Heart shape for the stars. My astronomy work.
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Astronomers have detected a radio signal from a distant galaxy that flashes regularly for up to three seconds.
More than a billion light-years away, the signal is called FRB 20191221A and is classified as a “fast radio burst” – a radio pulse. About 1,000 times longer than most FRBs, FRB 20191221A is now the longest-lasting and most regular radio signal known in the entire night sky.
It was discovered using the CHIME radio telescope in British Columbia, Canada, which discovered over 500 FRBs in its first year of operation. The results are published in Nature.
Scientists believe the radio signal may be coming from a neutron star – what remains of the collapsed core of a giant star after it has exploded as a supernova. Neutron stars spin rapidly.
Although the origin of FRBs is mysterious, we hope that the frequency of each one and how they vary with distance from us can tell scientists the exact rate at which the universe is expanding. The first FRB was discovered in 2007.
FRB 20191221A was first detected on December 21, 2019. “It was unusual,” said Daniele Micilli, a postdoctoral fellow at MIT’s Kavli Institute for Astrophysics and Space Studies. “Not only was it very long, about three seconds long, but there were periodic spikes that were remarkably precise, emitting every fraction of a second – boom, boom, boom – like a heartbeat.”
Artwork illustrating a fast radio signal. Magnetars are types of neutron stars that have extremely … [+] powerful magnetic fields trillions of times stronger than Earth’s own field and even more powerful than ordinary neutron stars. Recently, astronomers have suggested that asteroids may be orbiting some of these objects, causing the emission of Fast Radio Bursts (FRBs). The idea is that asteroids orbiting in the magnetar’s wind – a stream of fast particles emanating from its surface – form a wake in the wind, which causes an electric current to be generated around the wake. When the magnetar wind crosses the track, a magnetic disturbance is created that generates an extremely intense, narrow beam of radio energy. In 2020, astronomers detected the first FRB from a magnetar – called SGR 1935+2154 – located in our own galaxy. The whole event was over in a split second.
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So what could be the source of FRB 20191221A?
“There aren’t many things in the universe that emit strictly periodic signals,” Micilli said. “Examples we know of in our own galaxy are radio pulsars and magnetars, which rotate and produce a beacon-like beam. And we think this new signal could be a magnetar or pulsar on steroids.
Types of Neutron Stars A pulsar is a neutron star that emits beams of radio waves and appears to pulsate as the star rotates, while a magnetar has extreme magnetic fields. The FRB 20191221A signal is a million times brighter than the pulsars and magnetars in the Milky Way.
“From the properties of this new signal, we can tell that there is a cloud of plasma around this source that must be extremely turbulent,” Micilli said. “Future telescopes promise to detect thousands of FRBs per month, and at this point we may detect many more of these periodic signals.”
Wishing you clear skies and wide-open eyes.
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