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…
From Binaries to Multiples. I. Data on F and G Dwarfs within 67 pc of the Sun
Tokovinin, Andrei
Data on the multiplicity of F- and G-type dwarf stars within 67 pc of the Sun are presented. This distance-limited sample based on the Hipparcos catalog contains 4847 primary stars (targets) with 0.5 < V - IC < 0.8 and is >90% complete. There are 2196 known stellar pairs; some of them belong to 361 hierarchical systems from tri…
The Besançon Galaxy model renewed. I. Constraints on the local star formation history from Tycho data
Luri, X.; Figueras, F.; Haywood, M. +2 more
Context. The understanding of Galaxy evolution can be facilitated by the use of population synthesis models, which allows us to test hypotheses on the star formation history, star evolution, and chemical and dynamical evolution of the Galaxy.
Aims: The new version of the Besançon Galaxy model (BGM) aims to provide a more flexible and powerful…
A VLBI resolution of the Pleiades distance controversy
Stauffer, John R.; Bower, Geoffrey C.; Melis, Carl +2 more
Because of its proximity and its youth, the Pleiades open cluster of stars has been extensively studied and serves as a cornerstone for our understanding of the physical properties of young stars. This role is called into question by the “Pleiades distance controversy,” wherein the cluster distance of 120.2 ± 1.5 parsecs (pc) as measured by the op…
Isochrones for Old (>5 Gyr) Stars and Stellar Populations. I. Models for -2.4 <= [Fe/H] <=+0.6, 0.25 <= Y <= 0.33, and -0.4 <= [α/Fe] <=+0.4
Edvardsson, Bengt; VandenBerg, Don A.; Ferguson, Jason W. +1 more
Canonical grids of stellar evolutionary sequences have been computed for the helium mass-fraction abundances Y = 0.25, 0.29, and 0.33, and for iron abundances that vary from -2.4 to +0.4 (in 0.2 dex increments) when [α/Fe] =+0.4, or for the ranges -2.0 <= [Fe/H] <=+0.6, -1.8 <= [Fe/H] <=+0.6 when [α/Fe] =0.0 and -0.4, respectively. The…
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…
Hubble Space Telescope CALSPEC Flux Standards: Sirius (and Vega)
Bohlin, R. C.
The Space Telescope Imaging Spectrograph (STIS) has measured the flux for Sirius from 0.17 to 1.01 µm on the Hubble Space Telescope (HST) White Dwarf scale. Because of the cool debris disk around Vega, Sirius is commonly recommended as the primary IR flux standard. The measured STIS flux agrees well with predictions of a special Kurucz model…
Wide Cool and Ultracool Companions to Nearby Stars from Pan-STARRS 1
Chambers, Kenneth C.; Magnier, Eugene A.; Wainscoat, Richard J. +18 more
We present the discovery of 57 wide (>5'') separation, low-mass (stellar and substellar) companions to stars in the solar neighborhood identified from Pan-STARRS 1 (PS1) data and the spectral classification of 31 previously known companions. Our companions represent a selective subsample of promising candidates and span a range in spectral type…
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…
Transit Confirmation and Improved Stellar and Planet Parameters for the Super-Earth HD 97658 b and its Host Star
Queloz, D.; Demory, B. -O.; Ehrenreich, D. +15 more
Super-Earths transiting nearby bright stars are key objects that simultaneously allow for accurate measurements of both their mass and radius, providing essential constraints on their internal composition. We present here the confirmation, based on Spitzer transit observations, that the super-Earth HD 97658 b transits its host star. HD 97658 is a …