SETI: A Supernova to Synchronize Potential Communications with Extraterrestrials

Published by Adrien - Monday, February 19, 2024 - Other Languages: FR, DE, ES, PT
Source: The Astronomical Journal

Approximately 167,600 years ago, a blue supergiant star in the Large Magellanic Cloud exploded, creating the supernova SN 1987A. This cosmic event, which became visible on Earth on February 24, 1987, continues to arouse the curiosity of scientists. In particular, those at the SETI Institute suggest that advanced extraterrestrial civilizations could use this event as a landmark to synchronize their signals with us.

Image by the Hubble Space Telescope of the supernova remnant SN 1987A.
NASA Image

The SETI ellipsoid is defined as an elliptical volume with Earth and SN 1987A as focal points. Locations on its perimeter mark the points where light from the supernova had enough time to reach a star and for technological life on a planet orbiting that star to send a signal reaching us today. This approach is based on the Schelling point concept in game theory, used to coordinate actions between two parties without prior communication.

Historically, the idea of using astronomical events like supernovas for SETI research is not new. It was proposed as early as the 1970s, but it's the discovery of SN 1987A that truly opened this path. However, uncertainties related to the distance of stars near the ellipsoid have long represented a major obstacle, making it difficult to search for precisely synchronized signals.

An animation showing the growth of the SETI ellipsoid over time. The SETI ellipsoid is an ellipse in space with Earth at one of its foci and SN 1987A at the other. Stars on the perimeter of the ellipsoid would have seen the supernova, and any extraterrestrial signal could be synchronized with it.
Credit: Zayna Sheikh

The advent of the European Space Agency's Gaia mission, which aims to measure the positions and characteristics of one billion stars, has revolutionized this situation. Thanks to Gaia, astronomers have begun to obtain the precise measurements needed to explore the SETI ellipsoid around SN 1987A. A team led by James Davenport from the University of Washington in Seattle combined these data with observations from NASA's TESS satellite, identifying 32 stars in the Continuous Viewing Zone likely to be on the SETI ellipsoid.

Despite an in-depth analysis of the light from these stars, no anomalies indicating a technological signature were detected. However, the SETI ellipsoid continues to grow and move toward other stars, offering new opportunities for research. Future projects such as PANOSETI and the Vera C. Rubin Observatory promise to further expand the horizons of this fascinating quest for signals from civilizations beyond our own.
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