Search Publications
The Tycho-Gaia astrometric solution . How to get 2.5 million parallaxes with less than one year of Gaia data
Michalik, Daniel; Lindegren, Lennart; Hobbs, David
Context. The first release of astrometric data from Gaia will contain the mean stellar positions and magnitudes from the first year of observations, and proper motions from the combination of Gaia data with Hipparcos prior information (HTPM).
Aims: We study the potential of using the positions from the Tycho-2 Catalogue as additional informat…
Gaia FGK benchmark stars: Effective temperatures and surface gravities
Gustafsson, B.; Soubiran, C.; Heiter, U. +3 more
Context. In the era of large Galactic stellar surveys, carefully calibrating and validating the data sets has become an important and integral part of the data analysis. Moreover, new generations of stellar atmosphere models and spectral line formation computations need to be subjected to benchmark tests to assess any progress in predicting stella…
Gaia FGK benchmark stars: abundances of α and iron-peak elements
Gilmore, G.; Montes, D.; Recio-Blanco, A. +26 more
Context. In the current era of large spectroscopic surveys of the Milky Way, reference stars for calibrating astrophysical parameters and chemical abundances are of paramount importance.
Aims: We determine elemental abundances of Mg, Si, Ca, Sc, Ti, V, Cr, Mn, Co, and Ni for our predefined set of Gaia FGK benchmark stars.
Methods: By ana…
Detecting stars, galaxies, and asteroids with Gaia
de Bruijne, J. H. J.; Hestroffer, D.; Krone-Martins, A. +3 more
Context. Gaia is Europe's space astrometry mission, aiming to make a three-dimensional map of 1000 million stars in our Milky Way to unravel its kinematical, dynamical, and chemical structure and evolution.
Aims: We present a study of Gaia's detection capability of objects, in particular non-saturated stars, double stars, unresolved external …
Benchmark stars for Gaia Fundamental properties of the Population II star HD 140283 from interferometric, spectroscopic, and photometric data
Morel, P.; Berio, P.; Meilland, A. +18 more
Metal-poor halo stars are important astrophysical laboratories that allow us to unravel details about many aspects of astrophysics, including the chemical conditions at the formation of our Galaxy, understanding the processes of diffusion in stellar interiors, and determining precise effective temperatures and calibration of colour-effective tempe…
Gaia astrometry for stars with too few observations. A Bayesian approach
Michalik, Daniel; Lindegren, Lennart; Hobbs, David +1 more
Context. The astrometric solution for Gaia aims to determine at least five parameters for each star, representing its position, parallax, and proper motion, together with appropriate estimates of their uncertainties and correlations. This requires at least five distinct observations per star. In the early data reductions the number of observations…
A study of purely astrometric selection of extragalactic point sources with Gaia
Fynbo, J. P. U.; Heintz, K. E.; Høg, E.
Context. Selection of extragalactic point sources, e.g., quasi-stellar objects (QSOs), is often hampered by significant selection effects causing existing samples to have rather complex selection functions.
Aims: We explore whether a purely astrometric selection of extragalactic point sources, e.g., QSOs, is feasible with the ongoing Gaia mis…
The astrometric Gaia-FUN-SSO observation campaign of 99942 Apophis
Sakamoto, T.; Colas, F.; Bikmaev, I. +71 more
Aims: Astrometric observations performed by the Gaia Follow-Up Network for Solar System Objects (Gaia-FUN-SSO) play a key role in ensuring that moving objects first detected by ESA's Gaia mission remain recoverable after their discovery. An observation campaign on the potentially hazardous asteroid (99 942) Apophis was conducted during the as…
Exploration of quasars with the Gaia mission
Wambsganss, Joachim; Proft, Svea
We analyze the opportunities in and limits to investigating quasars with the Gaia satellite by studying Gaia's low- and high-resolution quasar spectra, with consideration of their signal-to-noise ratios. Furthermore, we explore bright quasars from the Sloan Digital Sky Survey with broad emission lines (BELs) redshifted into the spectral range of G…
Detection of Yarkovsky acceleration in the context of precovery observations and the future Gaia catalogue
Desmars, J.
Context. The Yarkovsky effect is a weak non-gravitational force leading to a small variation of the semi-major axis of an asteroid. Using radar measurements and astrometric observations, it is possible to measure a drift in semi-major axis through orbit determination.
Aims: This paper aims to detect a reliable drift in semi-major axis of near…