Astronomers
say they have directly imaged a giant exoplanet orbiting its parent star. The
announcement comes on the heels of two other reports this month of direct
images of planets beyond our solar system.
The new
infrared image shows the object as a speck of light near the star Beta
Pictoris, which is 70 light-years from Earth, toward the constellation
Pictor.
"We
cannot yet rule out definitively, however, that the candidate companion could
be a foreground or background object," said study team member Gael Chauvin
of Grenoble Observatory in France. "To eliminate this very small
possibility, we will need to make new observations that confirm the nature of
the discovery."
Chauvin and
other French astronomers discovered the candidate planet
using the European Southern Observatory's (ESO) Very Large Telescope. The
possible planet is estimated to weigh about eight times the mass of Jupiter
with an orbit of eight astronomical units (AU) from its star, where one AU is
the average Earth-sun distance.
Astrophysicist
Sara Seager of MIT, who was not involved in the latest discovery, said while
the possibility is exciting, another more convincing image of the object is in
order. "We want to make sure it's moving together with the star,"
Seager said.
Another
image would show whether the star is moving at a different speed relative to
this object and other background objects or if the star and planet are moving
together (which would help to confirm this is indeed a planet).
Astronomers
had thought a planet could be responsible for irregularities seen in the debris
disk, first imaged in 1994, surrounding Beta Pictoris. As a planet treks around
its star, the planet jostles and tugs on pieces of dust and debris, shaping the
disk.
"Beta
Pic has been teasing astronomers for the past two decades with hints of an
orbiting planet," said University of California, Berkeley, astronomer Paul
Kalas, who was not directly involved with the study. Kalas led a team of
astronomers who reported this month the first visible-light snapshot
of a single-planet system around the star Fomalhaut.
The
researchers say the object does explain the warped disk. "The candidate
companion has exactly the mass and distance from its host star needed to
explain all the disk's properties," said team leader Anne-Marie Lagrange
of the Grenoble Observatory.
The team
tried to rule out other non-planet possibilities. For instance, they looked at
images taken by the Hubble
Space Telescope of the system, which would likely reveal background and
foreground objects.
They also
used three independent detection methods to rule out the possibility that the
point source of light was just an artifact of the observing instrument.
"Overall,
this is an exciting discovery that could be verified in just a few weeks time
since Beta Pictoris is a bright star visible during the winter months,"
Kalas told SPACE.com.
Actually,
Lagrange said the planet might not be visible with their instruments currently,
because of the inclination of the orbit and how it is aligned. So from our
perspective on Earth, the planet could travel too close to its star to be
visible.
The
discovery will be detailed in a forthcoming letter to the editor in the journal
Astronomy and Astrophysics.
advertisement
%2C+with+a+disk+of+debris+shown+around+the+star-planet+system.+Credit%3A+ESO%2FA.-M.+Lagrange+et+al.){kind=link}