Aastronomers discover new type of variable star

A new type of variable star was discovered by a team of Swiss astronomers from the Geneva Observatory who measured minute variations in stellar brightness. The results are based on measurements of the brightness of more than 3,000 stars in the star cluster NGC 3766 during a seven-year period, TG Daily reported Tuesday. The measurements revealed how 36 of the cluster's stars had tiny regular variations in brightness at 0.1 percent of the stars' normal brightness, researchers said. The astronomers found the variations lasted 2- to 20 hours. The new class of variable stars hasn't been named, TG Daily said. "We have reached this level of sensitivity thanks to the high quality of the observations, combined with a very careful analysis of the data," research team leader Nami Mowlavi said, "[and] also because we have carried out an extensive observation program that lasted for seven years. It probably wouldn't have been possible to get so much observing time on a bigger telescope." The team used a 1.2-meter telescope. Although the cause of the variability hasn't been determined, researchers said some of the stars seem to rotate very fast, spinning at speeds more than half of their critical velocity, where stars become unstable and cast material into space, TG Daily said. "The very existence of this new class of variable stars is a challenge to astrophysicists," team member Sophie Saesen said. "Current theoretical models predict that their light is not supposed to vary periodically at all, so our current efforts are focused on finding out more about the behavior of this strange new type of star."