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
Cerberus (constellation) Cerberus (constellation) Cerberus is an obsolete constellation created by Hevelius, whose stars are now included in the constellation Hercules. It was depicted as a three-headed snake that Hercules is holding in his hand. The constellation is no longer in use. This constellation "figure typified the serpent ... infesting the country around Taenarum the Μέτωπον of Greece, the modern Cape Matapan." The presence of Cerberus (Kerberos) at Taenarum (Tainaron) is mentioned by Strabo, Statius, and Seneca the Younger. John Senex combined this constellation with the likewise obsolete constellation Ramus Pomifer, an apple branch held by Hercules, in his 1721 star map