Space

July 26, 2013

NASA’s WISE finds mysterious centaurs may be Comets

The true identity of centaurs, the small celestial bodies orbiting the sun between Jupiter and Neptune, is one of the enduring mysteries of astrophysics.

Are they asteroids or comets? A new study of observations from NASA’s Wide-field Infrared Survey Explorer finds most centaurs are comets.

Until now, astronomers were not certain whether centaurs are asteroids flung out from the inner solar system or comets traveling in toward the sun from afar. Because of their dual nature, they take their name from the creature in Greek mythology whose head and torso are human and legs are those of a horse.

“Just like the mythical creatures, the centaur objects seem to have a double life,” said James Bauer of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. Bauer is lead author of a paper published online July 22 in the Astrophysical Journal. “Our data point to a cometary origin for most of the objects, suggesting they are coming from deeper out in the solar system.”

Cometary origin means an object likely is made from the same material as a comet, may have been an active comet in the past, and may be active again in the future.

The findings come from the largest infrared survey to date of centaurs and their more distant cousins, called scattered disk objects. NEOWISE, the asteroid-hunting portion of the WISE mission, gathered infrared images of 52 centaurs and scattered disk objects. Fifteen of the 52 are new discoveries. Centaurs and scattered disk objects orbit in an unstable belt. Ultimately, gravity from the giant planets will fling them either closer to the sun or farther away from their current locations.

Although astronomers previously observed some centaurs with dusty halos, a common feature of outgassing comets, and NASA’s Spitzer Space Telescope also found some evidence for comets in the group, they had not been able to estimate the numbers of comets and asteroids.

Infrared data from NEOWISE provided information on the objects’ albedos, or reflectivity, to help astronomers sort the population. NEOWISE can tell whether a centaur has a matte and dark surface or a shiny one that reflects more light. The puzzle pieces fell into place when astronomers combined the albedo information with what was already known about the colors of the objects. Visible-light observations have shown centaurs generally to be either blue-gray or reddish in hue. A blue-gray object could be an asteroid or comet. NEOWISE showed that most of the blue-gray objects are dark, a telltale sign of comets. A reddish object is more likely to be an asteroid.

“Comets have a dark, soot-like coating on their icy surfaces, making them darker than most asteroids,” said the study’s co-author, Tommy Grav of the Planetary Science Institute in Tucson, Ariz. “Comet surfaces tend to be more like charcoal, while asteroids are usually shinier like the moon.”

The results indicate that roughly two-thirds of the centaur population is comets which came from the frigid outer reaches of our solar system. It is not clear whether the rest are asteroids. The centaur bodies have not lost their mystique entirely, but future research from NEOWISE may reveal their secrets further.

The paper is available online at:  http://iopscience.iop.org/0004-637X/773/1/22/

JPL, managed by the California Institute of Technology in Pasadena, managed and operated WISE for NASA’s Science Mission Directorate. The NEOWISE portion of the project was funded by NASA’s Near Earth Object Observation Program. WISE completed its key mission objective, two scans of the entire sky, in 2011 and has been hibernating in space since then.

 




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


 
 

 

Headlines September 2, 2014

News: Debris yields clues that pilot never ejected - When investigators were finally able to safely enter the crash site of an F-15C “Eagle” fighter jet on the afternoon of Aug. 27, they made a grim discovery that concluded more than 30 hours of searching – the pilot never managed to eject from the aircraft.  ...
 
 

News Briefs September 2, 2014

Pentagon: Iraq operations cost $560 million so far U.S. military operations in Iraq, including airstrikes and surveillance flights, have cost about $560 million since mid-June, the Pentagon said Aug. 29. Rear Adm. John Kirby, the Pentagon press secretary, said the average daily cost has been $7.5 million. He said it began at a much lower...
 
 

Unmanned aircraft partnership reaches major milestone

A team of research students and staff from Warsaw University of Technology have successfully demonstrated the first phase of flight test and integration of unmanned aircraft platforms with an autonomous mission control system. The demonstration marks a significant milestone in a partnership between the university and Lockheed Martin that began earlier this year. This is...
 

 

Raytheon delivers first Block 2 Rolling Airframe Missiles to US Navy

Raytheon delivered the first Block 2 variant of its Rolling Airframe Missile system to the U.S. Navy as part of the company’s 2012 Low Rate Initial Production contract. RAM Block 2 is a significant performance upgrade featuring enhanced kinematics, an evolved radio frequency receiver, and an improved control system. “As today’s threats continue to evolve,...
 
 
Courtesy photograph

Two Vietnam War Soldiers, one from Civil War to receive Medal of Honor

U.S. Army graphic Retired Command Sgt. Maj. Bennie G. Adkins and former Spc. 4 Donald P. Sloat will receive the Medal of Honor for actions in Vietnam. The White House announced Aug. 26 that Retired Command Sgt. Maj. Bennie G. A...
 
 

Sparks fly as NASA pushes limits of 3-D printing technology

NASA has successfully tested the most complex rocket engine parts ever designed by the agency and printed with additive manufacturing, or 3-D printing, on a test stand at NASA’s Marshall Space Flight Center in Huntsville, Ala. NASA engineers pushed the limits of technology by designing a rocket engine injector – a highly complex part that...
 




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>