C/2017 K2 (Pan-STARRS) is an Oort cloud comet discovered in May 2017. Ground observations have revealed that this long-period comet was active at heliocentric distance of 35 au. At such a distance, activity cannot be driven by the sublimation or the exothermic crystallization of water ice. We assume that the activity of comet C/2017 K2 may be

We combine photometry of Eris from a 6 month campaign on the Palomar 60 inch telescope in 2015, a 1 month Hubble Space Telescope WFC3 campaign in 2018, and Dark Energy Survey data spanning 2013-2018 to determine a light curve of definitive period 15.771 ± 0.008 days (1σ formal uncertainties), with nearly sinusoidal shape and peak-to-peak flux

Context. Blue supergiants (BSGs) are key objects for studying the intermediate phases of massive star evolution because they are very useful to constrain evolutionary models. However, the lack of a holistic study of a statistically significant and unbiased sample of these objects has lead to several long-standing questions about their physical

Using one of the largest volumes of the hydrodynamical cosmological simulation suit Magneticum, we study the evolution of protoclusters identified at redshift ≈ 4, with properties similar to the well-observed protocluster SPT2349-56. We identify 42 protoclusters in the simulation as massive and equally rich in substructures as observed, confirming

Supermassive black holes (SMBHs) and nuclear star clusters (NSCs) co-exist in many galaxies. While the formation history of the black hole is essentially lost, NSCs preserve their evolutionary history imprinted onto their stellar populations and kinematics. Studying SMBHs and NSCs in tandem might help us to ultimately reveal the build-up of galaxy

Context. Automated analyses of Gaia astrometric data have led to the discovery of many new high-quality open cluster candidates. When a good determination of their parameters is available, these objects become excellent tools for investigating the properties of our Galaxy. Aims: We explore whether young open clusters can be readily identified from