Featured Research

from universities, journals, and other organizations

Planet-like object found circling a brown dwarf

Date:
April 9, 2010
Source:
Space Telescope Science Institute
Summary:
As our telescopes grow more powerful, astronomers are uncovering objects that defy conventional wisdom. The latest example is the discovery of a planet-like object circling a brown dwarf. It's the right size for a planet, estimated to be 5-10 times the mass of Jupiter. But the object formed in less than 1 million years -- the approximate age of the brown dwarf -- and much faster than the predicted time it takes to build planets according to some theories.

This is a Hubble Space Telescope image of young brown dwarf 2M J044144. It has a companion object at the 8 o'clock position that is estimated to be 5-10 times the mass of Jupiter. In the right panel, the light from the brown dwarf has been subtracted to provide a clearer view of the companion object. The separation of the companion corresponds to 1.4 billion miles at the distance of the Taurus star-forming region, which is only about 1 million years old. The companion may be a very small brown dwarf or a large planet, depending on how it formed. Images were taken with Hubble's Wide Field Planetary Camera 2 to track the motion of the two objects to see if they actually do travel across space together. Additional observations were done with the Gemini North telescope on Mauna Kea, Hawaii.
Credit: NASA, ESA, and K. Todorov and K. Luhman (Penn State University)

As our telescopes grow more powerful, astronomers are uncovering objects that defy conventional wisdom. The latest example is the discovery of a planet-like object circling a brown dwarf. It's the right size for a planet, estimated to be 5-10 times the mass of Jupiter. But the object formed in less than 1 million years -- the approximate age of the brown dwarf -- and much faster than the predicted time it takes to build planets according to some theories.

Kamen Todorov of Penn State University and co-investigators used the keen eyesight of the Hubble Space Telescope and the Gemini Observatory to directly image the companion of the brown dwarf, which was uncovered in a survey of 32 young brown dwarfs in the Taurus star-forming region. Brown dwarfs are objects that typically are tens of times the mass of Jupiter and are too small to sustain nuclear fusion to shine as stars do.

The mystery object orbits the nearby brown dwarf at a separation of approximately 2.25 billion miles (3.6 billion kilometers -- which is between the distances of Saturn and Uranus from the Sun). The team's research is being published in an upcoming issue of The Astrophysical Journal.

There has been a lot of discussion in the context of the Pluto debate over how small an object can be and still be called a planet. This new observation addresses the question at the other end of the size spectrum: How small can an object be and still be a brown dwarf rather than a planet? This new companion is within the range of masses observed for planets around stars -- less than 15 Jupiter masses. But should it be called a planet? The answer is strongly connected to the mechanism by which the companion most likely formed.

There are three possible formation scenarios: Dust in a circumstellar disk slowly agglomerates to form a rocky planet 10 times larger than Earth, which then accumulates a large gaseous envelope; a lump of gas in the disk quickly collapses to form an object the size of a gas giant planet; or, rather than forming in a disk, a companion forms directly from the collapse of the vast cloud of gas and dust in the same manner as a star (or brown dwarf).

If the last scenario is correct, then this discovery demonstrates that planetary-mass bodies can be made through the same mechanism that builds stars. This is the likely solution because the companion is too young to have formed by the first scenario, which is very slow. The second mechanism occurs rapidly, but the disk around the central brown dwarf probably did not contain enough material to make an object with a mass of 5-10 Jupiter masses.

"The most interesting implication of this result is that it shows that the process that makes binary stars extends all the way down to planetary masses. So it appears that nature is able to make planetary-mass companions through two very different mechanisms," says team member Kevin Luhman of the Center for Exoplanets and Habitable Worlds at Penn State University. If the mystery companion formed through cloud collapse and fragmentation, as stellar binary systems do, then it is not a planet by definition because planets build up inside disks.

The mass of the companion is estimated by comparing its brightness to the luminosities predicted by theoretical evolutionary models for objects at various masses for an age of 1 millon years.

Further supporting evidence comes from the presence of a very nearby binary system that contains a small red star and a brown dwarf. Luhman thinks that all four objects may have formed in the same cloud collapse, making this in actuality a quadruple system. "The configuration closely resembles quadruple star systems, suggesting that all of its components formed like stars," says Luhman.


Story Source:

The above story is based on materials provided by Space Telescope Science Institute. Note: Materials may be edited for content and length.


Journal Reference:

  1. K. Todorov, K. L. Luhman, K. K. McLeod. Discovery of a Planetary-mass Companion to a Brown Dwarf in Taurus. The Astrophysical Journal, 2010; 714 (1): L84 DOI: 10.1088/2041-8205/714/1/L84

Cite This Page:

Space Telescope Science Institute. "Planet-like object found circling a brown dwarf." ScienceDaily. ScienceDaily, 9 April 2010. <www.sciencedaily.com/releases/2010/04/100409144354.htm>.
Space Telescope Science Institute. (2010, April 9). Planet-like object found circling a brown dwarf. ScienceDaily. Retrieved July 24, 2014 from www.sciencedaily.com/releases/2010/04/100409144354.htm
Space Telescope Science Institute. "Planet-like object found circling a brown dwarf." ScienceDaily. www.sciencedaily.com/releases/2010/04/100409144354.htm (accessed July 24, 2014).

Share This




More Space & Time News

Thursday, July 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: ISS Cargo Ship Launches in Kazakhstan

Raw: ISS Cargo Ship Launches in Kazakhstan

AP (July 23, 2014) The Progress 56 cargo ship launched from the Baikonur Cosmodrome in Kazakhstan Wednesday. NASA says it will deliver cargo and crew supplies to the International Space Station. (July 23) Video provided by AP
Powered by NewsLook.com
Raw: Cargo Craft Undocks from Space Station

Raw: Cargo Craft Undocks from Space Station

AP (July 22, 2014) A Russian Soyuz cargo-carrying spacecraft undocked from the International Space Station on Monday. The craft is due to undergo about ten days of engineering tests before it burns up in the Earth's atmosphere. (July 22) Video provided by AP
Powered by NewsLook.com
NASA Ceremony Honors Moon Walker Neil Armstrong

NASA Ceremony Honors Moon Walker Neil Armstrong

AP (July 21, 2014) NASA honored one of its most famous astronauts Monday by renaming a historic building at the Kennedy Space Center in Florida. It now bears the name of Neil Armstrong, the first man to walk on the moon. (July 21) Video provided by AP
Powered by NewsLook.com
Neil Armstrong's Post-Apollo 11 Life

Neil Armstrong's Post-Apollo 11 Life

Newsy (July 19, 2014) Neil Armstrong gained international fame after becoming the first man to walk on the moon in 1969. But what was his life like after the historic trip? Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins