Beta Boötis the ROSAT satellite was used to observe an X-ray flare on Beta Boötis, which released an estimated . This was the first such observation for a low-activity star of this type. The flare may be explained by an as yet unobserved M-type dwarf companion star. Beta Boötis Beta Boötis (β Boötis, abbreviated Beta Boo, β Boo), also named Nekkar, is a star in the northern constellation of Boötes. It has an apparent visual magnitude of 3.5, making it one of the brighter members of the constellation. In the modern constellation, it marks the head of Boötis the herdsman. Based upon
Cancer (constellation) as a lobster. Richard Allen, in "Star-names and Their Meanings", lists names for the constellation as follows: In Ancient Greece, Aratus called the crab "Καρκινος" ("Karkinos"), which was followed by Hipparchus and Ptolemy. The Alfonsine tables called it "Carcinus", a Latinized form of the Greek word. Eratosthenes extended this as "Καρκινος", "Ονοι", "και Φατνη" ("Karkinos", "Onoi", "kai Fatne"): the Crab, Asses, and Crib. In Ancient Rome, Manilius and Ovid called the constellation "Litoreus" (shore-inhabiting). "Astacus" and "Cammarus" appear in various classic writers, while it is called "Nepa" in Cicero's "De Finibus" and the works of Columella, Plautus, and Varro; all