Observing magnetic star-planet interactions offers promise for determining the magnetic fields of exoplanets. Models of star-planet interactions predict that rocky exoplanets in close-in orbits around red dwarf stars can induce detectable stellar radio emission, manifesting as bursts of strongly polarized coherent radiation observable at specific planet orbital positions. Using the Karl G. Jansky Very Large Array, astronomers detected coherent radio bursts from the slowly-rotating red dwarf YZ Ceti, which hosts a compact system of terrestrial planets, the innermost of which — called YZ Ceti b — orbits with a two-day period.
YZ Ceti is a red dwarf located just 12 light-years away in the constellation of Cetus.
Also known as Gliese 54.1, IRAS F01100-1716, LTT 670 or TIC 439403362, the star is about 13% the mass of the Sun and 17% of its radius.
YZ Ceti and one of its three known planets, YZ Ceti b, provide an ideal pair because the planet is so close to the star that it completes a full orbit in only two days.
As plasma from YZ Ceti careens off the planet’s magnetic ‘plow,’ it then interacts with the magnetic field of the star itself, which generates radio waves strong enough to be observed on Earth.
The strength of those radio waves can then be measured, allowing astronomers to determine how strong the magnetic field of the planet might be.
“We saw the initial burst and it looked beautiful,” said Dr. Sebastian Pineda, an astronomer in the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder.
“When we saw it again, it was very indicative that, OK, maybe we really have something here.”
Dr. Pineda and his colleague, Dr. Jackie Villadsen from Bucknell University and Vassar College, theorize that the stellar radio waves they detected are generated by the interactions between the magnetic field of the exoplanet and the star it orbits.
However, for such radio waves to be detectable over long distances, they must be…
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