The two images at top reveal debris disks around
young stars uncovered in archival images taken by NASA’s Hubble Space Telescope.
The illustration beneath each image depicts the orientation of the debris
disks.
Image Credit:
NASA/ESA, R. Soummer, Ann Feild
(STScI)
Astronomers using NASA's Hubble Space Telescope have applied a new image
processing technique to obtain near-infrared scattered light photos of five
disks observed around young stars in the Mikulski Archive for Space Telescopes
database. These disks are telltale evidence for newly formed planets.
If astronomers initially miss something in their review of data, they can
make new discoveries by revisiting earlier data with new image processing
techniques, thanks to the wealth of information stored in the Hubble data
archive. This is what Rémi Soummer, of the Space Telescope Science Institute
(STScI) in Baltimore, Md., and his team recently did while on a hunt for hidden
Hubble treasures.
The stars in question initially were targeted with Hubble's Near Infrared
Camera and Multi-Object Spectrometer (NICMOS) based on unusual heat signatures
obtained from NASA's Spitzer Space Telescope and the Infrared Astronomical
Satellite that flew in 1983. The previous data provided interesting clues that
dusty disks could exist around these stars. Small dust particles in the disks
might scatter light and therefore make the disks visible. But when Hubble first
viewed the stars between 1999 and 2006, no disks were detected in the NICMOS
pictures.
Recently, with improvements in image processing, including algorithms used
for face-recognition software, Soummer and his team reanalyzed the archived
images. This time, they could unequivocally see the debris disks and even
determine their shapes.
The NICMOS instrument, which began collecting data in 1997, has been so
cutting-edge that ground-based technology only now is beginning to match its
power. Because Hubble has been in operation for almost 24 years, it provides a
long baseline of high-quality archival observations.
"Now, with such new technologies in image processing, we can go back to the
archive and conduct research more precisely than previously possible with NICMOS
data," said Dean Hines of STScI.
"These findings increase the number of debris disks seen in scattered light
from 18 to 23. By significantly adding to the known population and by showing
the variety of shapes in these new disks, Hubble can help astronomers learn more
about how planetary systems form and evolve," said Soummer.
The dust in the disks is hypothesized to be produced by collisions between
small planetary bodies such as asteroids. The debris disks are composed of dust
particles formed from these grinding collisions. The tiniest particles are
constantly blown outward by radiation pressure from the star. This means they
must be replenished continuously though more collisions. This game of bumper
cars was common in the solar system 4.5 billion years ago. Earth's moon and the
satellite system around Pluto are considered to be collisional byproducts.
"One star that is particularly interesting is HD 141943," said Christine
Chen, debris disk expert and team member. "It is an exact twin of our sun during
the epoch of terrestrial planet formation in our own solar system."
Hubble found the star exhibits an asymmetrical, edge-on disk. This asymmetry
could be evidence the disk is being gravitationally sculpted by the tug of one
or more unseen planets.
"Being able to see these disks now also has let us plan further observations
to study them in even more detail using other Hubble instruments and large
telescopes on the ground," added Marshall Perrin of STScI.
"We also are working to implement the same techniques as a standard
processing method for NASA's upcoming James Webb Space Telescope," said STScI
teammate Laurent Pueyo. "These disks will also be prime targets for the Webb
telescope."
Soummer's team has just begun its work. They next will search for structures
in the disks that suggest the presence of planets.
The Hubble Space Telescope is a project of international cooperation between
NASA and the European Space Agency. NASA's Goddard Space Flight Center in
Greenbelt, Md., manages the telescope. STScI in Baltimore conducts Hubble
science operations. STScI is operated for NASA by the Association of
Universities for Research in Astronomy, Inc., in Washington.
For images and more information about Hubble, visit:
NASA
Guillermo Gonzalo Sánchez Achutegui
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