Telescope Team Discovers 10 Strange and Exotic Pulsars

At the center of our Milky Way galaxy, in the constellation Sagittarius, astronomers have discovered 10 monstrous neutron stars. These peculiar stars, called pulsars, reside together in the globular cluster Terzan 5, a hotbed populated by hundreds of thousands of stars of different types.

The article is published in the journal Astronomy and astrophysics.

Pulsars are millions (or even billions) of times denser than other stars and spin rapidly, emitting bright pulses of light thanks to their powerful magnetic fields, making them a beacon for astronomers. In one of the most densely populated places in our Milky Way, many of Terzan 5’s pulsars have evolved into bizarre and eccentric shapes.

Astronomers already knew that 39 pulsars inhabit Terzan 5. Thanks to the teamwork of the National Science Foundation’s Green Bank Telescope (NSF GBT) in the United States and the MeerKAT telescope of the South African Radio Astronomy Observatory, 10 more pulsars have been added to this number.

“It’s very unusual to find new exotic pulsars. But what’s really exciting is the sheer variety of these strange pulsars within a single cluster,” said Scott Ransom, a scientist at the National Science Foundation’s National Radio Astronomy Observatory (NSF NRAO) in the United States. The discoveries were made by an international team of astronomers from NSF NRAO, the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) (AEI), and the Max Planck Institute for Radio Astronomy.

The Meerkat telescope was able to determine the approximate location of each pulsar by tracking and timing the speed of their rotation, compared to twenty years of observations of Terzan 5 taken by the NSF GBT, which revealed the bizarre and eccentric details of these stars.

“Without the NSF Green Bank Telescope archive, we would not have been able to characterize these pulsars and understand their astrophysics,” Ransom adds. The archived data from the NSF GBT telescope allowed astronomers to pinpoint the positions of pulsars in the sky, measure their specific motions, and see how their orbits have evolved over time.

Among the discoveries, astronomers observed two neutron stars likely being pulled into each other’s orbit as a binary system. Of the 3,600 known pulsars in the galaxy, only 20 have been identified as double neutron star binaries.

When pulsars form pairs in binaries, the gravitational pull of one toward the other can steal matter and energy, causing one of them to spin even faster and become a millisecond pulsar. This pair could break records, with a new contender for the title of fastest-spinning pulsar in a double neutron star system, and the longest orbit of its kind. The current record holder for the fastest-spinning pulsar already resides in Terzan 5. Only future observations will reveal the truth.

Astronomers have also observed three new rare binary “spider” pulsar systems (in addition to the five already known in the cluster) called Redbacks or Black Widows, depending on the types of companion stars they have. A companion star falls into the orbit of a spider pulsar, where a lattice of plasma fills the space between the two (caused by outflows from the companion star due to the pulsar’s energy) slowly dissolving the companion over time.

The discovery of these strange pulsars allows scientists to better understand globular clusters, neutron stars and even test Einstein’s theory of general relativity, while deepening our knowledge of the categories of pulsars. The research team already plans to find even more in Terzan 5, with the support of volunteers.

Citizen scientists who want to share the excitement of this discovery can help with Einstein@Home, a project led by AEI scientists that has already discovered more than 90 new neutron stars.