December 12, 2012
Innovative Telescope Reveals Vega Star Is Older Than We Thought
April Flowers for redOrbit.com - Your Universe Online
For thousands of years, astronomers have used Vega — the fifth brightest star in the night sky and the brightest in the constellation Lyra — as a touchstone to measure the brightness of other stars. Now, a new study from the University of Michigan demonstrates that Vega may be more than 200 million years older than scientists previously believed.
Researchers were able to estimate Vega´s age by precisely measuring the star´s spin speed with the Michigan Infrared Combiner (MIRC), a tool developed by associate professor of astronomy at the university John Monnier. The results of this study were recently published in Astrophysical Journal Letters.
Installed at the Georgia State Center for High Angular Resolution Astronomy Array (CHARA), the MIRC collects and combines light from six telescopes, making it appear as though it were coming from a single telescope 100 times the size of the Hubble Space Telescope. The MIRC allows astronomers to zoom in by boosting resolution, allowing the researchers to observe the shape and surface characteristics of stars that would otherwise look like mere glowing dots even through the most powerful telescopes. Scientists can then calculate how fast they rotate and deduce their inner workings by tracking stars' surface characteristics.
Just visible toward the west at sunset, Vega is a summer star in the Northern Hemisphere that is relatively close to Earth — just 25 light years away.
In 2006 astronomers discovered that Vega is spinning so fast that it is nearly flinging itself apart. A number of critical details surrounding the star, however, remain a mystery. For instance, Vega's exact rotation rate is one of the central debates. Nailing down the rotation rate is essential to gauge both the star's mass and age. Other debates concerning Vega deal with the its tilt as viewed from Earth and the amount of turbulence in the system from roiling gases at the star's surface.
Monnier and his team have used MIRC's unprecedented resolution to correct competing estimates of Vega's rotation rate and other properties. The data that they collected indicates that the star rotates once every 17 hours, rather than once every 12 as previously thought. The team also confirmed Vega's mass to be over twice that of our sun.
"Vega continues to challenge and surprise us," Monnier said in a statement. "We found out not too long ago that it has a disk of dusty debris, or a leftover solar system, around it. Then we found out it was a rapid rotator. It's a reference point for other stars, but it certainly isn't boring or normal."
The results of this study will help astronomers build more accurate models of stars, allowing them to create simulations of those that are too far away to observe and thus gain a better understanding of their life cycles.