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| Messier 82, seen in radio frequencies by the Karl G. Jansky Very Large Array. |
Looking back at the science news released by the National Radio
Astronomy Observatory (NRAO) in 2014, the staff scientists at NRAO
selected what they believe are the top 10 stories based on both
scientific impact and public interest.
"These 'top ten' are just a small sampling of the myriad ways in
which the state-of-the-art NRAO facilities are enabling forefront
research by the astronomical community," said NRAO Chief Scientist Chris
Carilli. "Using new telescopes, instrumentation, and techniques,
facilitated by the NRAO, U.S. and international astronomers are
addressing the most pressing problems in planet, star, and galaxy
formation, fundamental physics and cosmology, and astrochemistry and
biology, while finding some real surprises along the way!"
#10 Image Release: Starbursting in the Galaxy M82
A new radio image, made with the Karl G. Jansky Very Large Array
(VLA), reveals fresh information about the central 5200 light-years of
the starbursting galaxy M82. The radio emission seen in the image is
produced by ionized gas and by fast-moving electrons interacting with
the interstellar magnetic field. The bright dots are a mix of
star-forming regions and supernova remnants, the debris from stellar
explosions; analysis of the VLA data tells scientists which of these are
which. Scientists also are studying the faint, wispy features, many of
which were previously unseen, to investigate their relationship with
this galaxy's starburst-driven superwind.
#9 Remarkable White Dwarf Star Possibly Coldest, Dimmest Ever Detected
A team of astronomers has identified possibly the coldest, faintest
white dwarf star ever detected. This ancient stellar remnant is so cool
that its carbon has crystallized, forming -- in effect -- an Earth-size
diamond in space. The researchers found this stellar gem using the
National Radio Astronomy Observatory's (NRAO) Green Bank Telescope (GBT)
and Very Long Baseline Array (VLBA), as well as other observatories.
Other such stars have been identified and they are theoretically not
that rare, but with a low intrinsic brightness, they can be deucedly
difficult to detect. Its fortuitous location in a binary system with a
neutron star enabled the team to identify this one.
#8 Newly Identified Galactic Supercluster Is Home to the Milky Way
Astronomers using the National Science Foundation's Green Bank
Telescope (GBT) -- among other telescopes -- have determined that our
own Milky Way galaxy is part of a newly identified ginormous
supercluster of galaxies, which they have dubbed "Laniakea," which means
"immense heaven" in Hawaiian. This discovery clarifies the boundaries
of our galactic neighborhood and establishes previously unrecognized
linkages among various galaxy clusters in the local Universe. By using
the GBT and other radio telescopes to map the velocities of galaxies
throughout our local Universe, the team was able to define the region of
space where each supercluster dominates.
#7 Planet-forming Lifeline Discovered in a Binary Star System
Scientists using the Atacama Large Millimeter/submillimeter Array
(ALMA) have detected a streamer of dust and gas flowing from a massive
outer disk toward the inner reaches of a binary star system known as GG
Tau-A. This newly discovered feature may be responsible for sustaining a
second, smaller disk of planet-forming material that otherwise would
have disappeared long ago. Like a wheel in a wheel, GG Tau-A contains a
large, outer disk encircling the entire system as well as an inner disk
around the main central star. While observing these structures with
ALMA, the team made the exciting discovery of gas clumps in the region
between the two disks. The new observations suggest that material is
being transferred from the outer disk to the inner disk, creating a
sustaining lifeline between the two.
#6 Orion Rocks! Pebble-size Particles May Kick Start Planet Formation
Astronomers using the National Science Foundation's (NSF) Green Bank
Telescope (GBT) have discovered that filaments of star-forming gas near
the Orion Nebula may be brimming with pebble-size particles -- planetary
building blocks 100 to 1,000 times larger than the dust grains
typically found around protostars. If confirmed, these dense ribbons of
rocky material may well represent a new, mid-size class of interstellar
particles that could help jump-start planet formation. Though incredibly
small compared to even the most modest of asteroids, dust grains on the
order of a few millimeters to a centimeter are incredibly large for
such young star-forming regions.
#5 Swarms of Pluto-size Objects Kick Up Dust around Adolescent Sun-Like Star
Astronomers using the Atacama Large Millimeter/submillimeter Array
(ALMA) may have detected the dusty hallmarks of an entire family of
Pluto-size objects swarming around an adolescent version of our own Sun.
By making detailed observations of the protoplanetary disk surrounding
the star known as HD 107146, the astronomers detected an unexpected
increase in the concentration of millimeter-size dust grains in the
disk's outer reaches. This surprising increase, which begins remarkably
far -- about 13 billion kilometers -- from the host star, may be the
result of Pluto-size planetesimals stirring up the region, causing
smaller objects to collide and blast themselves apart.
#4 Pulsar in a Stellar Triple System Makes Unique Gravitational Laboratory
Astronomers using the National Science Foundation's Green Bank
Telescope (GBT) have discovered a unique stellar system of two white
dwarf stars and a superdense neutron star, all packed within a space
smaller than Earth's orbit around the Sun. The closeness of the stars,
combined with their nature, has allowed the scientists to make the best
measurements yet of the complex gravitational interactions in such a
system. In addition, detailed studies of this system may provide a key
clue for resolving one of the principal outstanding problems of
fundamental physics -- the true nature of gravity.
#3 New Radar Images Uncover Remarkable Features below the Surface of the Moon: Sea of Serenity and Aristillus Crater
New images of Earth's Moon reveal more than can be seen with the
naked eye, thanks to the combined efforts of the two largest radio
telescopes of their kind -- the National Radio Astronomy Observatory's
Green Bank Telescope (GBT) in West Virginia and the Arecibo Observatory
in Puerto Rico. To make these images, radar signals beamed from
Arecibo's powerful transmitter penetrated far below the Moon's dusty
surface. The signals then rebounded back and were picked up by the
sensitive receivers on the GBT. This observing technique, known as
bistatic radar, has been used to study many objects in our Solar System,
including asteroids and other planets.
#2 Radio Telescopes Settle Controversy over Distance to Pleiades
Astronomers have used a worldwide network of radio telescopes to
resolve a controversy over the distance to a famous star cluster -- a
controversy that posed a potential challenge to scientists' basic
understanding of how stars form and evolve. The new work shows that the
measurement made by a cosmic-mapping research satellite was wrong. The
result of their work is a distance to the Pleiades of 443 light-years,
accurate, the astronomers said, to within one percent. This is the most
accurate and precise measurement yet made of the Pleiades distance.
#1 Birth of Planets Revealed in Astonishing Detail in ALMA's 'Best Image Ever'
Astronomers have captured the best image ever of planet formation
around an infant star as part of the testing and verification process
for the Atacama Large Millimeter/submillimeter Array's (ALMA) new
high-resolution capabilities. This revolutionary new image reveals in
astonishing detail the planet-forming disk surrounding HL Tau, a
Sun-like star located approximately 450 light-years from Earth in the
constellation Taurus. ALMA uncovered never-before-seen features in this
system, including multiple concentric rings separated by clearly defined
gaps. These structures suggest that planet formation is already well
underway around this remarkably young star.
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