by If aliens are synchronizing their signals with light coming from the 1987A supernova, then the search for extraterrestrial information (SETI) on the situation. Scientists at the institute say they may be able to find such signals by looking for them on something called the “SETI Ellipsoid.”
About 167,600 years ago, a blue super star exploded as a supernova in the Large Magellanic Cloudis small, satellite a galaxy in our own neighborhood The Milky Way. Light that came from that supernova ran through it space at 299,792,458 meters per second (186,282 miles per second).
Then, on 24 February 1987, he arrived World.
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The supernova was called SN 1987A, and its light did not stop on Earth. It continued, deeper and deeper into our galaxy where other alien life could be seen. This is where the concept of the SETI Ellipsoid comes from. It is defined as an elliptically shaped volume, with Earth at one focus and SN 1987A at the other; its outline indicates locations where the supernova’s light has had enough time to reach a star, and for any technological life on a planet orbiting that star to send out a signal that would reach us now.
The idea that we can use the SETI ellipsoid as a point is called Schelling, a concept related to game theory. It describes a kind of focal point around which two protagonists—in this case, aliens and human astrologers who are watching or listening to their signals—can coordinate their actions without first communicating their intentions. If that sounds complicated, consider that SETI is using Schelling points from Frank Drake’s Project Ozma, the first ever SETI search that took place in April and May 1960. Drake had searched for signals radio at the iconic hydrogen wavelength of 21 centimeters because of it. aliens would understand our astronomers regularly look at that wavelength. Transmission at such a commonly used wavelength, he said, would increase the signal’s detectability.
“As Dr. Jill Tarter often says, SETI searches are like looking for a needle in a 9-D haystack,” said Sofia Sheikh of the SETI Institute and the University of California, Berkeley in statement. “Any technique that helps us prioritize where to look, like the SETI Ellipsoid, could give us a shortcut to the most productive parts of the haystack.”
It is hoped that technological aliens who saw SN 1987A would synchronize their signals with it, knowing that we would be looking for it on the SETI Ellipsoid. The problem, however, is that, until recently, it was impossible to search for the ellipsoid with reasonable accuracy.
To understand why, let’s take a look at some SETI and astronomical history.
The concept of the SETI Ellipsoid is not new. It was first described independently by TB Tang in the Journal of the British Interplanetary Society in 1976, and by the Soviet astronomer PV Makovetskii in 1977. At the time, there were no clear goals for establishing the SETI Ellipsoid; Makovetskii suggested using Nova Cygni 1975, which was an eruption a white ox accumulate material from a companion red ox star, which prompted the system to brighten significantly for about a week.
After the discovery of SN 1987A, Hungarian astronomer Iván Almár realized that he had created a new object SETI Ellipsoid, and in 1994, Argentinian astronomer Guillermo Lemarchand described a search using that ellipsoid. But, uncertainties in the distance stars near the circumference of the superimposed ellipsoid. Uncertainties in distance correspond to uncertainties in i time; if we get the distance to a star wrong by even half a light year, for example, that means our search for signs of synchronization would be six months too early or too late. And it could be all the time with these technosignature hunters.
It was only in the last decade, with the arrival of the European Space Agency’s Gaia mission, which is intended to measure the positions and characteristics of a billion stars, that astronomers began to collect distances to the stars with the necessary precision to search for the SETI ellipsoid SN 1987A. So, a team led by James Davenport from the University of Washington in Seattle combined the Gaia data with stars on the SETI Ellipsoid in the Continuous Field of View of NASA’s Transiting Exoplanet Survey Satellite (TSES).
TESS spends a year looking at each celestial hemisphere, and divides those hemispheres into sectors. TESS observes each sector for 27 days, watching for exoplanetary transits, before moving on to the next sector. However, there is a region around each celestial pole that can be seen in each sector. This is the Continuous Viewing Zone – TESS collects data from it for a full year.
Davenport’s team identified 32 stars in the Continuous Visual Belt of the Seti Ellipsoid, and the year’s worth of data allowed some latitude for any long-term uncertainty in their lengths. As TESS is an optical telescope, it can only detect optical signals and not radio messages. Davenport’s team studied the light of 32 stars during that year, looking for any anomalies that indicate a technological signature. These anomalies could include brightening from a laser signal, an improper transit from an artificial structure, or even an artificial explosion that mimics the light curve of SN 1987A. In 1994, Lemarchand suggested looking for a “fake pulsar” signal, as aliens might know that astronomers would be looking for a signal. pulsar born in the fires of the supernova. (So far, no pulsars have been found in SN 1987A.)
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Suffice it to say, Davenport’s team found no anomalies and thus no evidence of aliens. However, the SETI Ellipsoid is still growing (at the speed of light, actually) and will move on to other stars in the future.
The to come PANOSETI (Panoramic SETI), which will continuously observe the entire visible sky from the Lick Observatory in California and search for optical and near-infrared laser signals, perfect for exploring the SETI Ellipsoid. The IS Vera C. Rubin Observatory in Chile could also be a game changer when it will be operating later in the decade.
“New surveys of the sky provide brand new opportunities to coordinate technosignatures with the search for supernovae,” said co-researcher Bárbara Cabrales of Smith College in the United States in the statement.
The analysis of the SETI Ellipsoid and the results from the stars in the TESS Continuous Observing Zone were described last year in The Astronomical Journal.
