Context. The known mega metal-poor (MMP) and hyper metal-poor (HMP) stars, with [Fe/H] < −6.0 and < −5.0, respectively, likely belong to the CEMP-no class, namely, carbon-enhanced stars with little or no second peak neutron-capture elements. They are likely second-generation stars, and the few elements measurable in their atmospheres are used to

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We present the discovery of TOI-1420b, an exceptionally low-density (ρ = 0.08 ± 0.02 g cm -3) transiting planet in a P = 6.96 days orbit around a late G-dwarf star. Using transit observations from TESS, LCOGT, Observatoire Privé du Mont, Whitin, Wendelstein, OAUV, Ca l'Ou, and KeplerCam, along with radial velocity observations from HARPS-N and NEID

Protoneutron stars formed during core-collapse supernovae are hot and dense environments that contain a sizable population of muons. If these interact with new long-lived particles with masses up to roughly 100 MeV, the latter can be produced and escape from the stellar plasma, causing an excessive energy loss constrained by observations of SN

In 2013 a dearth of close-in planets around fast-rotating host stars was found using statistical tests on Kepler data. The addition of more Kepler and Transiting Exoplanet Survey Satellite (TESS) systems in 2022 filled this region of the diagram of stellar rotation period (P rot) versus the planet orbital period (P orb). We revisited the P rot

We present a novel approach to the determination of the pointing of Imaging Atmospheric Cherenkov Telescopes (IACTs) using the trajectories of the stars in their camera's field of view. The method starts with the reconstruction of the star positions from the Cherenkov camera data, taking into account the point spread function of the telescope, to