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
Taurus (constellation) is a white, spectral class B7 III giant star known as "El Nath", which comes from the Arabic phrase "the butting", as in butting by the horns of the bull. At magnitude 1.65, it is the second brightest star in the constellation, and shares the border with the neighboring constellation of Auriga. As a result, it also bears the designation Gamma Aurigae. Zeta Tauri (the proper name is "Tianguan") is an eclipsing binary star that completes an orbit every 133 days. A degree to the northwest of ζ Tauri is the Crab Nebula (M1), a supernova remnant. This expanding nebula