Star Search Solves Historic Puzzle
Astronomers have solved a 400-year-old cosmic mystery, locating the missing companion star that played a crucial role in the titanic supernova witnessed by Danish astronomer Tycho Brahe on Nov. 11, 1572.
Brahe did not know precisely what he had seen, but his careful documentation of the brilliant star that suddenly appeared in the constellation Cassiopeia and then slowly faded away allowed modern researchers to conclude that he had witnessed a Type 1a supernova -- the death of a star in an explosion 1 billion times as bright as the sun.
Type 1a supernovas are believed to be produced in a binary system made up of a normal star and a burned-out star called a white dwarf. The normal star spills matter -- mostly hydrogen -- into the white dwarf, eventually causing the dwarf star to explode. In the process, the normal star is blasted off into space with an increased velocity.
Astronomers have been searching for the star that escaped from Brahe’s supernova. Astronomer Pilar Ruiz-Lapuente of the University of Barcelona and her colleagues reported in this week’s edition of the journal Nature that they had discovered a likely candidate.
After seven years of searching using a number of telescopes, the team has found an aging version of our own sun that is in the right area, about 10,000 light-years from Earth, and moving about three times as fast as other stars in the region.
If this star, called Tycho G, is indeed the companion star, it confirms the basic theory about how supernovas occur, experts said.
When Brahe first noticed the supernova, it was about as bright as of the planet Jupiter. It soon equaled Venus in brightness and, for a period of two weeks, could even be seen in the daytime.
By the end of November 1572, it began to fade and change color, from bright white to yellow and orange to faint reddish light, eventually disappearing from view in March 1574.
The observation was important because it helped 16th century astronomers abandon the idea of an immutable universe.
