Related papers: OB associations: from stellar to galactic scales
OB associations are unbound groups of young stars made prominent by their bright OB members, and have long been thought to be the expanded remnants of dense star clusters. They have been important in astrophysics for over a century thanks…
OB associations are low-density groups of young stars that are dispersing from their birth environment into the Galactic field. They are important for understanding the star formation process, early stellar evolution, the properties and…
We present the first results of a comprehensive census of the stellar content of the nearby OB associations based on Hipparcos positions, proper motions and parallaxes for 12842 candidate member stars distributed over 21 fields on the sky.…
In this review I discuss different theories of the formation of OB associations in the Milky Way, and provide the observational evidences in support of them. In fact, the second release of Gaia astrometric data (April 2018) is…
Since the previous (1990) edition of this meeting enormous progress in the field of OB associations has been made. Data from X-ray satellites have greatly advanced the study of the low-mass stellar content of associations, while astrometric…
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…
Stars like company. They are mostly formed in clusters and their lives are often altered by the presence of one or more companions. Interaction processes between components may lead to complex outcomes like Algols, blue stragglers,…
OB associations are primordial tracers of star formation and Galactic structure. Originally defined about 80 years ago, their historical membership lists have been superseded thanks to the precise astrometry from ESA's \textit{Gaia}'s…
If we want to understand the evolution from star clusters to the Galactic field star population, the Solar neighbourhood is an ideal place to start. It contains objects from dense, very young clusters to old and almost dissolved moving…
We review the current knowledge of the population of `older' stars in the Orion OB1 association, specifically those in subgroups 1a and 1b. We briefly outline the history of the subject and then continue with a summary of the present state…
Open clusters and associations are groups of young stars, respectively bound and unbound, that share the same origin and disperse over time into the galactic field. As such, their formation and evolution are the key to understand the origin…
Historically, it has often been asserted that most stars form in compact clusters. In this scenario, present-day gravitationally-unbound OB associations are the result of the expansion of initially gravitationally-bound star clusters.…
OB associations play an important role in Galactic evolution, though their origins and dynamics remain poorly studied, with only a small number of systems analysed in detail. In this paper we revisit the existence and membership of the…
CONTEXT. The GOSSS spectral classifications and Gaia data have significantly improved our ability to measure distances and determine memberships of stellar groups with OB stars. AIMS. We have started a program to identify, measure…
The kinematics of low-mass stars in nearby OB associations can provide clues about their origins and evolution. Combining the precise positions, proper motions and parallaxes given in the second Gaia Data Release with radial velocity…
We present 3-dimensional kinematical observations of the massive OB association Cygnus OB2 to identify the mechanisms responsible for disrupting young star clusters. The picture revealed by these observations is of a highly-substructured,…
Nearby associations of stars which are coeval are important benchmark laboratories because they provide robust measurements of stellar ages. The study of such coeval groups makes it possible to better understand star formation by studying…
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…
During the last decade, the understanding of fine features of the structure and evolution of stars has become possible as a result of enormous progress made in the acquisition of high-quality observational and experimental data and of new…
Low-mass stars 0.1 ~< M ~< 1 Msun) in OB associations are key to addressing some of the most fundamental problems in star formation. The low-mass stellar populations of OB associations provide a snapshot of the fossil star-formation record…