Astronomers Intrigued by ‘Probable’ Alien Signals in Stellar Spectra


A paper accepted for publication in PASP claims the detection of “signals probably from Extra-Terrestrial Intelligence.” A preprint titled “Discovery of peculiar periodic spectral modulations in a small fraction of solar type stars” is available on arXiv. The SETI community is skeptical but actively looking.

In 2012 Ermanno Borra, a researcher at Laval University in Quebec, suggested that the best strategy for alien civilizations to announce their existence would be to send laser pulses.

Assuming that the transmitter is based on the aliens’ home planet, the pulses would be lost in the light from the aliens’ star. But the short optical bursts could be detected, as spectral modulations in the star’s light, by analyzing spectral survey data acquired for astrophysics research. The aliens would think that all advanced civilizations engage in astronomical and astrophysical observations, and add their signals to data that are already collected. Of course, they would send a signal that is “so unusual that it can only be artificial.”

A most unusual signal would be made of a spectral modulation of the spectrum that is so unusual that it warrants more observations, which will then reveal that it is artificial.

Borra demonstrated that even today, with our relatively primitive technology, we could use a laser similar to the Helios laser at the Lawrence Livermore National Laboratory to send laser pulses that could be detected, at a distance of 1000 light years, by aliens with technology similar to ours.

An important consideration is that Borra’s strategy can save money to the receiving civilization. In fact, though the required data analysis methods are sophisticated, the detectors are relatively cheap and already used for routine astrophysics. So if the aliens keep the funding problems of SETI research in mind – they could guess that some things stay the same everywhere in the universe – this is the strategy they would use.

In the 2012 paper, Borra derived plausible features for alien signals sent with laser pulses to optimize detection, and proposed to search for SETI signals in the data collected by spectroscopic astronomical surveys like the Sloan Digital Sky Survey (SDSS).

In the new paper, Borra and graduate student Eric Trottier report that 2.5 million spectra in the SDSS data have been analyzed to detect periodic spectral modulations, which have been found in 234 stars similar to our Sun. The researchers consider possible astrophysical phenomena that could produce the unexpected features found in the data, but find them “highly unlikely.”

“Finally we consider the possibility, predicted in a previously published paper, that the signals are caused by light pulses generated by Extraterrestrial Intelligence to make us aware of their existence,” conclude Borra and Trottier.

We find that the detected signals have exactly the shape of an ETI signal predicted in the previous publication and are therefore in agreement with this hypothesis. The fact that they are only found in a very small fraction of stars within a narrow spectral range centered near the spectral type of the sun is also in agreement with the ETI hypothesis.

Of course, the authors acknowledge the (unlikely) possibility that the signals are due to highly peculiar chemical compositions in a small fraction of stars and note that, at this stage, the alien hypothesis needs to be confirmed with further work.

Breakthrough Listen Will Conduct Follow Up Observations

Automated Planet Finder
Automated Planet Finder

The SETI community is skeptical at this moment. However, the Breakthrough Listen project at UC Berkeley will conduct follow up observations of the reported anomalous spectral features with the 2.4-meter Automated Planet Finder optical telescope at Lick Observatory. “We look forward to consulting with Professor Borra and his team on these observations, as well as additional follow-up investigations using other data sources,” notes the UC Berkeley communication.

The global Breakthrough Listen initiative, launched in July 2015 with million funding from Russian billionaire entrepreneur Yuri Milner and the participation of celebrities and top scientists including Stephen Hawking, wants to conduct the most powerful, comprehensive and intensive scientific search ever undertaken for signs of intelligent life beyond Earth.

In related news, the National Astronomical Observatories of China (NAOC) is joining forces with Breakthrough Listen to launch a coordinated search for evidence of intelligent life beyond Earth, using the brand-new FAST telescope – the world’s largest filled-aperture radio receiver.

But today’s trending headline about aliens is probably their appearance in the Podesta emails disclosed by Wikileaks. Late NASA astronaut Edgar Mitchell emailed Podesta to discuss the disclosure of the US government UFO files, with tantalizing hints at alien presence and “Zero Point Energy.” The emails mention Quantrek, a research organization created by Mitchell.

Images from Shutterstock and Wikimedia Commons.

Giulio Prisco is a freelance writer specialized in science, technology, business and future studies.