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Study Reveals Secrets Of Binary Stars Through Red Explosions

January 25, 2013
Image Caption: Hubble space telescope images show an expanding burst of light from a red supergiant star. Credit: NASA/ESA

April Flowers for redOrbit.com – Your Universe Online

Astrophysicists have debated the outcome of two binary stars — stars that orbit each other — coming together in a “common envelope” for a long time. A new study from the University of Alberta has finally provided some answers.

Theoretical astrophysicist Natalia Ivanova has revealed the workings of a celestial event that produces an explosion so powerful its luminosity approaches that of a supernova.

“When this dramatic cannibalizing event ends there are two possible outcomes: the two stars merge into a single star or an initial binary transforms into an exotic short-period one,” Ivanova said in a statement.

Believed to take anywhere from a dozen days to a few hundred years to complete, the event happens in an extremely fast period in terms of celestial goings-on.

Ivanova said that more than half the stars in our Universe are binary stars, but prior to this study it was not known what a common envelope event would look like.

The American Museum of Natural History (AMNH) explains the common envelope phenomenon: “In most binary star systems, mass is transferred between the two stellar components. Usually, the transfer of mass eventually stabilizes with the companion absorbing the new material at a constant rate as it settles into a ‘dynamically speaking’ steady orbit around the primary. However, in some systems, the process fails to stabilize. The primary star loses so much mass that the companion star is unable to accrete the new material. Instead, a cloud of mass known as a common envelope surrounds both stars.”

The research team analyzed the physics of what happens in the outer layers of a common envelope, finding that hot and ionized material in the envelope expands and cools. The study, published in a recent issue of Science, found that this releases energy in the form of a bright red outburst of light.

Ivanova and her team linked recently discovered luminous red novae — mysterious transients that are brighter than novae and just a bit less luminous than supernova — to these theoretically anticipated common envelope outbursts.

“Our research both provides a way to identify common envelope events and explains the luminosity generated during the common envelope event,” said Ivanova.


Source: April Flowers for redOrbit.com - Your Universe Online



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