相关论文: Wide binaries in the Orion Nebula Cluster
The formation of very wide binaries, such as the alpha Cen system with Proxima (also known as alpha Centauri C) separated from alpha Centauri (which itself is a close binary A/B) by 15000 AU, challenges current theories of star formation,…
We report here on two complementary population synthesis studies which relate directly to the formation and evolution of neutron star binaries in globular clusters. In the first, we compute the probability of retaining neutron stars in…
We analyze a ~70 ksec Chandra ACIS-I exposure of the globular cluster Omega Centauri (NGC 5139). The ~17 amin x 17 amin field of view fully encompasses three core radii and almost twice the half-mass radius. We detect 180 sources to a…
Though about 80 pulsar binaries have been detected in globular clusters so far, no pulsar has been found in a triple system in which all three objects are of comparable mass. Here we present predictions for the abundance of such triple…
The distance to the Orion Nebula Cluster (ONC) is estimated using the rotational properties of its low-mass pre main-sequence (PMS) stars. Rotation periods, projected equatorial velocities and distance-dependent radius estimates are used to…
Binary fraction and orbital characteristics provide indications on the conditions of star formation, as they shed light on the environment they were born in. Multiple systems are more common in low density environments rather than in higher…
Approximately 10 per cent of star clusters are found in pairs, known as binary clusters. We propose a mechanism for binary cluster formation; we use N-body simulations to show that velocity substructure in a single (even fairly smooth)…
The wide luminosity dispersion seen for stars at a given effective temperature in the H-R diagrams of young clusters and star forming regions is often interpreted as due to significant (~10 Myr) spreads in stellar contraction age. In the…
The formation of stars above about twenty solar masses and their apparently high multiplicity remain heavily debated subjects in astrophysics. We have performed a vast high-resolution radial velocity spectroscopic survey of about 250 O- and…
(abridged) 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…
Aims. We present a study of the distribution of stellar ages in the Orion Nebula Cluster (ONC) based on accurate HST photometry taken from the HST Treasury Program observations of the ONC utilizing the most recent estimate of the cluster's…
We used deep wide field photometric observations to derive the fraction of binary systems in a sample of five high-latitude Galactic open clusters. By analysing the color distribution of Main Sequence stars we derived the minimum fraction…
We investigate the dynamical formation and evolution of binaries containing neutron stars in dense globular clusters. Our numerical simulations combine a simple Monte Carlo prescription for stellar dynamics, a sophisticated binary…
Observations revealed the presence of multiple stellar populations in globular clusters (GCs) that exhibit wide abundance variations and multiple sequences in Hertzsprung-Russell (HR) diagram. We present a scenario for the formation of…
We present a wide-field (~6'x6') and deep near-infrared (Ks band: 2.14 micro m) circular polarization image in the Orion nebula, where massive stars and many low-mass stars are forming. Our results reveal that a high circular polarization…
(Abridged) We have used optical spectroscopy to investigate the radio- selected active galaxy populations in a sample of 20 nearby Abell clusters. The spectra were used to characterize the galaxies as AGN or galaxies forming stars at rates…
(abridged) Observations of very high speeds among pulsars in the Galactic disk present a puzzle regarding neutron stars in globular clusters. The inferred characteristic speed of single pulsars in the Galaxy is $\sim 5-10$ times as large as…
A number of scenarios for the formation of multiple populations in globular clusters (GCs) predict that second generation (2G) stars form in a compact and dense subsystem embedded in a more extended first-generation (1G) system. If these…
We have conducted a high-resolution imaging study of the Taurus-Auriga star-forming region in order to characterize the primordial outcome of multiple star formation and the extent of the brown dwarf desert. Our survey identified 16 new…
In this first of two companion papers on the Orion Nebula Cluster (ONC), we present our analysis of a 63 Ksec Chandra HRC-I observation that yielded 742 X-ray detections within the 30'x30' field of view. To facilitate our interpretation of…