Hubble Discovers Hydrogen-Burning White Dwarfs Enjoying Slow Aging
Mockingbird writes:
Video from HubbleESA that gives a zoom in on the Globular Cluster Messier 13. Also at the non-YT site: ESAHubble.org.
(Related story on a study comparing Messier 3 and 13 at Phys.org.)
The prevalent view of white dwarfs as inert, slowly cooling stars has been challenged by observations from the NASA/ESA Hubble Space Telescope. An international group of astronomers have discovered the first evidence that white dwarfs can slow down their rate of aging by burning hydrogen on their surface.
"We have found the first observational evidence that white dwarfs can still undergo stable thermonuclear activity," explained Jianxing Chen of the Alma Mater Studiorum Universita di Bologna and the Italian National Institute for Astrophysics, who led this research. "This was quite a surprise, as it is at odds with what is commonly believed."
White dwarfs are the slowly cooling stars which have cast off their outer layers during the last stages of their lives. They are common objects in the cosmos; roughly 98% of all the stars in the Universe will ultimately end up as white dwarfs, including our own Sun. Studying these cooling stages helps astronomers understand not only white dwarfs, but also their earlier stages as well.
To investigate the physics underpinning white dwarf evolution, astronomers compared cooling white dwarfs in two massive collections of stars: the globular clusters M3 and M13 . These two clusters share many physical properties such as age and metallicity but the populations of stars which will eventually give rise to white dwarfs are different. In particular, the overall color of stars at an evolutionary stage known as the Horizontal Branch are bluer in M13, indicating a population of hotter stars. This makes M3 and M13 together a perfect natural laboratory in which to test how different populations of white dwarfs cool.
Read more of this story at SoylentNews.