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.


 
 

 
Image courtesy of NASA/CXC/DSS/Magellan

NASA’s Chandra Observatory finds cosmic showers halt galaxy growth

Image courtesy of NASA/CXC/DSS/Magellan A study of over 200 galaxy clusters, including Abell 2597 shown here, with NASAís Chandra X-ray Observatory has revealed how an unusual form of cosmic precipitation stifles star formatio...
 
 
Image courtesy of NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

NASA spacecraft nears historic dwarf planet arrival

Image courtesy of NASA/JPL-Caltech/UCLA/MPS/DLR/IDA NASA’s Dawn spacecraft took these images of dwarf planet Ceres from about 25,000 miles away Feb. 25, 2015. Ceres appears half in shadow because of the current position o...
 
 

Northrop Grumman’s AstroMesh reflector successfully deploys for NASA’s SMAP satellite

The NASA Jet Propulsion Laboratory successfully deployed the mesh reflector and boom aboard the Soil Moisture Active Passive spacecraft, a key milestone on its mission to provide global measurements of soil moisture. Launched Jan. 31, SMAP represents the future of Earth Science by helping researchers better understand our planet. SMAP’s unmatched data capabilities are enabled...
 

 
NASA photograph by Brian Tietz

NASA offers space tech grants to early career university faculty

NASA photograph by Brian Tietz Tensegrity research is able to simulate multiple forms of locomotion. In this image, a prototype tensegrity robot reproduces forward crawling motion. NASA’s Space Technology Mission Director...
 
 

NASA releases first global rainfall, snowfall map from new mission

Like a lead violin tuning an orchestra, the GPM Core Observatory – launched one year ago on Feb. 27, 2014, as a collaboration between NASA and the Japan Aerospace Exploration Agency – acts as the standard to unify precipitation measurements from a network of 12 satellites. The result is NASA’s Integrated Multi-satellite Retrievals for GPM...
 
 

New NASA Earth Science Missions expand view of our home planet

Four new NASA Earth-observing missions are collecting data from space with a fifth newly in orbit ñ after the busiest year of NASA Earth science launches in more than a decade. On Feb. 27, 2014, NASA and the Japan Aerospace Exploration Agency launched the Global Precipitation Measurement Core Observatory into space from Japan. Data from...
 




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>