J.D. Harrington
Headquarters, Washington
202-358-5241
j.d.harrington@nasa.gov
Whitney Clavin
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-4673
whitney.clavin@jpl.nasa.gov
RELEASE: 13-036
HERSCHEL FINDS STAR POSSIBLY MAKING PLANETS PAST ITS PRIME
WASHINGTON -- 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 (JPL) in
Pasadena, Calif. "This is another example of Herschel's versatility
and sensitivity yielding important new results about star and planet
formation."
Using Herschel, they 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.
For NASA'S Herschel website, visit:
http://www.nasa.gov/herschel For ESA'S Herschel website, visit:
http://www.esa.int/SPECIALS/Herschel/index.html
