Related papers: Gaia reference frame amid quasar variability and p…
Gaia will provide parallaxes and proper motions with accuracy ranging from 10 to 1000 microarcsecond on up to one billion stars. Most of these will be disk stars: for an unreddened K giant at 6 kpc, it will measure the distance accurate to…
The Kepler mission has been fantastic for asteroseismology of solar-type stars, but the targets are typically quite distant. As a consequence, the reliability of asteroseismic modeling has been limited by the precision of additional…
Gaia is an all sky, high precision astrometric and photometric satellite of the European Space Agency (ESA) due for launch in 2010-2011. Its primary mission is to study the composition, formation and evolution of our Galaxy. Gaia will…
An analysis of the source position differences between VLBI-based ICRF and $Gaia$-CRF catalogues is a key step in assessing their systematic errors and determining their mutual orientation. One of the main factors that limits the accuracy…
Gaia mission will offer an exceptional opportunity to perform variability studies. The data homogeneity, its optimised photometric systems, composed of 11 medium and 4-5 broad bands, the high photometric precision in G band of one milli-mag…
It is commonly accepted that quasar redshifts have a cosmological character and that most of the quasars are at Gigaparsec distances. However, there are some cases where several quasars with completely different redshifts and a nearby…
Our location in the Milky Way provides an exceptional opportunity to gain insight on the galactic evolution processes, and complement the information inferred from observations of external galaxies. Since the Milky Way is a barred galaxy,…
Observational data from the ESA astrometric mission Gaia determining the positions of celestial objects within an accuracy of few microarcseconds will be soon fully available. Other satellite-based space missions are currently planned to…
Recent modern space missions deliver invaluable information about origin of our universe, physical processes in the vicinity of black holes and other exotic astrophysical objects, stellar dynamics of our galaxy, etc. On the other hand,…
We examine the relationship between source position stability and astrophysical properties of radio-loud quasars making up the International Celestial Reference Frame. Understanding this relationship is important for improving quasar…
A sample of $60,410$ bona fide optical quasars with astrometric proper motions in Gaia EDR3 and spectroscopic redshifts above 0.5 in an oval 8400 square degree area of the sky is constructed. Using orthogonal Zernike functions of polar…
The motion of the barycenter of the Solar System (SSB), the origin of the International Celestial Reference System, causes a directional displacement known as secular aberration. The secular aberration drift caused by the galactocentric…
Context. Asymptotic Giant Branch stars are characterised by complex stellar surface dynamics that affect the measurements and amplify the uncertainties on stellar parameters. The resulting motion of the stellar photo-center could have…
High-precision astrometric and radial-velocity observations require accurate modelling of stellar motions in order to extrapolate measurements over long time intervals, and to detect deviations from uniform motion caused for example by…
The centrifugial acceleration of the Solar system, resulting from the gravitational attraction of the Galaxy centre, causes a phenomenon known as 'secular aberrration drift'. This acceleration of the Solar system barycentre has been ignored…
Combined studies of variable stars and stellar clusters open great horizons, and they allow us to improve our understanding of stellar cluster formation and stellar evolution. In that prospect, the Gaia mission will provide astrometric,…
Usually, the determination of radial velocities of stars relies on the shift of spectral lines by the Doppler effect. Russel & Atkinson (1931) and Oort (1932) already noted that due to the large proper motion and parallax of the white dwarf…
Angular redshift fluctuations (ARF) are a new cosmological observable, recently proposed in the literature. It measures the 2D angular deviations of the average redshift of a given matter tracer under an input redshift shell. Since it…
The masses of stars and planets can be measured dynamically in binary systems. For an unresolved binary, time series astrometry yields some orbital parameters, but it cannot provide the component masses, because we observe only the motion…
A tool for representation of the one-dimensional astrometric signal of Gaia is described and investigated in terms of fit discrepancy and astrometric performance with respect to number of parameters required. The proposed basis function is…