Astronomers may have discovered the firstradio signal from an exoplanet. In our never-ending quest to understand the universe and our place in it, precious little bursts of data can hint at whole new worlds. Dips in the star's light levels could betray the presence of rotating planets - and now astronomers have taken the first steps towards using the peaks of radio emission to uncover new exoplanetary secrets. "Observing planetary auroral radio emission is the most promising method for detecting exoplanetary magnetic fields," Cornell astronomer Jake Turner and his colleagues explained in a new paper, "knowledge of which will provide valuable information about the planet's internal structure, atmospheric escape and habitability." When the stellar wind - charged particles emanating from the host star - strikes the planet's magnetic field, its speed change can be detected as striking variations in radio emission, statistically described as "explosive."
Earth's own magnetic field warble and squeak,like alien birds, directs the solar winds. We have also heard similar screams from other planets in our solar system. Of course, to detect the whispers of such radio signals coming from an exoplanet, we first need a way to look beyond all the noise from Earth and elsewhere.
Several years ago, the team developed a programthe Northern Lights pipeline to do just that. They tested it on Jupiter, and then calculated what the radio emission from Jupiter would look like if it were much further away.
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There have already been some preliminary discoveriesnew planets using these radio emissions, including earlier this year, when astronomers linked radio wave activity to interactions between the magnetic field of the star GJ 1151 and a potential planet the size of Earth. But all of them have not yet been confirmed by subsequent radio observations.
So Turner's team decided to checka technique they developed, using the Netherlands Low Frequency Array Radio Telescope (LOFAR) to view three systems with known exoplanets: 55 Cancri, Upsilon Andromedae and Tau Boötis. Only the Tau-Boetis system, located 51 light years away, showed pips in radio data that matched the predictions of researchers from their tests with Jupiter. It came in the form of bursts of radiation of 14-21 MHz and is approximately within three standard deviations of confidence (3.2 Sigma).
In 1996, the exoplanet of hot Jupiter wasdiscovered in a 3.3128-day orbit around an incandescent young F-type star and a smaller red dwarf that make up the Tau Boethis binary. We're arguing for emissions from the planet itself, ”Turner said. "Based on the strength and polarization of the radio signal and the planet's magnetic field, this is consistent with theoretical predictions."
If their measurements are correct, they assume thatthe strength of the planet's surface magnetic field ranges from 5 to 11 Gauss (For comparison, Jupiter ranges from 4 to 13 Gauss, and measurements of its magnetic field showed that the planet has a core of metallic hydrogen). The observed radiation strength of the magnetic field is also in line with previous forecasts.
The magnetic field of Earth-like exoplanets cancontribute to their eventual habitability, Turner explained, by protecting their own atmospheres from solar wind and cosmic rays and protecting the planet from atmospheric loss. The signal they found is weak and still needs to be verified by other low frequency telescopes before researchers can confirm the true origin of the detected radio emissions. “We cannot rule out stellar flares as a source of emissions,” the researchers warned, but emissions from the planet remain likely.
If other telescopes such as LOFAR-LBA andNenuFAR can confirm these findings, such radio emissions from exoplanets will open up an exciting new area of research, providing us with a potential way to look further into distant, alien worlds. This study was published in the journal Astronomy & Astrophysics.