Saturday , October 16 2021

Unexpected radio signals from distant stars suggest hidden planets



Planet near the star

Using the world’s most powerful radio antenna, scientists have discovered stars that unexpectedly explode radio waves, possibly indicating the existence of hidden planets.

Dr. Benjamin Pope of the University of Queensland and colleagues at the Dutch National Observatory ASTRON have been searching for planets using the world’s most powerful Low Frequency Array (LOFAR) radio telescope located in the Netherlands.

“We have discovered signs of 19 distant red dwarf stars, four of which are best explained by the existence of planets orbiting them,” Dr. Pope said.

“We have known for a long time that the planets in our own solar system emit powerful radio waves as their magnetic fields interact with the solar wind, but the radio signals from planets outside our solar system had yet to be picked up.

“This discovery is an important step for radio astronomy and may lead to the discovery of planets throughout the galaxy.”

Previously, astronomers were only able to detect the nearest stars in constant radio emissions and all the rest of the radio sky was interstellar or exotic gas, such as black holes.

Now, radio astronomers are able to see old, simple stars when they make their observations, and with this information, we can search for any planet around these stars.

The team focused on red dwarf stars, which are much smaller than the Sun and are known to have intense magnetic activity that causes stellar flares and radio emissions.

But there were also some old, magnetically inactive stars that challenged conventional understanding.

Dr. Joseph Callingham of Leiden University, ASTRON and lead author of the discovery, said the team is confident that these signals come from the magnetic connection of stars and invisible orbiting planets, similar to the interaction between Jupiter and his moon, Io.

“Our own Earth has auroras, commonly recognized here as northern and southern lights, which also emit powerful radio waves; this comes from the interaction of the planet’s magnetic field with the solar wind,” he said.

“But in the case of Jupiter’s auroras, they are much stronger as their volcanic moon Io explodes material into space, filling Jupiter’s environment with particles that drive unusually powerful auroras.

“Our model for this radio broadcast of our stars is an enlarged version of Jupiter and Io, with a planet wrapped in the magnetic field of a star, which feeds material at large currents that similarly feed bright auroras.

“It’s a show that has caught our attention for years.”

The research team wanted to confirm that the proposed planets exist.

“We can’t be 100% sure that the four stars we believe have planets are actually planet hosts, but we can say that a planet-star interaction is the best explanation of what we’re seeing,” Dr. Pope.

“Monitoring observations have ruled out planets more massive than Earth, but there’s nothing to say a smaller planet won’t.”

Discoveries with LOFAR are just the beginning, but the telescope only has the ability to monitor stars that are relatively close, up to 165 light-years away.

With the Square Kilometer Array radio telescope in Australia and South Africa finally under construction, hoping to light up by 2029, the team predicts they will be able to see hundreds of relevant stars at much greater distances.

This work demonstrates that radio astronomy is on the cusp of revolutionizing our understanding of planets outside our solar system.

References:

“The population of M dwarfs observed at low radio frequencies” by JR Callingham, HK Vedantham, TW Shimwell, BJS Pope, IE Davis, PN Best, MJ Hardcastle, HJA Röttgering, J. Sabater, C. Tasse, RJ van Weeren, WL Williams, P. Zarka, F. de Gasperin and A. Drabent, October 11, 2021, Nature Astronomy.
DOI: 10.1038 / s41550-021-01483-0

“He TESS View of LOFAR “radio stars by Benjamin JS Pope, Joseph R. Callingham, Adina D. Feinstein, Maximilian N. Günther, Harish K. Vedantham, Megan Ansdell, and Timothy W. Shimwell, October 11, 2021, The Astrophysical Journal Letters.
DOI: 10.3847 / 2041-8213 / ac230c




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