Astronomers detect explosive, toxic gas in ancient brown dwarfAstronomers have detected the explosive, highly toxic gas phosphine (PH3), in the atmosphere of an ancient brown dwarf (Wolf 1130C) located 54 light-years from the Sun in the constellation Cygnus. Phosphine has long been recognised as a possible biosignature for anaerobic life, given that there are few natural sources in terrestrial planet atmospheres.