In astrophysical applications, derived quantities like distances, absolute magnitudes and velocities are used instead of the observed quantities, such as parallaxes and proper motions. As the observed values are affected by random errors and selection effects, the estimates of the astrophysical quantities can be biased if a correct statistical treatment is not used. This paper presents and disc...

ABSTRACT Gaia DR3 parallaxes are used to calibrate preliminary period–luminosity relations of O-rich Mira variables in the 2MASS J, H, and Ks bands using a probabilistic model accounting for variations parallax zero-point underestimation uncertainties. The derived compared those measured Large Small Magellanic Clouds, Sagittarius dwarf spheroidal galaxy, globular cluster members, subset Milky W...

The tension between the Hipparcos parallax of the Pleiades and other independent distance estimates continues even after the new reduction of the Hipparcos astrometric data and the development of a new geometric distance measurement for the cluster. A short Pleiades distance from the Hipparcos parallax predicts a number of stars in the solar neighborhood that are sub-luminous at a given photosp...

We have used the newly available Hipparcos parallaxes to study the evolutionary status of a number of high-lithium, high-activity late-type dwarfs found in X-ray based surveys, i.e. the Einstein Extended Medium Sensitivity Survey and the Einstein Slew Survey. The sample stars are placed on evolutionary tracks thus estimating their age.