{"id":29984,"date":"2023-07-05T19:30:57","date_gmt":"2023-07-05T17:30:57","guid":{"rendered":"https:\/\/www.sciencefocus.com\/?p=147731"},"modified":"2023-07-05T19:38:27","modified_gmt":"2023-07-05T17:38:27","slug":"leading-astronomers-are-hunting-for-alien-messages-in-supernova-explosions-heres-why","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/rss_feed\/leading-astronomers-are-hunting-for-alien-messages-in-supernova-explosions-heres-why\/","title":{"rendered":"Leading astronomers are hunting for alien messages in supernova explosions. Here\u2019s why"},"content":{"rendered":"

Astronomers in the US think extra-terrestrials could take advantage of the spectacular cosmic events to inform us of their existence. <\/p>

By Colin Stuart\n \t\t<\/p>

Published: Wednesday, 05 July 2023 at 12:00 am<\/p>

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Imagine you\u2019re an alien on a distant planet. You\u2019re desperate to let everyone know you\u2019re there. Instead of howling aimlessly into the void, how can you give yourself the best chance of being heard? According to new research, extra-terrestrial civilisations could piggyback onto one of the brightest beacons in the known Universe<\/a>: a supernova.<\/p>\n

These cataclysmic explosions detonate as the biggest stars die. For a time, they shine as brightly as 10 billion Suns and release as much energy as the Sun<\/a> will emit in its entire 10-billion-year lifetime. When a supernova goes off, astronomers sit up and take notice.<\/p>\n

In May this year, astronomers exploded in a flurry of excitement when they spotted the supernova SN 2023ixf detonate in the nearby Pinwheel Galaxy (also known as M101).<\/p>\n

\u201cIt was the closest supernova in a decade,\u201d says James Davenport<\/a>, an assistant professor of astronomy from the University of Washington.<\/p>\n

\u201cIt was bright enough to see with amateur telescopes, even though M101 is 21 million light years away.\u201d<\/p>\n

A team led by Davenport has since examined the possibility that an alien civilisation may choose to flag us down by co-ordinating a message alongside the light<\/a> from this supernova in a ploy known as \u2018signal synchronisation\u2019. \u201cThey\u2019ll shout, \u2018We are here!\u2019 in a conspicuous way,\u201d Davenport explains.<\/p>\n

The idea is that that civilisation would know astronomers from other inhabited worlds like ours will probably be looking in the direction of the supernova, making the chances of that message being spotted far higher.<\/p>\n

So where exactly do we look? The sweet spot to search is defined by a rugby ball-shaped region within our Milky Way galaxy called the \u2018SETI ellipsoid\u2019 (SETI stands for the Search for Extra-Terrestrial Intelligence).<\/p>\n

But there is one caveat. The aliens in question have to be nearer to the supernova than us in order for them to be able to see its light first and then have time to quickly send on an accompanying message that will arrive on Earth close to when we see the supernova.<\/p>\n

\u201cIt\u2019s the same maths that goes into figuring out echoes,\u201d Davenport says. \u201cIt\u2019s civilisations on the perimeter of the ellipsoid that we\u2019re most interested in. We\u2019d have already missed the signals from those stars far inside it and stars outside may have seen the supernova, but any synchronised message wouldn\u2019t have had time to reach the Earth yet.\u201d<\/p>\n

Narrowing down the search<\/h2>\n

Working out which stars are in the right place has only recently become possible, thanks to modern space technology.<\/p>\n

\u201cMissions like Gaia have given us really precise locations of stars,\u201d Davenport says. \u201cThere are around 100 stars currently in the sweet spot.\u201d<\/p>\n

Armed with that knowledge, Davenport pointed the Allen Telescope Array in California at each of them over the course of a single weekend.<\/p>\n

Did he hear anything? Not yet. But all is not lost.<\/p>\n

\u201cWe are going to revisit them a few times over the next couple of months because there is some uncertainty over when the signals would arrive,\u201d Davenport says.<\/p>\n

That uncertainty stems from how quickly after the supernovae the alien civilisation would send on their message.<\/p>\n

\u201cWould they have to go to alien congress and ask permission to send it?\u201d Davenport asks.<\/p>\n

So, there could be a few weeks\u2019 delay. Revisiting the target stars also opens the door to being able to detect faint signals that slowly change, rather than taking just one snatched five-minute glimpse and saying nothing is there.<\/p>\n

\u201cThey could be sending a wave of information,\u201d Davenport says.<\/p>\n

The SETI ellipsoid is also constantly shifting to incorporate new stars as the passage of time allows both the light from the supernova and the relayed signals to travel further.<\/p>\n

So, we could be scanning stars on the perimeter of the ellipsoid for years to come. Plus, SN 2023ixf is just one supernova. Every nearby supernova has its own ellipsoid to comb through.<\/p>\n

In fact, Davenport\u2019s work predates this most recent explosion \u2013 he originally focussed on the supernova SN 1987A, which exploded in 1987.<\/p>\n

\u201cEven though it happened nearly 40 years ago there are still stars where the signal would only just be reaching us,\u201d he says.<\/p>\n

So, how does Davenport rate the chances of success?<\/p>\n

\u201cThey are low on any given day,\u201d he says. \u201cMy guess is that it could take us a thousand years, but that\u2019s okay.\u201d<\/p>\n

A millennium may sound like a long time, but humans have routinely carried out projects on such timescales. The University of Bologna, the world\u2019s oldest, has been teaching students ceaselessly since 1088, for example.<\/p>\n

\u201cYou have to start somewhere,\u201d Davenport says. \u201cIt\u2019s about leaving a legacy of data and of methodology.\u201d<\/p>\n

The best things take time and good things come to those who wait. One day measurements of a star on the edge of a supernova SETI ellipsoid might just go down in history as one of the most important observations ever made.<\/p>\n

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About our Expert, James Davenport<\/strong><\/h4>\n

James is a research assistant professor at the University of Washington\u2019s Department of Astronomy. His research is focused on large survey astronomy and has been published in the journals Research Notes of the American Astronomical Society<\/em>, The Astrophysical Journal<\/em> and The Astronomical Journal<\/em>.<\/p>\n

Read more about aliens:<\/strong><\/p>\n