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-hubble

NASA unveils celestial fireworks as official image for Hubble 25th Anniversary

The brilliant tapestry of young stars flaring to life resemble a glittering fireworks display in the 25th anniversary NASA Hubble Space Telescope image, released to commemorate a quarter century of exploring the solar system an...
 
 
NASA illustration

NASA awards radiation challenge winners, launches next round

NASA illustration This illustration depicts our heliosphere, showing the approximate locations of Voyager 1 and Voyager 2 spacecraft. Galactic cosmic rays originate outside the heliosphere and stream in uniformly from all direc...
 
 
NASA photograph

Celebrate with NASA as agency commemorates Hubble’s 25th anniversary

NASA’s Hubble Space Telescope is turning 25 this year. The observatory has transformed our understanding of our solar system and beyond, and helped us find our place among the stars. NASA is celebrating the Hubble Space T...
 

 

ULA unveils America’s new rocket

https://www.youtube.com/watch?v=emmeil-0u5k&feature=player_embedded United Launch Alliance unveiled its Next Generation Launch System April 13 at the 31st Space Symposium. The new rocket, Vulcan, will transform the future of space by making launch services more affordable and accessible. The NGLS brings together decades of experience on ULA’s reliable Atlas and Delta vehicles, combin...
 
 
NASA/JHU APL/Carnegie Institution of Washington

NASA spacecraft achieves unprecedented success studying Mercury

NASA/JHU APL/Carnegie Institution of Washington NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft traveled more than six and a half years before it was inserted into orbit around Merc...
 
 

NASA selects American small business, research institution projects for further development

NASA has selected 149 research and technology proposals from American small businesses and research institutions that will enable NASA’s future missions into the solar system and beyond while benefiting America’s technology-driven economy right here on Earth. The selected proposals now will enter into negotiations for contract awards as part of Phase II of the agency’s...
 




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>