White dwarf and red dwarf bump together to emit a radio blast every two hours
Artist’s impression of a red dwarf (left) and a white dwarf (center) orbiting each other. The stars’ orbit is so tight that their magnetic fields interact, causing pulses of radio emission every two hours. Image by Daniëlle Futselaar/artsource.nl
An international team of astronomers, including a Northwestern University astrophysicist, has traced a series of mysterious radio pulses to an unprecedented home.
Starting a decade ago, astronomers have detected a pulse of radio emission every two hours, coming from the direction of the Big Dipper. After combining observations from multiple telescopes, the team can now reveal the culprit: a binary system with a dead star.
According to the new study, published in the journal Nature Astronomy, a red dwarf and white dwarf are orbiting each other so tightly that their magnetic fields interact. Each time they bump together — which is every two hours — the interaction emits a long radio blast.
Although astronomers previously only traced long radio pulses to neutron stars, the new discovery shows the movement of stars within a binary system also can emit long-period radio bursts.
“There are several highly magnetized neutron stars, or magnetars, that are known to exhibit radio pulses with a period of a few seconds,” said Northwestern astrophysicist and study coauthor Charles Kilpatrick. “Some astrophysicists also have argued that sources might emit pulses at regular time intervals because they are spinning, so we only see the radio emission when source is rotated toward us. Now, we know at least some long-period radio transients come from binaries. We hope this motivates radio astronomers to localize new classes of sources that might arise from neutron star or magnetar binaries.”
Kilpatrick is a research assistant professor at Northwestern’s Center for Interdisciplinary Exploration and Research in Astrophysics. Iris de Ruiter, a postdoctoral scholar at the University of Sydney in Australia, led the study. At the time of the research, she was a Ph.D. student at the University of Amsterdam in the Netherlands.
Continue to the full Northwestern news article.