A few remarkable examples of alternative cosmological theories are shown, ranging from a compilation of variations on the Standard Model (inhomogeneous universe, Cold Big Bang, varying physical constants or gravity law, zero-active mass, Milne cosmology, cyclical models), through the more distant quasi-steady-state cosmology, plasma cosmology, or

Elemental composition guides the formation, evolution, and atmosphere processes of the lowest-mass stars and brown dwarfs, or ultracool dwarfs (UCDs). While the vast majority of known UCDs are solar-metallicity objects in the Milky Way's thin disk, a rare subsample of metal-poor stellar and substellar subdwarfs are known in the Solar Neighborhood

In main-sequence, low-mass (<1.3 Solar mass) stars, rotation and magnetic activity decrease over time, with the spin-down thought to be due to angular momentum lost through magnetized winds. This magnetic activity heats the stellar atmospheres, leading to the production of Hα, ultraviolet (UV), and X-ray radiation, each originating from different