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.


 
 

 

NASA seeks proposals to develop capabilities for deep space exploration, journey to Mars

NASA is soliciting proposals for concept studies or technology development projects that will be necessary to enable human pioneers to go to deep space destinations such as an asteroid and Mars. Through a Broad Area Announcemen NASA released Oct. 28, the agency seeks to use public-private partnerships to share funding to develop advanced propulsion, habitation...
 
 
Photograph courtesy of  NASA/CXC/Stanford/I. Zhuravleva et al

NASA’S Chandra Observatory identifies impact of cosmic chaos on star birth

Photograph courtesy of NASA/CXC/Stanford/I. Zhuravleva et al Chandra observations of the Perseus and Virgo galaxy clusters suggest turbulence may be preventing hot gas there from cooling, addressing a long-standing question of ...
 
 

NASA hosts first agency-wide social media event for Orion’s first flight test

NASA invites social media followers to apply for credentials to get a preview of the Orion spacecraft’s first flight test during NASA Social events Dec. 3 at each of its 10 centers. Orion will launch on a United Launch Alliance Delta IV Heavy rocket from Space Launch Complex 37 at Cape Canaveral Air Force Station,...
 

 
nasa-spacex

Critical NASA science returns to Earth aboard SpaceX Dragon spacecraft

SpaceX’s Dragon cargo spacecraft splashed down at 3:39 p.m., EDT, Oct. 25, in the Pacific Ocean, approximately 300 miles west of Baja California, returning 3,276 pounds of NASA cargo and science samples from the Internati...
 
 
NASA, ESA, PSI, JHU/APL, STScI/AURA image

Close encounters: Comet Siding Spring seen next to Mars

NASA, ESA, PSI, JHU/APL, STScI/AURA image This composite NASA Hubble Space Telescope Image captures the positions of comet Siding Spring and Mars in a never-before-seen close passage of a comet by the Red Planet, which happened...
 
 

NASA Astronaut Scott Kelly shares bullying prevention message ahead of one-year mission

NASA astronaut Scott Kelly, who is scheduled to fly on a one-year spaceflight mission in 2015, is lending his voice to help reduce childhood bullying. As part of Bullying Prevention Awareness Month, Kelly recorded a special message encouraging bystanders to take action. “Be more than just a bystander,” said Kelly in the message. “Take action...
 




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>