Breakthrough Listen Search for Intelligent Life: First Results

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Breakthrough Listen — the largest ever research program aimed at finding evidence of intelligent life beyond Earth — has released its eleven events ranked highest for significance as well as summary data analysis results.

The Robert C. Byrd Green Bank Telescope in Green Bank, West Virginia, the United States. Image credit: Jiuguang Wang / CC BY-SA 2.0.

The Robert C. Byrd Green Bank Telescope in Green Bank, West Virginia, the United States. Image credit: Jiuguang Wang / CC BY-SA 2.0.

The Breakthrough Listen project, announced in 2015, is currently using the Green Bank Telescope in West Virginia, the Automated Planet Finder optical telescope at Lick Observatory and the Parkes Telescope in Australia, with plans to incorporate other large telescopes around the world.

The Breakthrough Listen science team has so far acquired several petabytes of data — available at breakthroughinitiatives.org — using these telescopes.

The researchers designed and built an analysis pipeline that scans through billions of radio channels in a search for unique signals from extraterrestrial civilizations.

“The basics of searching for signatures of extraterrestrial technology are quite simple,” the scientists explained.

“Artificial signals can be distinguished from natural processes through features like narrow bandwidth; irregular spectral behavior, pulsing, or modulation patterns; as well as broad-band signals with unusual characteristics.”

“However, human technology emits signals similar to the ones being searched for. This means that algorithms must be designed to ensure that signals are coming from a fixed point relative to the stars or other targets being observed, and not from local interferers.”

The initial results from deploying the pipeline on the first year of Breakthrough Listen data taken with the 100-m Green Bank Telescope have been submitted for publication in the Astrophysical Journal.

“With the submission of this paper, the first scientific results from Breakthrough Listen are now available for the world to review,” said Dr. Andrew Siemion, an astrophysicist and Director of the Berkeley SETI Research Center.

“Although the search has not yet detected a convincing signal from extraterrestrial intelligence, these are early days.”

Dr. Siemion and co-authors examined data on 692 stars, consisting of three 5-min observations per star, interspersed with 5-min observations of a set of secondary targets.

The total number of Breakthrough Listen target stars, described by Isaacson et al in a recent paper in the Publications of the Astronomical Society of the Pacific (arXiv.org preprint), is 1709.

“The stellar sample is defined by two selection criteria. The first (60 stars) is a volume-limited sample of stars within 16 light-years of the Sun,” the researchers explained.

“The second is a spectral class complete sample consisting of stars across the main sequence and some giant branch stars, all within 163 light-years.”

So far the team has picked up unusual signals from 11 Breakthrough Listen target stars:

(i) HIP 17147, also known as HD 22879, an F-type star approximately 83 light-years away;

(ii) HIP 4436, also known as Mu Andromedae and HD 5448, an A-type main sequence star approximately 130 light-years away from the Earth. It has double the mass of the Sun, 2.4 times the Sun’s radius, and is estimated to be about 600 million years old;

(iii) HIP 66704, also known as HD 119124, an F-type star;

(iv) HIP 99427, a variable star;

(v) HIP 39826, also known as BD+21 1764, a binary or multiple star system;

(vi) HIP 20901, also known as 79 Tau, b Tau and HD 28355, an A-type star 160 approximately light-years away from the Earth. This star is a member of the Hyades star cluster;

(vii) HIP 82860, also known as 19 Dra, h Dra and HD 153597, a binary star in the constellation Draco;

(viii) HIP 74981, also known as BD+29 2654, a K-type star;

(ix) HIP 65352, also known as HD 116442, a G-type star;

(x) HIP 45493, also known as 18 UMa, e UMa and HD 79439, a variable star of Delta Scuti type approximately 160 light-years away from the Earth;

(xi) HIP 7981, also known as 107 Psc and HD 10476, a K-type main sequence star approximately 24 light-years away from the Earth. The star is about 6 billion years old. It has 83% of the mass and 80% of the radius of the Sun.

“Eleven events rose above the pipeline threshold for significance, but further detailed analysis indicates that it is unlikely that any of these signals originate from artificial extraterrestrial sources,” the scientists explained.

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Emillio Enriquez et al. 2017. The Breakthrough Listen Search for Advanced Life: 1.1 – 1.9 GHz Observations of 692 Nearby Stars. ApJ, in press;

Howard Isaacson et al. 2017. The Breakthrough Listen Search for Intelligent Life: Target Selection of Nearby Stars and Galaxies. PASP 129: 054501; doi: 10.1088/1538-3873/aa5800

This article is based on text provided by Breakthrough Initiatives.

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