Open clusters are the place where a large fraction of massive stars form, evolve, and eventually die, giving birth to stellar-mass black holes. If a significant fraction of black holes receives low (≲ km /s) kicks at birth, even open clusters with low escape velocities can efficiently retain them. Thanks to the exquisite astrometric and photometric measurement by Gaia, we have now the...
The death of massive stars can impart an impulse to the remnant black holes (BHs) and neutron stars (NSs) during supernova explosions. This impulse, also known as a natal kick (NK), can propel the compact objects to substantial space velocities. Understanding the motions perturbed by NKs not only sheds light on the underlying supernova physics but also plays a crucial role in the evolution of...
We report on optical observations of transient objects detected by ESA Gaia, DPAC and the Photometric Science Alerts Team (http://gsaweb.ast.cam.ac.uk/alerts). Ground-based observations contribute significantly to achieving advances in studies of these objects, especially in their classifying. In 2016, we started to observe Gaia transients using the telescopes with diameters up to 2 m. Our...
Gaia Blue (BP) and Red (RP) Photometer low-resolution spectral data is one of the exciting new products in Gaia Data Release 3 (Gaia DR3). However, analogous LDS (low dispersive spectral data) data also available in numerous historical photographic sky surveys (access after digitization).
My estimate is more than 100 mil LDS star spectra covering time period of more than 60 years in these...
Transients can be defined as astrophysical phenomena whose duration is significantly lower than the typical timescale of the stellar and galactic evolution (from seconds to years in contrast to millions or billions of years). Supernovae, novae, gamma-ray burst,..., are some examples of transient events. In most cases, a fast, multiwavelength characterisation is required to properly ...
In June 2022, the Gaia Data Release 3, completing the previous EDR3, made possible a 3D kinematical and dynamical analysis of 33 million stars in the Milky Way and its satellites. In addition, Gaia DR3 has opened a new era of all-sky chemo-physical analysis of stellar populations thanks to the nearly 5.6 million stars observed by the Radial Velocity Spectrometer and parameterized by the...
Despite the classical interpretation of RR Lyrae as old and metal-poor population II stars, it is well known that metal-rich (up to solar values) RR Lyrae stars exist in the solar vicinity. Thanks to the unprecedented Gaia capabilities (Gaia DR2 and Gaia DR3), we found that the metal-rich RR Lyrae stars are present all over the Galactic disc, well beyond the Solar neighbourhood. The...
