Search Publications
Kinematics and history of the solar neighbourhood revisited
Binney, James J.; Aumer, Michael
We use proper motions and parallaxes from the new reduction of Hipparcos data and Geneva-Copenhagen radial velocities for a complete sample of ~15000 main-sequence and subgiant stars, and new Padova isochrones to constrain the kinematics and star formation history of the solar neighbourhood. We rederive the solar motion and the structure of the lo…
Kinematics of OB-associations and the new reduction of the Hipparcos data
Dambis, A. K.; Mel'Nik, A. M.
The proper motions of OB-associations computed using the old and new reductions of the Hipparcos data are in good agreement with each other. The Galactic rotation curve derived from an analysis of the line-of-sight velocities and proper motions of OB-associations is almost flat in the 3-kpc neighbourhood of the Sun. The angular rotation velocity a…
Asteroseismic analysis of the roAp star α Circini: 84d of high-precision photometry from the WIRE satellite
Handler, G.; Kurtz, D. W.; Bruntt, H. +8 more
We present a detailed study of the pulsation of αCircini, the brightest of the rapidly oscillating Ap stars. We have obtained 84d of high-precision photometry from four runs with the star tracker on the WIRE satellite. Simultaneously, we collected ground-based Johnson B observations on 16 nights at the South African Astronomical Observatory. In ad…
Hierarchical star formation: stars and stellar clusters in the Gould Belt
Alfaro, E. J.; Cabrera-Caño, J.; Elias, F.
We perform a study of the spatial and kinematical distribution of young open clusters in the solar neighbourhood, discerning between bound clusters and transient stellar condensations within our sample. Then, we discriminate between Gould Belt (GB) and local Galactic disc (LGD) members, using our previous estimate of the structural parameters of b…
Spectroscopic orbits for K giants β Reticuli and ν Octantis: what is causing a low-amplitude radial velocity resonant perturbation in ν Oct?
Pourbaix, D.; Ramm, D. J.; Hearnshaw, J. B. +1 more
New astrometric-spectroscopic orbital solutions for the single-line K-giant binaries β Reticuli (P ~ 5.2yr, e = 0.3346 +/- 0.0004) and ν Octantis (P ~ 2.9yr, e = 0.2358 +/- 0.0003) have been derived based on high-precision spectroscopic radial velocities (RVs) and the Hipparcos astrometry. For the case of ν Oct, the simultaneous solution is partic…
Long-term photometry and periods for 261 nearby pulsating M giants
Kjeldsen, H.; Kiss, L. L.; Bedding, T. R. +3 more
We present the results of a 5.5-yr CCD photometric campaign that monitored 261 bright, southern, semiregular variables (SRVs) with relatively precise Hipparcos parallaxes. The data are supplemented with independent photoelectric observations of 34 of the brightest stars, including 11 that were not part of the CCD survey, and a previously unpublish…
A new determination of the orbit and masses of the Be binary system δ Scorpii
Tuthill, P. G.; Davis, J.; Tango, W. J. +5 more
The binary star δ Sco (HD143275) underwent remarkable brightening in the visible in 2000, and continues to be irregularly variable. The system was observed with the Sydney University Stellar Interferometer (SUSI) in 1999, 2000, 2001, 2006 and 2007. The 1999 observations were consistent with predictions based on the previously published orbital ele…
The radius and other fundamental parameters of the F9V star β Virginis
Stello, D.; Tuthill, P. G.; Lacour, S. +10 more
We have used the Sydney University Stellar Interferometer (SUSI) to measure the angular diameter of the F9V star β Virginis (β Vir). After correcting for limb darkening and combining with the revised Hipparcos parallax, we derive a radius of 1.703 +/- 0.022Rsolar (1.3 per cent). We have also calculated the bolometric flux from published…
Towards multiple-star population synthesis
Eggleton, P. P.
The multiplicities of stars, and some other properties, were collected recently by Eggleton & Tokovinin, for the set of 4559 stars with Hipparcos magnitude brighter than 6.0 (4558 excluding the Sun). In this paper I give a numerical recipe for constructing, by a Monte Carlo technique, a theoretical ensemble of multiple stars that resembles the…
SDSS absolute magnitudes for thin-disc stars based on trigonometric parallaxes
Cabrera-Lavers, A.; Bilir, S.; Yaz, E. +3 more
We present a new luminosity-colour relation based on trigonometric parallaxes for thin-disc main-sequence stars in Sloan Digital Sky Survey (SDSS) photometry. We matched stars from the newly reduced Hipparcos catalogue with the ones taken from Two-Micron All-Sky Survey (2MASS) All-Sky Catalogue of Point Sources, and applied a series of constraints…