A team of highly determined high school students discovered a never-before-seen pulsar by painstakingly analyzing data from the National Science Foundation’s (NSF) Robert C. Byrd Green Bank Telescope (GBT). Further observations by astronomers using the GBT revealed that this pulsar has the widest orbit of any around a neutron star and is part of only a handful of double neutron star systems.
This impressive find will help astronomers better understand how binary neutron star systems form and evolve.
Pulsars are rapidly spinning neutron stars, the superdense remains of massive stars that have exploded as supernovas. As a pulsar spins, lighthouse-like beams of radio waves, streaming from the poles of its powerful magnetic field, sweep through space. When one of these beams sweeps across the Earth, radio telescopes can capture the pulse of radio waves.
Starting today at NASA’s Columbia Scientific Balloon Facility in Fort Sumner, New Mexico, space scientists from the University of New Hampshire will attempt to launch a football-field-sized balloon carrying a one-ton instrument payload that will measure gamma rays from the Crab Pulsar – the remains of a 1054 A.D. supernova explosion 6,500 light years from Earth. The measurements, taken 130,000 feet above Earth, could eventually provide a window into the universal, poorly understood process of particle acceleration.
The Gamma Ray Polarimeter Experiment (GRAPE), which was designed and built at the Space Science Center (SSC) within the UNH Institute for the Study of Earth, Oceans, and Space, is an effort to apply a new type of detector technology to the study of celestial gamma rays. The launch is highly dependent on weather and upper atmospheric wind conditions. The launch window closes at the end of this month.
The specific goal of the GRAPE mission is to study the polarization of gamma rays from celestial sources. “Polarized” radiation vibrates in a preferred direction, and the extent of that polarization can provide clues to how the radiation was generated, in essence serving as a probe of the source.
“Up above the world so high, like a diamond in the sky…” A team of astronomers, using multiple telescopes, has identified the coolest, faintest white dwarf star known. White dwarfs are the extremely dense end states of stars like our sun: after their nuclear fuel is exhausted, they collapse from the size of a star (about 1,000,000 miles across) to the size of the Earth (7,000 miles across). This white dwarf, located in the constellation Aquarius, is so cool that its carbon has crystallized—in other words, it’s like a diamond, with a mass similar to that of our sun.
The path to this discovery began when Dr. Jason Boyles, then a graduate student at West Virginia University, identified what astronomers refer to as a millisecond pulsar in this location. Pulsars are spinning neutron stars—the collapsed end state of a star many times more massive than our sun, but only about 20 miles across. Known as PSR J2222-0137, which simply identifies its position in the sky, this pulsar is spinning over 30 times a second. Its orientation is such that as it spins, a beam from its magnetic pole sweeps repeatedly past the earth, giving rise to regular blips of radio waves. (The pulsar is detected only in radio waves, not in visible light.) The observations also revealed that this pulsar is gravitationally bound to a companion star: the two orbit around each other every 2.45 days. It is this companion object that appears to be either another neutron star or, more likely, a remarkably cool white dwarf.
A team of astronomers, including Danai Antonopoulou and Anna Watts from the University of Amsterdam, has discovered that sudden speed jumps in the rotational velocity of pulsars have a minimum size, and that they are caused not by the unpinning and displacement of just one sub-surface superfluid vortex, but by billions. This result is important to our understanding of the behavior of matter under extreme conditions, and has been published this week in the journal Monthly Notices of the Royal Astronomical Society.
Pulsars are rotating neutron stars – remnants of massive stars that end their lives in supernova explosions. They act like cosmic lighthouses whose beams sweep through the Universe. Their rotational velocity decreases in time, but can suddenly increase in rare events called glitches. These glitches are caused by the unpinning and displacement of vortices that connect the crust with the mixture of particles containing superfluid neutrons beneath the crust.
The team of astronomers discovered that the glitches of the Crab Pulsar always involve a decrease in the rotational period of at least 0.055 nanoseconds. The Crab Pulsar was one of the first pulsars to be discovered and has been observed almost daily with the 42-ft Telescope at the Jodrell Bank Observatory over the last 29 years. The huge amount of data makes this object the best choice to study glitches.
Black widow spiders and their Australian cousins, known as redbacks, are notorious for their tainted love, expressed as an unsettling tendency to kill and devour their male partners. Astronomers have noted similar behavior among two rare breeds of binary system that contain rapidly spinning neutron stars, also known as pulsars.
“The essential features of black widow and redback binaries are that they place a normal but very low-mass star in close proximity to a millisecond pulsar, which has disastrous consequences for the star,” said Roger Romani, a member of the Kavli Institute for Particle Astrophysics and Cosmology, an institute run jointly by Stanford and SLAC National Accelerator Laboratory in Menlo Park, Calif. Black widow systems contain stars that are both physically smaller and of much lower mass than those found in redbacks.
So far, astronomers have found at least 18 black widows and nine redbacks within the Milky Way, and additional members of each class have been discovered within the dense globular star clusters that orbit our galaxy.
NASA’s Chandra X-ray Observatory has seen a fast-moving pulsar escaping from a supernova remnant while spewing out a record-breaking jet – the longest of any object in the Milky Way galaxy — of high-energy particles.
The pulsar, a type of neutron star, is known as IGR J11014-6103. IGR J11014-6103’s peculiar behavior can likely be traced back to its birth in the collapse and subsequent explosion of a massive star.
Originally discovered with the European Space Agency satellite INTEGRAL, the pulsar is located about 60 light-years away from the center of the supernova remnant SNR MSH 11-61A in the constellation of Carina. Its implied speed is between 2.5 million and 5 million mph, making it one of the fastest pulsars ever observed.
“We’ve never seen an object that moves this fast and also produces a jet,” said Lucia Pavan of the University of Geneva in Switzerland and lead author of a paper published Tuesday,in the journal Astronomy and Astrophysics. “By comparison, this jet is almost 10 times longer than the distance between the sun and our nearest star.”
Since its launch in 2008, the Fermi satellite has been observing the entire sky in gamma-rays. It has discovered thousands of previously unknown gamma-ray sources, among which are possibly hundreds of yet undiscovered pulsars – compact and rapidly rotating remnants of exploded stars. Identifying these new gamma-ray pulsars, however, is computationally very expensive – wide parameter ranges have to be “scanned” at very high resolution.
“Our innovative solution for the compute intensive search for gamma-ray pulsars is the combination of particularly efficient methods along with the distributed computing power of Einstein@Home,” says Holger Pletsch, Independent Research Group Leader at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI), and lead author of the study. “The volunteers from around the world enable us to deal with the huge computational challenge posed by the Fermi data analysis. In this way, they provide an invaluable service to astronomy,” says Pletsch.