Here come the pulsars! On Thursday, NASA announced the discovery of 10 new pulsars, ultra-dense, ultra-fast-spinning dead stars that emit powerful beams, or “pulses,” of electromagnetic radiation. That brings the total number of pulsars discovered by the agency’s Fermi gamma-ray space telescope to 100. Better yet, one of the new dead stars discovered was the youngest of a special kind of pulsar – the millisecond pulsar- discovered yet.
“What this means is that we’re looking at the tip of the iceberg of a totally new class of short-lived pulsar,” said Paulo Freire, an astrophysicist at the Max Planck Institute for Radio Astronomy in Bonn, Germany, in a conference call Thursday announcing the discoveries.
To commemorate the finds, NASA released a new interactive all-sky map allowing users to see the 100 dead stars using the Fermi telescope’s gamma-ray view. The map, which requires Flash, is viewable here.
All of the 100 pulsars were found because they emit gamma rays, the form of electromagnetic radiation with the highest-energy level, 100,000 times more powerful than visible light.
A pulsar is formed when a giant star four to eight times the size of Earth’s Sun runs out of its nuclear fuel and goes supernova, collapsing in on itself to form an object about the size of Manhattan with a density in the order of billions of tons per inch.
As such, they’re the closest thing to a black hole that scientists can observe directly. (Black holes can’t be seen directly because they suck up all visible light, scientists have to rely on nearby material getting sucked in to see them).
Located 26,000 light years away in the direction of the constellation Sagittarius (close to the Milky Way’s center), the youngest millisecond pulsar, the decidedly unappealingly-named J1823-3021A, is a one of a special class of dead stars with an incredibly fast rotation.
This pulsar spins at 11,000 rotations per minute, causing it to spit off gamma rays and other radiation in installments of 183.8 pulses ever second, a rotation period of 5.44 milliseconds. Millisecond pulsars are those with rotation periods under 25 milliseconds.
The newly-discovered young millisecond pulsar is thought to be less than 25 million years old, while other millisecond pulsars generally tend to be “in the order of billions of years old,” according to Freire.
“It’s amazing that all of the gamma rays we see from this cluster are coming from a single object,” Friere said in a statement published online. “It must have formed recently based on how rapidly it’s emitting energy. It’s a bit like finding a screaming baby in a quiet retirement home.”
By comparison, none of the other nine pulsars discovered in other clusters are millisecond pulsars, with slow pulse rates between 3 pulses per second and 12 pulses per second. They’re also even younger than the baby millisecond star, between 200,000 and 3.1 million years sold.
Scientists think millisecond pulsars achieve their high rotation speeds and pulse rates because they are one half of binary star systems, that is, each millisecond pulsar is only found next to another, normal star that is still “alive,” one that hasn’t gone supernova yet. The gravity fields of the two stars overlap and the normal star is able to “feed” the dead millisecond star with currents of gravitationally transferred gas.
The new baby pulsar is described in a paper published in the November 3 issue of the journal Science (paywall). It’s also shown-off in a new simulation video from NASA here:
In addition, scientists also published a paper in the Astrophysical Journal the discovery of the other nine pulsars located throughout the universe. These were even more difficult to find than the young millisecond pulsar because they were so faint, with Fermi only detecting one gamma ray for every 100,000 rotations of some of them. Only one of them emitted radio waves picked up on Earth.
Before the telescope was launched in 2008, NASA knew of other pulsars, but only thought seven of them emitted gamma rays. At the time, NASA used radio telescopes to try and locate pulsars, with some initial success, as pulsars also emit radio waves.
But Fermi was a huge boost because radio waves represent only a few parts per million of a pulsar’s total power, whereas gamma rays account for 10 percent or more, making a gamma ray telescope more suited to the task, as NASA explained back in 2009, when Fermi data uncovered 12 new pulsars.
NASA notes that some other pulsars Fermi has discovered in its three years of surveying with Fermi spin even faster than the young new one, upwards of 43,000 revolutions per minute. See them all here.
Correction: This article originally referred to the pulsar as the “youngest pulsar yet discovered.” In fact, it is only the youngest millisecond pulsar yet discovered, as a reader notified TPM. The article has since been corrected. We regret the error.
