Did astronomers detect a radio signal from an alien world about 51 light-years away? Here’s what we know
Scientists searching for signs of life beyond Earth have spotted something mysterious. They may have detected radio emissions from a planet orbiting a star beyond our solar system for the first time. The radio bursts appear to be emanating from the constellation Boötes.
“We present one of the first hints of detecting an exoplanet in the radio realm. The signal is from the Tau Boötes system, which contains a binary star and an exoplanet. We make the case for an emission by the planet itself. From the strength and polarization of the radio signal and the planet’s magnetic field, it is compatible with theoretical predictions,” explains Cornell postdoctoral researcher Jake D Turner, who leads the team of researchers. Their findings have been published in Astronomy & Astrophysics.
More than 4,000 exoplanets (any planet beyond our solar system) have been discovered by scientists and are considered ‘confirmed’ says NASA. Despite that, they have not found a radio emission emanating from any of them.
The detection of radio emissions from exoplanets can open up a ‘vibrant’ new research field. Observing an exoplanet’s magnetic field can provide astronomers valuable insights into the planet’s interior structure, atmospheric properties, and habitability, as well as the physics of star-planet interactions. Earth’s magnetic field protects it from solar wind dangers, keeping the planet habitable. “The magnetic field of Earth-like exoplanets may contribute to their possible habitability by shielding their own atmospheres from solar wind and cosmic rays, and protecting the planet from atmospheric loss,” explains Turner.
According to co-author Ray Jayawardhana, the Harold Tanner Dean of the College of Arts and Sciences, and a professor of astronomy, if confirmed through follow-up observations, “this radio detection opens up a new window on exoplanets, giving us a novel way to examine alien worlds that are tens of light-years away.”
What led to this discovery?
Two years ago, after examining the radio emissions from Jupiter, the authors scaled those emissions to mimic the possible signatures from a distant Jupiter-like exoplanet. Those results became the template for searching radio emission from exoplanets 40 to 100 light-years away. After poring over nearly 100-hours of radio observations, the researchers were able to find the expected hot Jupiter signature in Tau Boötes. “We learned from our own Jupiter what this kind of detection looks like. We went searching for it and we found it,” notes Turner.
The Tau Boötes system is approximately 51 light-years from Earth. The investigators made the discovery using the Low-Frequency Array (LOFAR), a radio telescope in the Netherlands. They uncovered emission bursts from the star-system that hosts a “so-called hot Jupiter, a gaseous giant planet that is very close to its own sun.” They also observed other potential exoplanetary radio-emission candidates in the 55 Cancri (in the constellation Cancer) and Upsilon Andromedae systems. Only the Tau Boötes exoplanet system exhibited a significant radio signature, “a unique potential window on the planet’s magnetic field,” the analysis reveals.
The signature, however, is weak and more observations will be needed to confirm this possible first detection of an exoplanetary radio signal. “There remains some uncertainty that the detected radio signal is from the planet. The need for follow-up observations is critical,” emphasizes Turner.
Radio waves from nearby star were picked up last year
In ongoing research, scientists are probing a signal that appears to be coming from the direction of the closest star to the Sun called Proxima Centauri, which is 4.2 light-years away from the Earth. Astronomers from the Breakthrough Listen project picked up a narrow beam of radio waves that they believe came from the Proxima Centauri star, reports The Guardian.
Breakthrough Listen is a massive scientific research program aimed at finding evidence of civilizations beyond Earth. “The scope and power of the search are on an unprecedented scale. The program includes a survey of the 1,000,000 closest stars to Earth. It scans the center of our galaxy and the entire galactic plane. Beyond the Milky Way, it listens for messages from the 100 closest galaxies to ours. The instruments used are among the world’s most powerful. They are 50 times more sensitive than existing telescopes dedicated to the search for intelligence,” describes the program website. It adds, “The radio surveys cover 10 times more of the sky than previous programs. They also cover at least 5 times more of the radio spectrum – and do it 100 times faster. They are sensitive enough to hear a common aircraft radar transmitting to us from any of the 1000 nearest stars.”
Breakthrough List used Australia’s Parkes Observatory to study Proxima Centauri when the team detected the signal, which they dubbed BLC-1. The radio waves were picked up in observations made between April and May 2019. “Analysis of the beam has been underway for some time and scientists have yet to identify a terrestrial culprit such as ground-based equipment or a passing satellite,” says the article.
Pete Worden, the former director of Nasa’s Ames Research Center in California and executive director of the Breakthrough Initiatives, told The Guardian that further analysis is needed before one can reach any definitive conclusion. “The Breakthrough Listen team has detected several unusual signals and is carefully investigating. These signals are likely interference that we cannot yet fully explain. Further analysis is currently being undertaken,” he says.