Ultracompact X-ray binaries (UCXBs) are a distinctive but elusive family of low-mass X-ray binaries (LMXBs) characterised by their tight orbits and degenerate donor stars. Here we present UltraCompCAT, the first online and comprehensive catalogue of UCXBs. The initial version of UltraCompCAT comprises 49 sources, including 20 confirmed UCXBs (those

The bright star λ Ser hosts a hot Neptune with a minimum mass of 13.6 M ⊕ and a 15.5 day orbit. It also appears to be a solar analog, with a mean rotation period of 25.8 days and surface differential rotation very similar to the Sun. We aim to characterize the fundamental properties of this system and constrain the evolutionary pathway that led to

There is controversy in the literature regarding whether distant, massive, and dusty starbursts selected at (sub)millimeter wavelengths can trace galaxy overdensities. We thus performed the first systematic search for distant protoclusters around a homogeneously selected sample of 12 spectroscopically confirmed submillimeter galaxies (SMGs) at z ∼

The hydrogen Paschen lines are known activity indicators, but studies of them in M dwarfs during quiescence are as rare as their reports in flare studies. This situation is mostly caused by a lack of observations, owing to their location in the near-infrared regime, which is covered by few high-resolution spectrographs. We study the Paβ line, using

Within a simulated Milky Way-like galaxy, we identify and analyse analogues of the Gaia-Enceladus (GE), Kraken, and Sequoia mergers that each matches remarkably well observational results, including in velocity and chemical abundance space, and their distributions in the j z-Energy plane. The Kraken analogue is the earliest merger and has the

We present the first optical study of the supernova remnant (SNR) G7.7-3.7, with the aim of determining its evolutionary phase since it has been suggested to be the remnant of SN 386 AD. We obtained narrow-band images in the filters H α + [N II], H β, [O III], [S II] that revealed faint optical emission in the southern region of the SNR consisting