In 2013 April, the TeV blazar Markarian 421 underwent one of its most powerful emission outbursts recorded to date. An extensive multi-instrument campaign featuring MAGIC, VERITAS, and NuSTAR provided comprehensive very high-energy (VHE; E > 100 GeV) and X-ray coverage over nine consecutive days. The VHE flux peaked at approximately 15 times that

The formation of stellar structures in galaxies is intimately connected to all evolutionary processes. Violent mergers prevent or destroy fragile discs, while minor mergers are able to promote the formation of classical bulges. Secular evolution favours the formation of bars, rings, nuclear discs, etc. The assembly history of stellar structures

For low-mass stars (M < 1.4 M☉), the connection between stellar rotation and magnetic activity governs stellar spin-down, shapes the environments and habitability of their exoplanets, and provides an age-diagnostic via magneto-gyro-chronology. Recently, an unexpected phenomenon known as the 'rotational stalling' was discovered, where stars rotate

Context. The outer Galactic halo remains relatively unexplored, particularly regarding its metallicity distribution, merger debris, and the population of very and extremely metal-poor ([Fe/H] < -2.5) stars. Aims. Using photometric metallicities from the Pristine survey data release 1 (PDR1) and Pristine-Gaia synthetic (PGS) catalogue and Gaia DR3

Observations show that the first galaxy clusters were already assembling by z ~ 2-3, earlier and more massive than predicted by standard cosmological models. Understanding how these dense environments affect star formation provides direct insight into how galaxies form and evolve. SPOTLESS (Searching for Protoclusters through Observations Tracing

MATLAS-2019 (also known as NGC5846-UDG1) has attracted significant attention due to the ongoing debate surrounding its globular cluster (GC) population, with several studies addressing the issue, yet reaching little consensus. For this paper, we took advantage of HST's multi-wavelength coverage (F475W, F606W, and F814W observations) with the