Related papers: OB Associations
The formation and evolution of young star clusters and OB associations is fundamental to our understanding of the star formation process, the conditions faced by young binary and planetary systems, and the formation of long-lived open and…
We are using HST GO programs 10205, 10602, and 10898 to test the stellar upper mass limit in the solar vicinity by attempting to detect optical close companions, thus lowering the calculated evolutionary masses. We have observed with…
Hipparcos astrometric binaries were observed with the NICI adaptive optics system at Gemini-S, completing the work of Paper I (Tokovinin et al. 2012). Among the 65 F, G, K dwarfs within 67pc of the Sun studied here, we resolve 18 new…
We present an outline of a new reduction of the Hipparcos astrometric data, the justifications of which are described in the accompanying paper. The emphasis is on those aspects of the data analysis that are fundamentally different from the…
We present continued results from a wide-field, ~150 deg^2, optical photometric and spectroscopic survey of the northern part of the ~5 Myr-old Upper Scorpius OB Association. Photometry and spectral types were used to derive effective…
Stars which pass close to the Sun can perturb the Oort cloud, injecting comets into the inner solar system where they may collide with the Earth. Using van Leeuwen's re-reduction of the Hipparcos data complemented by the original Hipparcos…
We present the results of a survey for stellar and substellar companions to 82 young stars in the nearby OB association Upper Scorpius. This survey used nonredundant aperture-mask interferometry to achieve typical contrast limits of…
Walraven photometry of established and probable members of the Orion OB1 association is presented. Effective temperature, surface gravity, luminosity and mass are derived for all stars, using atmosphere models by Kurucz (1979). Absolute…
The first Gaia Data Release presents an opportunity to characterise the low-mass population of OB associations, providing larger statistical samples and better constraints on the formation and evolution of clusters and associations. Using…
We calculated the median parallaxes for 47 OB associations including at least 10 stars with known Gaia DR2 parallaxes. A comparison between trigonometric and photometric parallaxes of OB associations reveals a zero-point offset of…
Statistics of low-mass pre-main sequence binaries in the Orion OB1 association with separations ranging from 0.6" to 20" (220 to 7400 au at 370 pc) are studied using images from the VISTA Orion mini-survey and astrometry from Gaia. The…
Cygnus OB2 is the most massive association within 2kpc from the Sun, hosting hundreds of massive stars, thousands of young low mass members, and some sights of active star formation in the surrounding cloud. Recently, 10 photoevaporating…
We present the results of an aperture masking interferometry survey for substellar companions around 67 members of the young (~8-200Myr) nearby (~5-86pc) AB Doradus, Beta Pictoris, Hercules-Lyra, TW Hya, and Tucana-Horologium stellar…
Lac OB1 is a nearby OB association in its final stage of star formation. While the member stars suggest an expansion time scale of tens of Myr, the latest star formation episode, as manifested by the existence of massive and pre-main…
The low-mass members of OB associations, expected to be a major component of their total population, are in most cases poorly studied because of the difficulty of selecting these faint stars in crowded sky regions. Our knowledge of many OB…
We present results on parallaxes, magnitudes and proper motions for 17 optically identified massive X-ray binaries (MXRB) which were observed during the Hipparcos astrometry mission. This sample includes the sources detected in the…
The Hipparcos mission has made it possible to constrain the positions of nearby field stars in the colour-magnitude diagram with very high accuracy. These positions can be compared with the predictions of stellar evolutionary calculations…
Orbiting low frequency antennas for radio astronomy (OLFAR) that capture cosmic signals in the frequency range below 30MHz could provide valuable insights on our Universe. These wireless swarms of satellites form a connectivity graph that…
The OB associations, which are fossil star formation regions, retain the end-products of the star formation process in an open, unobscured environment. Observations of the low mass stars in OB associations provide a far clearer picture of…
Young Stellar Objects (YSO) are newly formed stars from molecular clouds. They stay close to where they were born and serve as good tracers to study gas and star formation. During cloud evolution, young massive stars can disrupt the…