Related papers: On the accuracy of close stellar approaches determ…

Gaia measures the five astrometric parameters for stars in the Milky Way, but only four of them (positions and proper motion, but not parallax) are well measured beyond a few kpc from the Sun. Modern spectroscopic surveys such as APOGEE…

Asteroseismology provides fundamental properties (mass, radius and effective temperature) of solar-like oscillating stars using so-called scaling relations. These properties allow the computation of the asteroseismic distance of stars. We…

We simulate the astrometric observations of stars moving close to the black hole in the Galactic Center. We show, that for orbits =<1000 AU and position measurements with the accuracy of the Keck Interferometer, the periastron motion of…

We argue that tracing star formation histories with ESA's space mission GAIA using main sequence turn-off (MSTO) point dating will mainly be effective in cases of mild interstellar extinction (E(B-V)<0.5). For higher reddenings the MSTO…

From the XHIP catalogue, we have selected 1872 F-G-K stars with relative parallax measurement errors <20% and absolute values of their space velocities relative to the Sun <15 km/s. For all these stars, we have constructed their Galactic…

Gaia Data Release 1 (Gaia DR1) contains astrometric results for more than 1 billion stars brighter than magnitude 20.7 based on observations collected by the Gaia satellite during the first 14 months of its operational phase. We give a…

It is challenging to reliably identify stars that were born together outside of actively star-forming regions and bound stellar systems. However, co-natal stars should be present throughout the Galaxy, and their demographics can shed light…

We present the results of a large-scale proper motion study of the central ~36'x16' of the Milky Way, based on our high angular resolution GALACTICNUCLEUS survey (epoch 2015) combined with the HST Paschen-alpha survey (epoch 2008). Our…

Multi-epoch radio-interferometric observations of young stellar objects can be used to measure their displacement over the celestial sphere with a level of accuracy that currently cannot be attained at any other wavelength. In particular,…

Despite their relatively high intrinsic brightness and the fact that they are more numerous than younger OB stars and kinematically colder than older red giants, A-type stars have rarely been used as Galactic tracers. They may, in fact, be…

In this work we improve a previously published method to calculate in a reliable way the radius of an open cluster. The method is based on the behaviour of stars in the proper motion space as the sampling changes in the position space. Here…

A most desirable feature of a standard candle to estimate astronomical distances is robustness against changes in metallicity and age. It is argued that the radii of main sequence stars with spectral types from solar to A0 show predictable…

Two motions in the galactic plane have been detected and characterized, based on the determination of a common systematic component in Hipparcos catalogue proper motions. The procedure is based only on positions, proper motions and…

Trigonometric parallaxes measured with ground-based telescopes of the RECONS consortium as part of the CTIOPI program are used to search for stars that have either had an encounter with the solar system in the past or will have such an…

Taking advantage of the Gaia DR1, we combined TGAS parallaxes with the Tycho-2 and APASS photometry to calculate the star formation history (SFH) of the solar neighbourhood within 250 pc using the colour-magnitude diagram fitting technique.…

We have studied stellar candidates for close (within 1 pc) encounters with the Solar system. For all of the stars under consideration the kinematic characteristics have been taken from the Gaia EDR3 catalogue. The parameters of the…

The accuracy of the link of the proper motion system of astrometric satellite missions like AMEX and GAIA is discussed. Monte-Carlo methods were used to simulate catalogues of positions and proper motions of quasars and galaxies to test the…

We present a proper motion survey over about 200 square degrees towards the NGP, based on the material used for the construction of the GSC-II, that we are using to study the vertical structure and kinematics of the Galaxy. In particular,…

Aims. The aim is to derive accurate stellar distances and extinctions for young stars of our survey in the Galactic anticenter direction using the Str\"omgren photometric system. This will allow a detailed mapping of the stellar density and…

We present a test for spin-orbit alignment for the host stars of 25 candidate planetary systems detected by the {\it Kepler} spacecraft. The inclination angle of each star's rotation axis was estimated from its rotation period, rotational…