This artist's illustration shows a
planetary disk (left) that weighs the equivalent of 50 Jupiter-mass
planets. Image credit: NASA/JPL-Caltech
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This artist's concept illustrates the
planet-forming disk around TW Hydrae, located about 175 light-years away
in the Hydra, or Sea Serpent, constellation. Image credit:
NASA/JPL-Caltech
› Full image and caption
› Full image and caption
Download Image
› Full Size
PASADENA, Calif. -- A star thought to have passed the age at which it
can form planets may, in fact, be creating new worlds. The disk of
material surrounding the surprising star called TW Hydrae may be massive
enough to make even more planets than we have in our own solar system.
The findings were made using the European Space Agency's Herschel Space Telescope, a mission in which NASA is a participant.
At roughly 10 million years old and 176 light years away, TW Hydrae is
relatively close to Earth by astronomical standards. Its planet-forming
disk has been well studied. TW Hydrae is relatively young but, in
theory, it is past the age at which giant plants already may have
formed.
"We didn't expect to see so much gas around this star," said Edwin
Bergin of the University of Michigan in Ann Arbor. Bergin led the new
study appearing in the journal Nature. "Typically stars of this age have
cleared out their surrounding material, but this star still has enough
mass to make the equivalent of 50 Jupiters," Bergin said.
In addition to revealing the peculiar state of the star, the findings
also demonstrate a new, more precise method for weighing planet-forming
disks. Previous techniques for assessing the mass were indirect and
uncertain. The new method can directly probe the gas that typically goes
into making planets.
Planets are born out of material swirling around young stars, and the
mass of this material is a key factor controlling their formation.
Astronomers did not know before the new study whether the disk around TW
Hydrae contained enough material to form new planets similar to our
own.
"Before, we had to use a proxy to guess the gas quantity in the
planet-forming disks," said Paul Goldsmith, the NASA project scientist
for Herschel at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
"This is another example of Herschel's versatility and sensitivity
yielding important new results about star and planet formation."
Using Herschel, scientists were able to take a fresh look at the disk
with the space telescope to analyze light coming from TW Hydrae and pick
out the spectral signature of a gas called hydrogen deuteride. Simple
hydrogen molecules are the main gas component of planets, but they emit
light at wavelengths too short to be detected by Herschel. Gas molecules
containing deuterium, a heavier version of hydrogen, emit light at
longer, far-infrared wavelengths that Herschel is equipped to see. This
enabled astronomers to measure the levels of hydrogen deuteride and
obtain the weight of the disk with the highest precision yet.
"Knowing the mass of a planet-forming disk is crucial to understanding
how and when planets take shape around other stars," said Glenn
Wahlgren, Herschel program scientist at NASA Headquarters in Washington.
Whether TW Hydrae's large disk will lead to an exotic planetary system
with larger and more numerous planets than ours remains to be seen, but
the new information helps define the range of possible planet scenarios.
"The new results are another important step in understanding the
diversity of planetary systems in our universe," said Bergin. "We are
now observing systems with massive Jupiters, super-Earths, and many
Neptune-like worlds. By weighing systems at their birth, we gain insight
into how our own solar system formed with just one of many possible
planetary configurations."
Herschel is a European Space Agency (ESA) cornerstone mission, with
science instruments provided by a consortium of European institutes and
with important participation by NASA. NASA's Herschel Project Office is
based at JPL, which contributed mission-enabling technology for two of
Herschel's three science instruments. NASA's Herschel Science Center,
part of the Infrared Processing and Analysis Center at the California
Institute of Technology (Caltech) in Pasadena, supports the United
States astronomical community. Caltech manages JPL for NASA.
More information is online at
and
Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov
J.D. Harrington 202-358-5241
Headquarters, Washington
j.d.harrington@nasa.gov
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov
J.D. Harrington 202-358-5241
Headquarters, Washington
j.d.harrington@nasa.gov
NASA
Guillermo Gonzalo Sánchez Achutegui
ayabaca@gmail.com
ayabaca@hotmail.com
ayabaca@yahoo.com
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