Why has the Search for Extraterrestrial Life (SETI) movement switch to sending signals instead of looking for them? A good answer would be that so many of the strange signals received, like the fast radio bursts (FRBs), are usually proven to have a natural cause – fast radio bursts are thought to be the result of colliding neutron stars or powerfully magnetic neutron stars known as magnetars. However, one signal has defied natural explanations – the famous WOW! signal named for the red exclamation written by a stunned astronomer on the computer printout which revealed it. Now, another astronomer using a new technique believes he’s traced the WOW! signal back to its star -- and it appears to have a habitable “Goldilocks” zone where an Earth-like planet could be populated with Earth-like beings sending a signal to what they think is a planet like theirs. Wow!
“Despite the WOW! Signal never repeated, the key aspect was its duration. The signal lasted for 72 seconds, but since this was the maximum amount of time that the Big Ear radio telescope was able to observe, it is likely that the signal would have lasted longer.”
In his new paper published in the International Journal of Astrobiology, science communicator Alberto Caballero explains the unique aspects of the WOW! signal which was recorded on August 15, 1977 by The Ohio State University's Big Ear radio telescope while scanning part of the constellation Sagittarius. The signal was 20 times stronger than those around it, causing astronomer Jerry Ehman to write "Wow!" in red on a computer printout of the Big Ear data. Caballero coordinates the Habitable Exoplanet Hunting Project, an international network of both professional and amateur astronomers who search for new potentially habitable exoplanets around non-flare G, K or M-type stars located within 100 light years of Earth. In that position, he has access to the European Space Agency's Gaia data – the Gaia space observatory is constructing a 3D catalog of more than 1 billion stars. That gave him an idea.
“In this paper it is analysed which of the thousands of stars in the WOW! Signal region could have the highest chance of being the real source of the signal, providing that it came from a star system similar to ours.”
In a “Why didn’t someone think of this before?” moment, Caballero matched the area of the Sagittarius constellation to the EAS Gaia data and began searching for G and K-type stars - our Sun is a G star, while K stars are slightly cooler – which could develop intelligent communicating life on Earth-like exoplanets in their habitable zones. A total of 66 G and K-type stars were evaluated. And?
“With the available data, the only potential Sun-like star in all the WOW! Signal region appears to be 2MASS 19281982-2640123.”
Is this a ‘drop the mic’ WOW! moment? It could be, but we won’t know for a while. 2MASS 19281982-2640123 is 1800 light years from Earth, so any “We got your message” signals sent to it won’t be responded to right away. However, it gives SETI listeners a pinpoint target to monitor for another WOW! signal with technology 50 years more advanced than the original Big Ear set-up – this is not meant to disparage Big Ear, since it’s still the only place where a strong signal from another star has been recorded.
Caballero hedges his bets by pointing out that 2MASS 19281982-2640123 is the best candidate, but five other stars were close but lacked enough data to make the cut. In fact, with more data, any of the 66 G and K-type stars he found could potentially be the WOW! source. Based on that, he suggests other astronomers scan for technosignatures from all of them.
While not quite a WOW-worthy moment, Alberto Caballero has moved the mic from the stand to his hand and in the proper position for dropping. All he needs in his other hand is a red pen to write “WOW!”.