11 hours ago
SKA Radio Array To Spot Habitable Exoearths Via Their Magnetic Auroras
Two people admiring the green light of Aurora Borealis standing on the wild Skagsanden beach, ... More Lofoten Islands, Norway
Radio astronomy has long been unsung and underappreciated, largely because it's never been able to cough up the kind of jaw-dropping visual images that are routine with large optical telescopes. But that could all change when the 1-billion-euro Square Kilometre Array Observatory comes online in Western Australia and South Africa in 2027.
The SKAO was primarily funded to unravel the mysteries of dark energy, the evolution of galaxies through cosmic time and to further constrain Einstein's theory of relativity. But at least one Netherlands-based radio astronomer is using that country's know-how in the low-frequency radio spectrum to look for emissions from far flung earthlike extrasolar planets.
We really need all the sensitivity SKA-Low can get us as this will be a very faint signal of around a 100 MHz, Joe Callingham, Head of the Square Kilometre Array (SKA) Science Group at ASTRON, The Netherlands Institute for Radio Astronomy, tells me in his office at the University of Amsterdam.
That's basically the same frequency as the FM dial on your car radio.
If you ever go hunting for auroras in Norway or Antarctica, you want the Sun to be pumping out radiation, preferably a coronal mass ejection that hits our atmosphere and causes those big, beautiful lights, Callingham tells me. But if you could turn your eyes into radio receivers, they'd also be incredibly bright in the low frequency spectrum, he says.
Like a shield, Earth's geomagnetic field protects us from solar activity, so we really think having a geomagnetic field is super important for habitability, says Callingham.
And without a geomagnetic field, even if astronomers find an earthlike planet in the habitable zone of a nearby red dwarf star, these M-type red dwarfs pump coronal mass ejections daily.
So, most likely, you've got a barren rock sitting in a Goldilocks habitable zone, says Callingham. Because without a magnetic field a planet will lose its atmosphere, and its oceans will be boiled away, he says. So, we really think the magnetic field is vital piece of this puzzle, and radio is the only real way to detect and measure that, says Callingham.
Remote Desert Location
From a remote site in Western Australia, SKA-Low's antennas are divided into 512 stations, with 256 antennas per station, notes SKAO. From a central compact core measuring 1km across, with a maximum distance of 74 km between the two furthest stations, they note.
How does it work?
SKA-Low is a "mathematical" telescope that works by filtering out what is not desired from the observable sky, says the SKAO. Its antennas see the whole sky, and through data processing astronomers can "point" in different directions even though the antennas have no moving parts, SKAO notes.
As for what the SKAO will bring to the data processing table?
The big thing that's changed is professionalization of the software; we've hired software engineers to really help us because it's very computationally expensive radio astronomy, says Callingham.
But Callingham and colleagues already have lots of experience in the low frequency regime since The Netherlands has built and has been operating their LOw Frequency ARray (LOFAR) since 2010.
A Great Legacy
Radio astronomy in The Netherlands has a very long tradition dating back to World War II and we've capitalized on that expertise, says Callingham. Without the algorithms we've developed here and the engineering skills we've built over time in The Netherlands, the SKA wouldn't be possible, he says.
A Planet Hunter
This radio method will also be a new way to discover exoplanets, says Callingham. M-type red dwarfs are the best spectral type to survey for these auroras since they host largest number of nearby planets (and have strong magnetic fields), he says.
The Bottom Line?
The SKA is going to revolutionize our understanding of the universe, largely because it's going to have a sensitivity and the resolution that's unparalleled by any other radio telescope that has ever been built, says Callingham. And I think it will find the first auroras on other planets outside of our solar system, he says.
