Rasalhague (Alpha Ophiuchi) is the brightest star in the constellation Ophiuchus. Its name, which refers to the whole constellation, comes from an Arabic phrase meaning "the Head of the Serpent Collector." Rasalhague is a giant A star that has probably recently exhausted its core hydrogen reserves. It has a faint, very close companion only 0.5 arcseconds away, equivalent to 7 astronomical units (AU) in real terms, that orbits with a period of 8.7 years.