Chuck Bednar for redOrbit.com – @BednarChuck
A newly discovered pulsar has the widest orbit ever discovered around a neutron star and is part of a rare double neutron star system, and could help astronomers gain new insight as to how such systems form and evolve, the National Radio Astronomy Observatory (NRAO) has announced.
Perhaps more impressively, the discovery (reported in a paper scheduled for publication in an upcoming edition of The Astrophysical Journal) was made by a pair of high school students who were analyzing data from the Robert C. Byrd Green Bank Telescope (GBT) in West Virginia.
Data from the 100-meter Robert C. Byrd Green Bank Telescope revealed the telltale signal of a previously unknown pulsar, which was determined to have the widest orbit ever observed around a companion neutron star. (Credit: NRAO/AUI/NSF)
Pulsars, the researchers explained, are rapidly spinning neutron stars, the superdense remains of massive stars that have exploded as supernovas. As it spins, a pulsar emits radio waves from the poles of its magnetic field. Those waves travel across space, and they can be captured by a radio telescope as they sweep across the Earth.
Joe Swiggum, a graduate student in physics and astronomy at West Virginia University and lead author of the study, said that pulsars “are some of the most extreme objects in the universe,” and that the students’ findings show “one of these objects in a really unique set of circumstances.”
Only one out of every 10 identified pulsars are part of a binary system, and most of those can be found in orbit around ancient white dwarf companion stars, the researchers explained. Just a few of them orbit other neutron stars or main sequence stars, and astronomers believe that this is due to the process through which pulsars and other types of neutron stars form.
A tale of two students
Near the end of its normal life, a massive star’s explosion can be “one-sided,” imparting a “kick” to the remaining stellar core and causing the resulting neutron star to be thrown through space, the study authors said. Combined with the loss of mass resulting from a supernova explosion, the phenomenon makes it unlikely that such stars would remain gravitationally locked together.
The pulsar featured in the new study was officially designated as PSR J1930-1852 and was first discovered by Cecilia McGough, who was a student at Strasburg High School in Virginia at the time, and De’Shang Ray, then a student at Baltimore’s Paul Laurence Dunbar High School.
The students were taking part in a National Science Foundation-funded summer Pulsar Search Collaboratory (PSC) workshop in which they analyzed pulsar survey data collected by the GBT. Those who identify strong pulsar candidates are then invited to Green Bank, where they work alongside astronomers to confirm their discoveries.
Based on the differences in spin frequency between the original detection of the pulsar and the follow-up observations, the researchers found that PSR J1930-1852 was part of a binary system. They eventually struggled to find the companion, then eventually discovered that it was another neutron star, and that the duo had widest separation ever observed in a double neutron star system, and that J1930-1852 orbits its companion just once every 45 days.
It’s orbital path, which is about 52 million kilometers, is “more than twice as large as that of any previously known double neutron star system,” Swiggum said. “[Its] parameters give us valuable clues about how a system like this could have formed. Discoveries of outlier systems like J1930-1852 give us a clearer picture of the full range of possibilities in binary evolution.”
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