Astronomers say they have detected "strange signals" coming from the direction of a small, dim star located about 11 light-years from Earth.
Researchers picked up the mysterious signals on May 12 using
the Arecibo Observatory, a huge radio telescope built inside of a Puerto Rican
sinkhole.
The radio signals appear to be coming from Ross 128, a red
dwarf star that's not yet known to have any planets and is about 2,800 times
dimmer than the Sun.
Abel Méndez, an astrobiologist at the University of Puerto
Rico at Arecibo, said the star was observed for 10 minutes, during which time
the signal was picked up and "almost periodic".
Méndez said it's extremely unlikely that intelligent
extraterrestrial life is responsible, but noted the possibility can't yet be
ruled out.
"The SETI [Search for Extraterrestrial Intelligence]
groups are aware of the signals," Méndez wrote in an email to Business
Insider.
While Arecibo is known for its role in efforts to search for
signals from aliens, it's also great for looking at distant galaxies and
pinging near-Earth asteroids.
Méndez thinks the signal is more likely from something
humans put in space, perhaps a satellite that passed thousands of miles
overhead.
"The field of view of [Arecibo] is wide enough, so
there is the possibility that the signals were caused not by the star but
another object in the line of sight," Méndez said, adding that "some
communication satellites transmit in the frequencies we observed."
However, in a blog post about the mystery of Ross
128, he wrote that "we have never seen satellites emit bursts like
that" and called the signals "very peculiar".
Another possible explanation is a stellar flare, or outburst
of energy from the star's surface. Such bursts from the sun travel at
light-speed, emit powerful radio signals, and can disrupt satellites and
communications on Earth, as well as endanger astronauts.
Solar flares can also be chased by a slower-moving yet more
energetic coronal mass ejections: a flood of solar particles that can distort
our planet's magnetic field, generate geomagnetic storms, and cripple power
grids and fry electronics.
To see if the signals are still there, Méndez said Arecibo
is going to stare down Ross 128 and its surroundings many more times, starting
July 16.
"Success will be to find the signal again in the star
but not in its surrounding[s]. If we don't get the signal again then the
mystery deepens, " he said. "We are not sure if we can get to the
bottom of this mystery from just the next observations if that was a rare
event."
But FAST isn't operational right now, since it's being
calibrated, and Méndez said he doesn't know when it will be back online.
Seth Shostak, a senior astronomer at the SETI Institute,
confirmed that the group is "well aware of the signals" and might use
its powerful Allen Telescope Array in California "to check them out."
"The chances are high that they're terrestrial
interference, in fact. That's really always been the case," Shostak told
Business Insider in an email.
Right now there's really only one compelling signal from outer space that might come from aliens: "[T]he WOW signal," Shostak said. "That one is still quite odd."