Friday, April 3, 2009

New Close-up Shows Binary Stars in Orion's Heart

Astronomers have caught their sharpest look of a double star system deep in the heart of the Orion nebula.

The result is an ultra-clear glimpse of Theta 1 Orionis C, a mismatched pair of stars locked in orbit around one another about 1,350 light-years from Earth.

Once thought to be a single star, Theta 1 Orionis C is the brightest and most dominant stellar system inside the dense star-forming region of Orion's beautiful Trapezium Cluster. Infrared views of the system ultimately showed its dual nature, which shines through with renewed clarity in the new image.

Researchers used the European Southern Observatory's Very Large Telescope Interferometer (VLTI), which combines data from multiple telescopes into one image, to make the new observation.

The Chile-based observatory yielded a photograph with a resolution of about 2 milliarcseconds. That's about the equivalent of how a car on the moon would look to a human staring at it from the surface of the Earth, or the view from a hypothetical space telescope with a 426-foot (130-meter) main mirror. For comparison, the main mirror of the Hubble Space Telescope is about 7.8 feet (2.4 meters) wide.

"Our observations demonstrate the fascinating new imaging capabilities of the VLTI," said study co-investigator Gerd Weigelt of the Max-Planck-Institute for Radio Astronomy. "This infrared interferometry technique will certainly lead to many fundamental new discoveries."

In addition to the new image of Theta 1 Orionis C, Weigelt and colleague Stefan Kraus found that the stars orbit each other once every 11 years. The smaller of the pair is about nine times as massive as the sun, while its larger partner weighs in at whopping 38 solar masses.

Solar wind from the paired stars shapes the disks of protoplanetary dust of other nearby stars, researchers said. The new images and data will help astronomers better understand how massive stars form within the Orion nebula, they added.

Original here

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