The Wow! signal, sun-like stars, and an abundance of hydrogen

28 November 2024

Did an extra-terrestrial intelligence attempt to message us in the distant past? Or did an Earth based radio telescope, nicknamed Big Ear, inadvertently eavesdrop in on a snippet of a conversation between two other alien civilisations? These are among some of the many explanations advanced to understand the so-called Wow! signal, a suspected narrowband radio transmission detected by Jerry R. Ehman, an astronomer working on an early inception of the SETI Project, almost fifty years ago.

Despite being a narrowband signal, which might indicate the presence of intelligent life somewhere, there could any number of explanations to account for the supposed transmission. Some sort of natural phenomena, one we do not yet understand, may well be the cause.

But that hasn’t stopped anyone from daring to live in hope, even though no identical, or repeat, signals have seemingly been observed since. Alberto Caballero, a Spanish astronomer, using data collected by the Gaia space observatory, analysed the area of the galaxy where the Wow! originated. He found about sixty stars, similar to our star, the Sun, in the region. For people searching for signs of extra-terrestrial intelligence, sun-like stars are a common starting point.

If intelligent life emerged here on Earth, a planet orbiting a G-Type main-sequence star, the Sun, then just maybe the same could happen on an Earth-like plant, around another star similar to the Sun, somewhere else. In his research, Caballero identified a candidate star of particular interest to him, with the catchy name of 2MASS 19281982-2640123, located some eighteen-hundred light years from us. Take a second to consider that. Travelling at the speed of light, the would-be transmission was sent during the height of the Roman Empire.

But, in a galaxy quite possibly devoid of intelligent life, with the exception of humanity — if current indications are anything to go by — how incredible would it be that a narrowband-radio-signal-transmitting-alien-civilisation turned out to be — on a cosmological scale — a mere hop, skip, and jump, away?

2MASS 19281982-2640123, and any planets the star may host however, was eliminated after a radio telescope scan last year. Observations, conducted by two radio telescopes, failed to detect any technosignatures, which would point to the presence of a technological civilisation. But not all is lost, there are another sixty or so possible stars Caballero, and other astronomers, could look at next.

Then again, for those hoping the Wow! was sent by someone, far, far away, perhaps all is lost. Fred Watson, an Australian astronomer, writing for Australian Geographic, says some new research conducted by American and Colombian scientists, has discovered numerous instances of Wow! signal like phenomena throughout space:

In research recently announced, a team from the USA and Colombia have used data from a since decommissioned radio telescope at Arecibo in Puerto Rico to look for similar phenomena to the Wow! signal. And they’ve found them, differing only from the original in their lower intensity. All these signals carry the wavelength signature of cold hydrogen, the most abundant element in the universe. It’s commonly expected to be the preferred wavelength for communication by intelligent extraterrestrials — hence the Big Ear’s tuning to this wavelength in the original SETI experiment.

This is not the first time hydrogen has been theorised to be somehow responsible for the Wow!. In 2017, a group of researchers at the Center of Planetary Science said they had determined a hydrogen cloud, accompanying a comet, that was in the region of the galaxy where the Wow! was detected, was the cause. Other scientists, however, were not comfortable with the idea.

It remains to be seen what other astronomers make of the conclusion of the American and Colombian scientists. It seems to me though, the remaining, unchecked sun-like stars, and any surrounding planets, Caballero suspects may be the origin of the Wow!, should be looked more closely anyway. Because one never knows what lurks behind all that hydrogen.