New technique reveals the age of massive Southern Cross star
An international team of astronomers from Australia, the United States and Europe has for the first-time unlocked the interior structure of Beta Crucis - a bright blue giant star that features on the flags of Australia, Brazil, New Zealand, Papua New Guinea and Samoa. With an entirely new approach, the team led by Dr Daniel Cotton, found the star to be 14.5 times as massive as the Sun and as young as 11 million years old, making it the heaviest star with an age determined from asteroseismology ever. The findings will provide new detail on how stars live and die, and how they impact the Galaxy's chemical evolution. To crack the star's age and mass, the research team combined asteroseismology, the study of a star's regular movements, with polarimetry, the measurement of the orientation of light waves. Asteroseismology relies on seismic waves bouncing around the interior of a star and producing measurable changes in its light. Probing the interiors of heavy stars that will later explode as supernovae has traditionally been difficult. "I wanted to investigate an old idea," lead author Dr Cotton, from The Australian National University (ANU), and Monterey Institute for Research in Astronomy in the USA, said. "It was predicted in 1979 that polarimetry had the potential to measure the interiors of massive stars, but it's not been possible until now." Study co-author Professor Jeremy Bailey from the University of New South Wales (UNSW) said: "The size of the effect is quite small.
