A red dwarf is a small, cool, long-lived star, the most common type in the galaxy. Because they are faint, their habitable zones lie close in, where planets are easier to detect, which makes red dwarfs prime targets in the search for life. But they flare violently and bathe nearby worlds in radiation, and several studied planets, including LHS 3844 b, appear to have lost their atmospheres entirely, a central worry for whether red-dwarf planets can be habitable.