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SOFIA Reveals How the Swan Nebula Hatched One of the brightest and most massive star-forming regions in
our galaxy, the Omega, or Swan, Nebula, came to resemble the shape resembling a
swan's neck we see today only relatively recently. New observations reveal that
its regions formed separately over multiple eras of star birth. The new image
from the Stratospheric
Observatory for Infrared Astronomy, or SOFIA, is helping scientists chronicle
the history and evolution of this well-studied nebula.
"The
present-day nebula holds the secrets that reveal its past; we just need to be
able to uncover them," said Wanggi Lim, a Universities Space Research Association scientist at
the SOFIA Science Center at NASA's Ames Research Center in California's Silicon
Valley. "SOFIA lets us do this, so we can understand why the nebula looks
the way it does today."
Uncovering the
nebula's secrets is no simple
task. It's located more than 5,000 light-years away in the constellation
Sagittarius. Its center is filled with more than 100 of the galaxy's most
massive young stars. These stars may be many times the size of our Sun, but the
youngest generations are forming deep in cocoons of dust and gas, where they are
very difficult to see, even with space telescopes. Because the central region glows very
brightly, the detectors on space telescopes were saturated at the wavelengths
SOFIA studied, similar to an overexposed photo.
SOFIA's
infrared camera called FORCAST, the Faint Object Infrared Camera for the SOFIA
Telescope, however, can pierce through these cocoons.
The new view
reveals nine protostars, areas where the nebula's clouds are collapsing and
creating the first step in the birth of stars, that had not been seen before.
Additionally, the team calculated the ages of the nebula's different regions.
They found that portions of the swan-like shape were not all created at the
same time, but took shape over multiple eras of star formation.
The central
region is the oldest, most evolved and likely formed first. Next, the northern
area formed, while the southern region is the youngest. Even though the
northern area is older than the southern region, the radiation and stellar
winds from previous generations of stars has disturbed the material there,
preventing it from collapsing to form the next generation.
"This is
the most detailed view of the nebula we have ever had at these wavelengths," said Jim De Buizer, a senior scientist also at the SOFIA
Science Center. "It's the first time we can see some of its youngest,
massive stars and start to truly understand how it evolved into the iconic
nebula we see today."
Massive stars, like those in the Swan Nebula, release so much
energy that they can change the evolution of entire galaxies. But less than 1% of
all stars are this enormous, so astronomers know very little about them. Previous observations of this nebula
with space telescopes studied different wavelengths of infrared light, which did
not reveal the details SOFIA detected.
SOFIA's image
shows gas in blue as it's heated by massive stars located near the center, and
dust in green that is warmed both by existing massive stars and nearby newborn
stars. The newly-detected protostars are located primarily in the southern areas.
The red areas near the edge represent cold dust that was detected by the
Herschel Space Telescope, while the white star field was detected by the
Spitzer Space Telescope.
The Spitzer
Space Telescope will be decommissioned on Jan. 30, 2020, after operating for
more than 16 years. SOFIA continues exploring the infrared universe, building
on Spitzer's legacy. SOFIA
studies wavelengths of mid- and far-infrared light with high resolution that
are not accessible to other telescopes, helping scientists understand star and planet formation, the
role magnetic fields play in
shaping our universe, and the chemical evolution of galaxies.
SOFIA, the Stratospheric Observatory for Infrared Astronomy,
is a Boeing 747SP jetliner modified to carry a 106-inch diameter telescope. It
is a joint project of NASA and the German Aerospace Center (DLR). NASA's Ames
Research Center in California's Silicon Valley manages the SOFIA program,
science and mission operations in cooperation with the Universities Space
Research Association headquartered in Columbia, Maryland, and the German SOFIA
Institute (DSI) at the University of Stuttgart. The aircraft is maintained and
operated from NASA's Armstrong Flight Research Center Building 703, in
Palmdale, California.
JPL manages the Spitzer Space Telescope mission for NASA's
Science Mission Directorate in Washington. Science operations are conducted at
the Spitzer Science Center at Caltech in Pasadena, California. Space operations
are based at Lockheed Martin Space in Littleton, Colorado. Data are archived at
the Infrared Science Archive housed at IPAC at Caltech. Caltech manages JPL for
NASA.
Herschel is a European Space Agency mission, with science
instruments provided by consortia of European institutes and with important
participation by NASA. While the observatory stopped making science
observations in April 2013, after running out of liquid coolant as expected,
scientists continue to analyze its data. NASA's Herschel Project Office is
based at NASA's Jet Propulsion Laboratory in Pasadena. JPL contributed
mission-enabling technology for two of Herschel's three science instruments.
The NASA Herschel Science Center, part of IPAC, supports the U.S. astronomical
community. Caltech manages JPL for NASA.
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