A Repeating Radio Signal Is Coming From Another Planet, Scientists Say

Repeating radio signal comes from another planet that may harbor life, study finds

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Scientists have spotted a repeating radio signal from a nearby star system that hints at the presence of a magnetic field around one of its Earth-sized planets, a new study reports.

The discovery of a magnetic field – a key part of Earth’s ability to support life – could boost the search for extraterrestrial life and habitable planets in the universe if confirmed, but more research will be needed to present a clear case that the signals really are generated by a planet’s magnetic field.

Earth’s magnetic field has played a vital role in the survival of life by shielding the surface from harmful radiation from the sun and helping to maintain a stable atmosphere that nurtures our biosphere. For this reason, scientists believe that extraterrestrial life, if it exists, could also depend on the presence of robust magnetic fields around exoplanets, which are worlds orbiting other stars.

Scientists have previously observed the magnetic fields of giant Jupiter-scale exoplanets interacting with their host stars, in a process called star-planet magnetic interactions (SPI). However, Earth-sized exoplanets emit much weaker magnetic signals than gas giants, making it difficult to detect magnetism around rocky worlds.

Sebastian Pineda, a researcher at the University of Colorado at Boulder, and Jacqueline Villadsen, an assistant professor at Bucknell University, have spent years looking for these elusive signs of magnetic fields around small planets. Now the pair of astronomers present unprecedented evidence of repeated radio bursts that could be linked to a magnetic field around the Earth-sized exoplanet YZ Ceti b, located just 12 light-years from our solar system. .

YZ Ceti b completes an orbit in just two days, meaning it’s far too close to its star to support life, but this ultra-short year ‘also makes it a particularly promising case study for magnetic SPIs’ , according a study published on Monday In natural astronomy.

“It was super exciting to see the radio datasets showing that kind of signature,” Pineda said in an email to Motherboard. “We saw the initial burst detection and immediately coordinated observations for additional monitoring, based on the published planetary period, as we were looking for something happening at the same time in the planet’s orbit.”

“Once we had the additional data, Jackie would look at it and say to me, ‘hey, there are similar radio signals here, just when we were looking at it and hoping to see it,'” he continued. . “It was a bit of feverish excitement: ‘wow, we can really have it here!!’ I’m pretty sure I started pacing, imagining our next steps: okay, we have some work to do to really demonstrate this result, with all the implications, etc.

In their search for these signals, Pineda and Villadsen focused their attention on small, short-period planets because they might have a more visible magnetic signature due to their proximity to their stars. As these worlds pass through their orbits, any magnetic field they might possess could interact with the star’s magnetic field, creating a pattern of radio bursts from the star that can potentially be seen here on Earth.

The researchers believe they may have seen these repeated bursts from the YZ Ceti system, but they warn that this is not a slam-dunk case. It’s possible the signals are part of stellar radio activity from stars like YZ Ceti, which is a slowly rotating red dwarf, which would mean its emission has nothing to do with the planets in the system.

“There are still too many unknowns about the system, but I would say that we demonstrate the potential of radio data and star-planet magnetic interactions to lead to measurements of the magnetic field strength of planet-sized exoplanets. Earth – I don’t think we’re really here yet,” Pineda said.

“So we want to continue to monitor the star with radio observatories and look for additional recurrence of radio signals that occur periodically with the same position of the planet in its orbit,” he added. “This may be time consuming and a bit tricky to set up, but it will confirm that the radio detections are indeed planet-dependent, and not something the star does on its own.”

If this turns out to be the first detection of magnetic SPI around an Earth-sized exoplanet, it could help scientists search for habitable worlds in other stars. The caveat is that searching for magnetic signatures around rocky worlds in the habitable zones of their stars, where liquid water and life are thought to be more likely to exist, would be tricky because these planets have much larger orbits. large. This distance from the stars can be an advantage for any hidden aliens, but it also makes the magnetic interactions between stars and planets much weaker, to the point that some may not be detectable at all.

However, the new study offers a potential example of the kinds of signals you might expect to see from a system containing a magnetically shielded planet similar in size to Earth. With time and practice, scientists might be able to zero in on interesting targets, Pineda said, as part of a larger approach to assessing the chances that life could exist on other worlds.

“First, full confirmation of magnetic field intensities on exoplanets is a prerequisite for any broader understanding of habitability,” he explained. “It’s not just about temperature, but the whole star-planet system has to be thought of holistically, with magnetism as an important ingredient.”

“So if we know that these exoplanets have magnetic fields from the work of SPI, we can start thinking about questions like what properties do these planets have, and so how do planets in the habitable zone compare to each other? , and what are the chances that they too have similar magnetic fields, even if we cannot yet measure them for the [habitable zone] planets in particular,” concluded Pineda. “If you can deduce that a planet probably has its own field, that’s when you can start to wonder if individual planets are really hospitable.”

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