Space

June 14, 2013

Hubble uncovers evidence of farthest planet forming from its star

nasa-hubble
using NASA’s Hubble Space Telescope have found compelling evidence of a planet forming 7.5 billion miles away from its star, a finding that may challenge current theories about planet formation.

Of the almost 900 planets outside our solar system that have been confirmed to date, this is the first to be found at such a great distance from its star. The suspected planet is orbiting the diminutive red dwarf TW Hydrae, a popular astronomy target located 176 light-years away from Earth in the constellation Hydra the Sea Serpent.

Hubble’s keen vision detected a mysterious gap in a vast protoplanetary disk of gas and dust swirling around TW Hydrae. The gap is 1.9 billion miles wide and the disk is 41 billion miles wide. The gap’s presence likely was caused by a growing, unseen planet that is gravitationally sweeping up material and carving out a lane in the disk, like a snow plow.

The planet is estimated to be relatively small, at 6 to 28 times more massive than Earth. Its wide orbit means it is moving slowly around its host star. If the suspected planet were orbiting in our solar system, it would be roughly twice Pluto’s distance from the sun.

Planets are thought to form over tens of millions of years. The buildup is slow, but persistent as a budding planet picks up dust, rocks, and gas from the protoplanetary disk. A planet 7.5 billion miles from its star should take more than 200 times longer to form than Jupiter did at its distance from the sun because of its much slower orbital speed and the deficiency of material in the disk. Jupiter is 500 million miles from the sun and it formed in about 10 million years.

TW Hydrae is only 8 million years old, making it an unlikely star to host a planet, according to this theory. There has not been enough time for a planet to grow through the slow accumulation of smaller debris. Complicating the story further is that TW Hydrae is only 55 percent as massive as our sun.
“It’s so intriguing to see a system like this,” said John Debes of the Space Telescope Science Institute in Baltimore, Md. Debes leads a research team that identified the gap. “This is the lowest-mass star for which we’ve observed a gap so far out.”

An alternative planet-formation theory suggests that a piece of the disk becomes gravitationally unstable and collapses on itself. In this scenario, a planet could form more quickly, in just a few thousand years.
“If we can actually confirm that there’s a planet there, we can connect its characteristics to measurements of the gap properties,” Debes said. “That might add to planet formation theories as to how you can actually form a planet very far out.”

The TW Hydrae disk also lacks large dust grains in its outer regions. Observations from the Atacama Large Millimeter Array in Chile show dust grains roughly the size of a grain of sand are not present beyond about 5.5 billion miles from the star, just short of the gap.

“Typically, you need pebbles before you can have a planet. So, if there is a planet and there is no dust larger than a grain of sand farther out, that would be a huge challenge to traditional planet formation models,” Debes said.

The team used Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS) to observe the star in near-infrared light. The researchers then compared the NICMOS images with archival Hubble data and optical and spectroscopic observations from Hubble’s Space Telescope Imaging Spectrograph (STIS). Debes said researchers see the gap at all wavelengths, which indicates it is a structural feature and not an illusion caused by the instruments or scattered light.

The team’s paper will appear online June 14 in The Astrophysical Journal.




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


 
 

 

Headlines April 1, 2015

News: Iranian aircraft buzzed U.S. Navy helo in Persian Gulf - An Iranian aircraft buzzed a Navy helicopter operating in the Persian Gulf earlier this month, a U.S. military official said March 31. Active duty suicides up in 2014 - Suicides among active duty members of the military increased in 2014, though reservists and members of the...
 
 

News Briefs April 1, 2015

Germany, France, Italy plan to develop military drones Germany and France plan to work together with Italy to develop military surveillance drones that could also carry weapons. French President Francois Hollande said after meeting German Chancellor Angela Merkel March 31 that it is important for Europe to be independent in both manufacturing drones and in...
 
 
Northrop Grumman photograph

AirRobot, Northrop Grumman Remotec sign distribution agreement for unmanned aerial systems

Northrop Grumman photograph An AirRobot unmanned aerial system flies at Fort Benning, Ga.. Northrop Grumman Remotec is the sole reseller of the systems to law enforcement and first responders under a distribution agreement sign...
 

 

Raytheon awarded $528 million AMRAAM contract

Raytheon has been awarded a $528,797,459 fixed-price incentive, firm target contract modification for Advanced Medium Range Air-to-Air Missiles. Raytheon will provide AMRAAM Lot 29 missiles and other AMRAAM system items. This contract involves foreign military sales. Work will be performed in Tucson and is expected to be complete by January 2018. This award was booked...
 
 

Raytheon, DRS team for Army’s third Generation IFLIR B-Kit

Building on their combined platform integration experience, Raytheon and DRS Technologies have entered into a teaming agreement for the U.S. Army’s 3rd Generation Improved Forward Looking Infrared program B-Kit “Raytheon and DRS have teamed to provide an IFLIR solution that provides our military supremacy in reconnaissance, surveillance and target acquisition,” said Dr. Taylor...
 
 

U.S. Air Force awards Raytheon $91.5 million for MALD-J

Raytheon Company received a $91.5 million U.S. Air Force contract modification award for the Miniature Air Launched Decoy Jammer missile. The contract modification is for Lot 8. Work will be performed in Tucson and is expected to be complete by June 2017. This award was booked in the first quarter 2015. MALDÆ is a state-of-the-art,...
 




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>