European Southern Observatory (ESO) has been using the new SPHERE instrument on the Very Large Telescope (VLT) to look for a brown dwarf they assumed is orbiting the double star V471 Tauri (in the constellation Taurus), according to a press release. SPHERE has operated beautifully and provided the astronomers with - nada. Nothing. Bupkis.
SPHERE has given astronomers "the best look so far," but the predicted dwarf is missing, which means the strange behavior of V471 Tauri has not been explained. The surprise findings are published in the first science paper revealing SPHERE's observations published in Astrophysical Journal Letters.
Some star pairings do not have identical stars. One star might have a higher mass and upon expanding to become a red giant, some of its material is transferred to the star with lower mass. The material ends up a gaseous envelope surrounding both stars. When the cloud dissipates, the stars get closer and form a tight couple consisting of one white dwarf and one normal star. Pairs like that are known as post-common-envelope binaries.
This is the case of V471 Tauri, named so because it is the 471st star - rather, pair of stars - to be identified in the constellation Taurus. V471 Tauri, estimated to be 600 million years old, is a member of the Hyades star cluster. It is located about 163 light-years away from Earth.
"There are many papers suggesting the existence of such circumbinary objects, but the results here provide damaging evidence against this hypothesis," said Hardy, according to the press release.
Other theories have been proposed. One possible theory is that magnetic field variations in the larger of the two stars causes changes similar to those seen in our sun.
"A study such as this has been necessary for many years, but has only become possible with the advent of powerful new instruments such as SPHERE," said Hardy, according to the press release. "This is how science works: observations with new technology can either confirm, or as in this case disprove, earlier ideas. This is an excellent way to start the observational life of this amazing instrument."
