Space

December 12, 2012

NASA Astrobiology Institute shows how wide binary stars form

Using computer simulations, scientists from the NASA Astrobiology Institute team at the University of Hawaii are shedding light on a question that has challenged astronomers for years: What causes wide binary stars?

Binary stars are pairs of stars that orbit each other. Wide binary stars are separated by as much as one light-year in their orbits, farther apart than some stellar nurseries are wide. Astronomers have known about such distant pairs for a long time but have not understood how they form.

Researchers simulated the complex motions of newborn triple stars still embedded in their nascent cloud cores. They studied the motions 180,000 times and concluded the widest binary systems began as three stars, not just two. This research appears in a paper to be published in the Dec. 13 issue of the journal Nature and was released last week online.

Most stars are born in small, compact systems with two or more stars at the center of a cloud core. When more than two stars share a small space, they gravitationally pull on each other in a chaotic dance. The least massive star often is kicked to the outskirts of the cloud core while the remaining stars grow larger and closer by feeding on the dense gas at the center of the cloud core.

If the force of the kick is not forecful enough, the runt star will not escape, but instead begin a very wide orbit of the other two, creating a wide binary. However, sometimes astronomers find only two stars in a wide binary. This means either the star system formed differently or something happened to one of the original binary pair.

“What may have happened is that the stars in the close binary merged into a single larger star,” said the paper’s lead author, Bo Reipurth of the Institute for Astronomy at the University of Hawaii at Manoa. “This can happen if there is enough gas in the cloud core to provide resistance to their motion. As the two stars in the close binary move around each other surrounded by gas, they lose energy and spiral toward each other. Sometimes there is so much gas in the core that the two close stars spiral all the way in and collide with each other in a spectacular merging explosion.”

The wide binary nearest to Earth is Alpha Centauri. The star itself is a close binary. Alpha Centauri has a small companion, Proxima Centauri, which orbits at a distance of about one-quarter of a light-year, or 15,000 times the distance between Earth and the sun. All three stars were born close together several billion years ago, before a powerful dynamic kick sent Proxima out into its wide path, where it has been orbiting ever since.

NASA’s Kepler mission already has proven that more than one planet can form and persist in the stressful realm of a binary star, a testament to the diversity of planetary systems in our galaxy.

NASA supported the University of Hawaii work through a cooperative agreement with NASA’s Ames Research Center, Moffett Field, Calif., and the NASA Astrobiology Institute, which is a partnership between NASA, 15 U.S. teams, and 10 international consortia. The research on wide binary stars included the University of Turku in Finland.

 




All of this week's top headlines to your email every Friday.


 
 

 

Headlines July 25, 2014

News: VA reform bills stalled by partisan bickering - Plans for a comprehensive Veterans Affairs Department reform bill that appeared all but finished a month ago devolved into partisan bickering and funding fights July 24, casting doubt on the future of a deal.   Business: Airbus, Boeing, Lockheed announce bids on Danish fighter competition; Saab withdraws -...
 
 

News Briefs July 25, 2014

Marines investigate corporal who vanished in Iraq U.S. Marine Corp officers are launching a formal investigation into whether a Lebanese-American Marine deserted his unit in Iraq or later after returning to the United States. A spokesman for the 2nd Marine Expeditionary Force at Camp Lejeune said July 24 that Cpl. Wassef Ali Hassoun is being...
 
 
Air Force photograph by A1C Erin OíShea

U.S. Forces display military might at Farnborough

Air Force photograph by A1C Erin O’Shea Capt. Tom Meyers discusses the F-15E Strike Eagle’s capabilities with spectators July 17, 2014, at the Farnborough International Airshow in England. Public access was granted ...
 

 
raptors4

Raptors, Falcons fuel up in desert skies

Three U.S. Air Force F-22 Raptors assigned to the 325th Fighter Wing, Tyndall Air Force Base, Fla., fly alongside a KC-135 Stratotanker assigned to the 93rd Air Refueling Squadron, Fairchild AFB, Wash., during Red Flag 14-3, Ju...
 
 
lm-kmax

Lockheed Martin’s unmanned cargo helicopter team returns from deployment

After lifting more than 4.5 million pounds of cargo and conducting thousands of delivery missions for the U.S. Marine Corps, the Lockheed Martin and Kaman Aerospace Corporation K-MAX cargo unmanned aircraft system has returned ...
 
 
Air Force photograph by A1C Thomas Spangler

Sun sets on Red Flag 14-3

Air Force photograph by A1C Thomas Spangler The sun sets behind a row of F-16 Fighting Falcons during Red Flag 14-3, July 16, 2014, at Nellis Air Force Base, Nev. Red Flag provides a series of intense air-to-air combat scenario...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>