Showing papers by "J. H. J. de Bruijne published in 2001"
TL;DR: In this article, the authors used milli-arcsecond accuracy astrometry (proper motions and parallaxes) from Hipparcos and from radio observations to retrace the orbits of 56 runaway stars and nine compact objects with distances less than 700 pc, to identify the parent stellar group.
Abstract: We use milli-arcsecond accuracy astrometry (proper motions and parallaxes) from Hipparcos and from radio observations to retrace the orbits of 56 runaway stars and nine compact objects with distances less than 700 pc, to identify the parent stellar group. It is possible to deduce the specific formation scenario with near certainty for two cases. (i) We find that the runaway star ζ Ophiuchi and the pulsar PSR J1932+1059 originated about 1 Myr ago in a supernova explosion in a binary in the Upper Scorpius subgroup of the Sco OB2 association. The pulsar received a kick velocity of ∼ 350 km s-1 in this event, which dissociated the binary, and gave ζ Oph its large space velocity. (ii) Blaauw & Morgan and Gies & Bolton already postulated a common origin for the runaway-pair AE Aur and μ Col, possibly involving the massive highly-eccentric binary ι Ori, based on their equal and opposite velocities. We demonstrate that these three objects indeed occupied a very small volume ∼ 2.5 Myr ago, and show that they were ejected from the nascent Trapezium cluster. We identify the parent group for two more pulsars: both likely originate in the ∼ 50 Myr old association Per OB3, which contains the open cluster α Persei. At least 21 of the 56 runaway stars in our sample can be linked to the nearby associations and young open clusters. These include the classical runaways 53 Arietis (Ori OB1), ξ Persei (Per OB2), and λ Cephei (Cep OB3), and fifteen new identifications, amongst which a pair of stars running away in opposite directions from the region containing the λ Ori cluster. Other currently nearby runaways and pulsars originated beyond 700 pc, where our knowledge of the parent groups is very incomplete.
363 citations
TL;DR: In this paper, the Hipparcos proper motions are used to derive 3 times more precise distance estimates, by assuming that all members share the same space motion, and the new parallaxes provide a uniquely sharp view of the three-dimensional structure of the Hyades.
Abstract: Hipparcos parallaxes x distances to individual stars in the Hyades cluster with an accuracy of 6p er- cent. We use the Hipparcos proper motions, which have a larger relative precision than the trigonometric paral- laxes, to derive 3 times more precise distance estimates, by assuming that all members share the same space motion. An investigation of the available kinematic data conrms that the Hyades velocity eld does not contain signicant structure in the form of rotation and/or shear, but is fully consistent with a common space motion plus a (one-dimensional) internal velocity dispersion of 0.30 km s 1 . The improved parallaxes as a set are statistically consistent with the Hipparcos parallaxes. The maximum expected systematic error in the proper motion-based parallaxes for stars in the outer regions of the cluster (i.e., beyond 2 tidal radii 20 pc) is < 0.30 mas. The new parallaxes conrm that the Hipparcos measurements are correlated on small angular scales, consistent with the limits specied in the Hipparcos Catalogue, though with signicantly smaller \amplitudes" than claimed by Narayanan & Gould. We use the Tycho{2 long time-baseline astrometric catalogue to derive a set of independent proper motion-based parallaxes for the Hipparcos members. The new parallaxes provide a uniquely sharp view of the three-dimensional structure of the Hyades. The colour-absolute magnitude diagram of the cluster based on the new parallaxes shows a well-dened main sequence with two \gaps"/\turn-os". These features provide the rst direct observational support of Bohm{Vitense's prediction that (the onset of) surface convection in stars signicantly aects their (B V ) colours. We present and discuss the theoretical Hertzsprung{Russell diagram (log L versus log Te) for an objectively dened set of 88 high-delity members of the cluster as well as the Scuti star 2 Tau, the giants 1 , 1 , ,a nd Tau, and the white dwarfs V471 Tau and HD 27483 (all of which are also members). The precision with which the new parallaxes place individual Hyades in the Hertzsprung{Russell diagram is limited by (systematic) uncertainties related to the transformations from observed colours and abso- lute magnitudes to eective temperatures and luminosities. The new parallaxes provide stringent constraints on the calibration of such transformations when combined with detailed theoretical stellar evolutionary modelling, tailored to the chemical composition and age of the Hyades, over the large stellar mass range of the cluster probed by Hipparcos.
207 citations
TL;DR: In this paper, the Hipparcos proper motion of the high-mass X-ray binary HD153919/4U1700-37 was analyzed and it was shown that the system's kinematical age is about 2 +/- 0.5 million years.
Abstract: Based on its Hipparcos proper motion, we propose that the high-mass X-ray binary HD153919/4U1700-37 originates in the OB association Sco OB1. At a distance of 1.9 kpc the space velocity of 4U1700-37 with respect to Sco OB1 is 75 km/s. This runaway velocity indicates that the progenitor of the compact X-ray source lost about 7 Msun during the (assumed symmetric) supernova explosion. The system's kinematical age is about 2 +/- 0.5 million years which marks the date of the supernova explosion forming the compact object. The present age of Sco OB1 is 30 Msun. With these parameters the evolution of the binary system can be constrained.
65 citations