Some stars emit radio waves fairly steadily, while some compact neutron stars flash like beacons in the sky. But others brighten and dim erratically, without any discernible pattern to the outbursts, according to Maura McLaughlin in research published by Nature last week.
The team have discovered a new class of astrophysical objects, which they call rotating radio transients (RRATs). These emit short bursts of radio waves, lasting just 2 to 30 milliseconds, interspersed with 'dark' spells of several minutes to hours. The researchers say that the radio signals from these objects are typically detectable for less than a second in total each day.
The researchers have discovered eleven such objects in a four-year survey conducted to look for transient radio sources of this kind. Although the bright events are so short, they nevertheless show signs of periodicity for ten of the objects, repeating in cycles of 0.4 to 7 seconds. In other words, the objects are rather like lighthouses that are plagued by frequent, random and prolonged power cuts.
What causes these shutdowns? McLaughlin and colleagues aren't sure what RRATs are yet, beyond supposing that they are a kind of rotating neutron star. But they seem to be plentiful: the researchers estimate that there should be many more of them in our Galaxy than there are regularly pulsing neutron stars. It's just that, because they are 'dark' most of the time, they can only be seen by looking hard and long.
Source: Nature
Related stories:
The thousand-ruby galaxy
ESO's Wide Field Imager has captured the intricate swirls of the spiral galaxy Messier 83, a smaller look-alike of our own Milky Way. Shining with the light of billions of stars and the ruby red glow of hydrogen gas, it is a beautiful example of a barred spiral galaxy, whose shape has led to it being nicknamed the Southern Pinwheel.
Einstein was right: Unique stellar system provides 'laboratory' for testing relativity
Researchers at McGill University's Department of Physics – along with colleagues from several countries – have confirmed a long-held prediction of Albert Einstein's theory of general relativity, via observations of a binary-pulsar star system. Their results will be published July 3 in the journal
Science.
Strange star stumps astronomers
An obese oddball of a star has left astronomers wondering how it could have formed. Dr David Champion and his colleagues at CSIRO’s Australia Telescope National Facility publish their findings about the star today in the online journal,
Science Express.
Galaxies Gone Wild
Interacting galaxies are found throughout the Universe, sometimes as dramatic collisions that trigger bursts of star formation, on other occasions as stealthy mergers that result in new galaxies. A series of 59 new images of colliding galaxies has been released from the several terabytes of archived raw images from the NASA/ESA Hubble Space Telescope to mark the 18th anniversary of the telescope’s launch. This is the largest collection of Hubble images ever released to the public simultaneously.
MIT to lead development of new telescopes on moon
NASA has selected a proposal by an MIT-led team to develop plans for an array of radio telescopes on the far side of the moon that would probe the earliest formation of the basic structures of the universe. The agency announced the selection and 18 others related to future observatories on Friday, Feb.15.
Very large array retooling for 21st-century science
An international project to make the world's most productive ground-based telescope 10 times more capable has reached its halfway mark and is on schedule to provide astronomers with an extremely powerful new tool for exploring the Universe. The National Science Foundation's Very Large Array (VLA) radio telescope now has half of its giant, 230-ton dish antennas converted to use new, state-of-the-art digital electronics to replace analog equipment that has served since the facility's construction during the 1970s.
Worldwide effort bringing ALMA telescope into reality
In the thin, dry air of northern Chile's Atacama Desert, at an altitude of 16,500 feet, an amazing new telescope system is taking shape, on schedule to provide the world's astronomers with unprecedented views of the origins of stars, galaxies, and planets. The Atacama Large Millimeter/submillimeter Array (ALMA) will open an entirely new "window" on the Universe, allowing scientists to unravel longstanding and important astronomical mysteries.
Hubble finds strong contender for galaxy distance record
Detailed images from Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS) reveal an infant galaxy, dubbed A1689-zD1, undergoing a firestorm of star birth as it comes out of the dark ages, a time shortly after the Big Bang, but before the first stars completed the reheating of the cold, dark Universe. Images from NASA’s Spitzer Space Telescope’s Infrared Array Camera provided strong additional evidence that it was a young star-forming galaxy in the dark ages.