Astronomers discover four exoplanets while monitoring faraway red dwarf stars using radio astronomy.
International researchers, including Dr Benjamin Pope of The University of Queensland and colleagues at the Netherlands' national observatory ASTRON, have been observing activity from nearby red dwarf stars. The team of scientists, at ASTRON, UQ, and Leiden University in the Netherlands, started their search for the proposed exoplanets using the Low Frequency Array (LOFAR), the world’s most sensitive radio telescope. LOFAR operates at low radio frequencies - just above those of FM radio stations.
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The signals they received are the result of an interaction between the exoplanet's magnetic field and the magnetic field of the star, which generates intensely strong auroras. The researchers identified signals from 19 red dwarf stars, four of which generate signals indicating the presence of planets. Planets that orbit red dwarfs often have temperatures like those on Earth.
Dr Benjamin Pope led the group that compared the findings with optical telescope data from the same area of the sky. “We can’t be 100% sure that the four stars we think have planets are indeed planet hosts, but we can say that a planet-star interaction is the best explanation for what we’re seeing,” says Pope.
Radio signals from planets beyond our solar system have never previously been firmly detected. If this can be independently confirmed, it is a milestone for radio astronomy and opens a new window on multiwavelength exoplanet astronomy.
LOFAR is a prototype or “pathfinder” that is part of the development of the Square Kilometre Array, which will be the world’s largest telescope, split between Western Australia and South Africa. “LOFAR’s a mini version of what we can expect in WA in five to 10 years,” Pope said.
Joseph Callingham, lead researcher from Leiden University says “We are just seeing the tip of the iceberg with LOFAR. The Square Kilometre Array [SKA] is going to be nearly an order of magnitude more sensitive, so we will be able to find many, many more of these systems – those that are fainter and closer to Earth, and those far away.”
The team is now working on confirming the exoplanets independently using the radial velocity method, with the Hobby-Eberly Telescope in Texas, US, and the Calar Alto Observatory in Spain.
