Stellar multiplicity is among the oldest and richest problems in astrophysics. Binary stars are
a cornerstone of stellar mass and radius measurements that underpin modern stellar …

We report the discovery of the classical Cepheid OGLE-GD-CEP-1884 (= GDS_J1535467-
555656) with the longest pulsation period known in our Galaxy. The period of 78.14 days is …

An analysis of the properties of ultra-long-period Cepheids (ULPs) could significantly
contribute to understanding the Hubble constant tension, eg, the current discrepancy …

We predict the existence of α Ori B, a low-mass companion orbiting Betelgeuse. This is
motivated by the presence of a 2170 day long secondary period (LSP) in Betelgeuse's …

We use one-dimensional hydrodynamic calculations combined with synthetic stellar
population models of the Magellanic Clouds to study the onset of self-excited pulsation in …

Gaia is an astrometric space experiment that is measuring positions, proper motions as well
as parallaxes for a huge number of stars. It operates a medium-dispersion spectrometer, the …

At the core of the Gaia mission is a multi-epoch survey consisting of astrometric, photometric,
spectrophotometric, and spectroscopic measurements. The astrometric time series provides …

ABSTRACT Context. The Gaia satellite constitutes one of ESA's cornerstone missions. Being
primarily an astrometric space experiment measuring positions, proper motions, and …

As reported in the 2018-2021 report, the ESA satellite Gaia has been in routine operation
since July 2014 performing a continuous all-sky scan and observing all point-like sources …