%…
Populations of massive stars are directly reflective of the physics of stellar evolution. Counting subtypes of massive stars and ratios of massive stars in different evolutionary states have been used ubiquitously as diagnostics of age and…
(Abridged) Our aim is to identify analogues of gas giant planets, as companions at wide separations of very young stars. To identify these objects, we cross correlated the Visible and Infrared Survey Telescope for Astronomy (VISTA)…
We have carried out a Galaxy Evolution Explorer (GALEX) Cycle 1 guest investigator program covering 56 square degrees near the Taurus T association and 12 square degrees along the northern edge of the Upper Scorpius OB association. We…
Infrared spectroscopy provides a powerful diagnostic for probing the mineralogical properties of dust grains in the terrestrial planet-forming regions of protoplanetary disks. The Upper Scorpius association offers an excellent laboratory…
We present results of age determination based on the standard procedure of isochrone fitting for about 600 star clusters younger than about 1.2 Gyr from the central parts of the LMC. Comparison of age distributions of star clusters from the…
Mass, radius, and age are three of the most fundamental parameters for celestial objects, enabling studies of the evolution and internal physics of stars, brown dwarfs, and planets. Brown dwarfs are hydrogen-rich objects that are unable to…
The Young Suns Exoplanet Survey (YSES) consists of a homogeneous sample of 70 young, solar-mass stars located in the Lower Centaurus-Crux subgroup of the Scorpius-Centaurus association with an average age of $15\pm3\,$Myr. We report the…
Cygnus OB2 provides a unique insight into the high-mass stellar content in one of the largest groups of young massive stars in our Galaxy. Although several studies of its massive population have been carried out over the last decades, an…
Giant planets are usually thought to form within a few tens of AU of their host stars, and hence it came as a surprise when we found what appeared to be a planetary mass (~0.008 Msun) companion around the 5 Myr-old solar mass star 1RXS…
We present results from a large, high-spatial-resolution near-infrared imaging search for stellar and sub-stellar companions in the Taurus-Auriga star-forming region. The sample covers 64 stars with masses between those of the most massive…
We investigate the stellar populations in the star forming ring of the luminous infrared galaxy NGC 7469. We use Hubble Space Telescope multi-wavelength (UV through NIR) imaging complemented with new K-band ground-based long-slit…
We derive a new age for the Gamma^2 Velorum binary by comparing recent observations to our set of binary models. We find that it is very unlikely the stars have not interacted, which implies that previous estimates of the age from…
The nearest region of massive star formation - the Scorpius-Centaurus OB2 association (Sco-Cen) - is a local laboratory ideally suited to the study of a wide range of astrophysical phenomena. Precision astrometry from the Gaia mission has…
The 32 Orionis group was discovered almost a decade ago and despite the fact that it represents the first northern, young (age ~ 25 Myr) stellar aggregate within 100 pc of the Sun ($d \simeq 93$ pc), a comprehensive survey for members and…
The Orion complex is arguably the most studied star-forming region in the Galaxy. While stars are still being born in the Orion nebula, the oldest part was believed to be no more than 13 Myr old. In order to study the full hierarchy of star…
We analyze the stellar populations of the Canis Major stellar over-density, using quantitative color-magnitude diagram (CMD) fitting techniques. The analysis is based on photometry obtained with the Wide Field Imager at the 2.2m telescope…
The Upper-Scorpius association (5-11 Myr) contains a unique population of low-mass (M<30 MJup) brown-dwarfs. The detailed relative characterization of their physical properties (mass, radius, temperature, composition, ongoing accretion)…
Rotation periods and projected equatorial velocities of pre-main-sequence (PMS) stars in star forming regions can be combined to give projected stellar radii. Assuming random axial orientation, a Monte-Carlo model is used to illustrate that…
We use the Binary Population and Spectral Synthesis (BPASS) models to test the recent suggestion that red supergiants can provide an accurate age estimate of a co-eval stellar population that is unaffected by interacting binary stars. Ages…