Top Ten Radio Hits of 2014: NRAO Astronomers Select Most Interesting News Stories of the YearDecember 31, 2014
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.