Search Publications
On the age of the β Pictoris moving group
Mamajek, Eric E.; Bell, Cameron P. M.
Binks & Jeffries and Malo et al. have recently reported Li depletion boundary (LDB) ages for the β Pictoris moving group (BPMG) which are twice as old as the oft-cited kinematic age of ∼12 Myr. In this study, we present (1) a new evaluation of the internal kinematics of the BPMG using the revised Hipparcos astrometry and best available publish…
New distances to RAVE stars
Gilmore, G.; Watson, F.; Steinmetz, M. +16 more
Probability density functions (pdfs) are determined from new stellar parameters for the distance moduli of stars for which the RAdial Velocity Experiment (RAVE) has obtained spectra with S/N ≥ 10. Single-Gaussian fits to the pdf in distance modulus suffice for roughly half the stars, with most of the other half having satisfactory two-Gaussian rep…
Two estimates of the distance to the Galactic Centre
Francis, Charles; Anderson, Erik
We use recently updated globular cluster distances to estimate the distance to the Galactic Centre, finding 7.4 ± 0.2|stat ± 0.2|sys kpc from symmetry considerations, including a trough at the Galactic Centre and peaks denoting the position of the bar. We recalibrate the red clump magnitude from Hipparcos stars, finding a ske…
Planet X revamped after the discovery of the Sedna-like object 2012 VP113?
Iorio, L.
The recent discovery of the Sedna-like dwarf planet 2012 VP113 by Trujillo and Sheppard has revamped the old-fashioned hypothesis that a still unseen trans-Plutonian object of planetary size, variously dubbed over the years as Planet X, Tyche and Telisto, might lurk in the distant peripheries of the Solar system. This time, the presence…
The local standard of rest from data on young objects with account for the Galactic spiral density wave
Bobylev, V. V.; Bajkova, A. T.
To estimate the peculiar velocity of the Sun with respect to the local standard of rest (LSR), we used young objects in the Solar neighbourhood with distance measurement errors within 10-15 per cent. These objects were the nearest Hipparcos stars of spectral classes O-B2.5, masers with trigonometric parallaxes measured by means of very long baseli…
The Lutz-Kelker paradox.
Francis, C.
The Lutz-Kelker correction is intended to give an unbiased estimate for stellar parallaxes and magnitudes, but it is shown explicitly that it does not. This paradox results from the application of an argument about sample statistics to the treatment of individual stars, and involves the erroneous use of a frequency distribution in the manner of a …
Tracing CNO exposed layers in the Algol-type binary system u Her
Southworth, J.; Pavlovski, K.; Dervişoğlu, A. +1 more
The chemical composition of stellar photospheres in mass-transferring binary systems is a precious diagnostic of the nucleosynthesis processes that occur deep within stars, and preserves information on the components' history. The binary system u Her belongs to a group of hot Algols with both components being B stars. We have isolated the individu…
Application of the Baade-Wesselink method to a pulsating cluster Herbig Ae star: H254 in IC348
Ripepi, V.; Molinaro, R.; Palla, F. +6 more
In this paper we present new photometric and radial velocity data for the PMS δ Sct star H254, member of the young cluster IC 348. Photometric V, RC, IC light curves were obtained at the Loiano and Asiago telescopes. The radial velocity data were acquired by means of the SARG@Telescopio Nazionale Galileo spectrograph. High-re…
High proper motion X-ray binaries from the Yale Southern Proper Motion Survey
Maccarone, Thomas J.; Casetti-Dinescu, Dana I.; Girard, Terrence M.
We discuss the results of cross-correlating catalogues of bright X-ray binaries with the Yale Southern Proper Motion Catalog (version 4.0). Several objects already known to have large proper motions from Hipparcos are recovered. Two additional objects are found which show substantial proper motions, both of which are unusual in their X-ray propert…
V745 Cassiopean interacting young massive binary in a multiple-star system
Ibanoglu, C.; Çakırlı, Ö.; Sipahi, E.
We present spectroscopic observations of the massive early-type system V745 Cas, embedded in a multiple-star system. The brightest star of the system is the eclipsing binary V745 Cas with an orbital period of 1.41 d. The radial velocities of both components and light curves obtained by INTEGRAL and Hipparcos missions were analysed. The components …