A major discovery was made by astronomers this week- they have discovered stars emitting radio transmissions that hint at hidden planets orbiting them. A low-frequency array (LOFAR) in the Netherlands was used to pick up the signals, which are the strongest in the world.
Astronomers are still trying to figure out whether life exists in the system, but a new technique of detecting hidden planets could hint at a solution. Are we alone in the universe? Researchers at the Dutch national observatory ASTRON detected the signals along with Dr Benjamin Pope from the University of Queensland. Planets have been discovered with LOFAR by astronomers.
Four of the observations are best explained by their being orbited by planets, which were observed near 19 distant red dwarfs. Radio signals from planets outside of our solar system are yet to be detected, according to the astronomers. These astronomers also said in their statement that “We know planets in our solar system emit powerful radio waves as their magnetic fields interact with the solar wind”.
Red dwarf suns distant from earth may have aurorae produced by exoplanets.
Through an auroral method, exoplanets may be detected via the aurora their host stars produce. Researchers recently announced the existence of the star through ASTRON’s Low-Frequency Array radio telescope (LOFAR), located in Exloo, the Netherlands, and spread across several European sites.
Researchers examined stars within our solar system that are red dwarf stars. Solar-Earth interactions produce powerful aurorae, along with copious quantities of radio signals, as the space weather emanating from the Sun encounters the Earth’s magnetosphere. It was initially believed that Earth-Moon interactions would produce the same phenomena.
Exo-auroras have not yet been discovered, but a search has proven fruitless to date. Low-frequency radio waves can be induced by such interactions, and radio observatories aren’t suitable for detecting these waves. Similarly, we note the appearance of auroras on Jupiter, which are caused by the powerful Io flux tube connecting the innermost Galilean moon with the planet. Despite its strength, this radiation source can be picked up by amateur radio telescopes, and spacecraft such as NASA’s Juno mission must avoid passing near it or risk damaging their electronics.
Here’s the lowdown on LOFAR
It was the perfect survey method for LOFAR. LOFAR is a network of 20,000 low-frequency radio antennae distributed throughout 52 sites in nine countries across Europe. LOFAR act as one large antenna for astronomy because it is so large, with a diameter of 2 000 kilometres. As a space telescope completed in 2012, LOFAR has already imaged solar wind, discovered new pulsars, and probed the re-ionization era of the early Universe.
Joseph Callingham (Leiden University) says that we have known for a long time that the magnetic fields of planets in our solar system interact with the solar wind to emit powerful radio waves. LOFAR was the only instrument that could detect aurora emission beyond our Solar System. Lofar is one of the best examples of a simple, low-cost array that produces maximum scientific results.
By utilizing electronic beam steering, the array actually ‘slews’ towards targets across the sky, allowing the omnidirectional system to observe multiple targets simultaneously. Having determined 19 red dwarfs emitting key radio signatures, the team subsequently determined that these objects may be close to an unknown exoplanet. A red dwarf star interaction with an exoplanet is similar to the interaction between Io and Jupiter and thus emits a similar low-frequency radio signal. Their approaches and retreats from the LOFAR receiver, as the planet orbits the host star, are also recognizable.
Radio lights should blink and turn on and off like lighthouses, says Callingham in a recent press release. This periodicity should be reflected in the LOFAR data. A NASA satellite, NASA’s Transiting Exoplanet Survey Satellite (TESS), played a role in the study by making follow up observations that ruled out stellar activity around the target stars. A star identified in the study as possibly hosting an aurora-generating exoplanet is GJ 1151, located 26.2 light-years distant in the constellation Ursa Major, the Great Bear.
LOFAR’s future is bright, but it’s just getting started. With the array, we should be able to detect interactions between red dwarfs and their exoplanets at a distance of about 165 light-years, covering potentially thousands of system red dwarfs. Square Kilometre Array, which is due to come online in 2029, will be able to extend this capability even further, to a radius of hundreds of light-years.
And yet, more than two decades ago, there were no exoplanets known to exist, and many astronomers believed it was likely that there would remain no exoplanets. It’s 2021 now, and 4,848 worlds exist beyond our solar system, discovered by radial velocity, transits, pulsar timing, and more; a repertoire that includes low-frequency radio wave detections of extragalactic auroras.
It is currently possible to identify the nearest radio-emitting stars by using a radio telescope. There were no radio emissions in the radio sky until recently since all radio emissions were due to interstellar dust or black holes. As astronomers focus on red dwarf stars, plain old stars, with an intense magnetic activity responsible for stellar flares and radio emissions are now able to be observed when they conduct observations.
The team believes the signals are generated by magnetic connections between stars and unknown planets, in the same way, Jupiter and its moon Io interact with each other. Earth also has auroras, known as northern and southern lights in the UK, due to the interaction between its magnetic field and the solar wind, which also emits powerful radio waves. Dr Joseph Callingham of Leiden University is one of the scientists who made this discovery.”
There may be hidden planets in the system that could provide clues to whether life exists in the universe.
Are we alone in the universe?Â
The model was developed to study the interaction of the magnetic field and the solar wind, just as it occurs on Jupiter and its moon Io, which causes auroras on the largest planet in the solar system. These auroras are much stronger than those we see on Earth.
The researchers scaled up the model to detect radio emissions from distant stars and the research team modelled this radio emission from our stars as a scaled-up version of Jupiter and Io, with the planet encased in the magnetized field of a star, feeding material into vast currents that amplify the same types of bright aurorae. Although these interactions are lightyears away, they point to the presence of stars and planets within their system.
While we can’t be certain that the four stars we believe have planets host planets, we are confident that planet-stars interactions explain what we’re seeing,” Dr Pope said.
Further observations have eliminated planets with a mass greater than Earth, but there isn’t any conclusive evidence that a smaller planet would not do this as well and seeing that the discovery is a major step forward for radio astronomy and could potentially lead to the discovery of planets throughout the galaxy, researchers await the launch of the under-construction Square Kilometre Array by 2029 that will “help see hundreds of relevant stars at much greater distances.”
So now is the high time that we sit and wait what more we can discover from this universe. But we can assure something, that our universe is a mystery box itself.
