A highly-elongated metallic or rocky object — known as 1I/2017 U1 ‘Oumuamua — came from another star system, prompting speculation it could be an interstellar spacecraft. So an international team of astronomers went back through observations from the Murchison Widefield Array (MWA) — a low-frequency interferometric radio telescope in Western Australia — to check for radio transmissions coming from the object between the frequencies of 72 and 102 MHz. While the team did not find any signs of intelligent life, their work helped expand the search for extraterrestrial intelligence (SETI) from distant stars to objects closer to our home planet.
This artist’s impression shows the first interstellar asteroid — 1I/2017 U1 (‘Oumuamua). Image credit: M. Kornmesser / ESO.
‘Oumuamua was discovered by the Pan-STARRS 1 telescope in Hawai’i on October 19, 2017, passing Earth at about 85 times the distance to the Moon. It is the first object discovered in the Solar System that appears to originate from another star system.
Its high speed — 196,000 mph (315,000 kmh) at its peak — suggests it is not gravitationally bound to the Sun, but will continue its voyage back into interstellar space.
It has a highly unusual structure for an asteroid — an elongated cigar shape, about 1,312 feet (400 m) in length but with width and height perhaps only 1/10th as long.
“Based on the interesting but highly unlikely suggestion that ‘Oumuamua is an interstellar spacecraft, due to some unusual orbital and morphological characteristics, we examined MWA radio data for signals that might indicate the presence of intelligent life associated with ‘Oumuamua,” said Curtin University’s Professor Steven Tingay and colleagues.
The astronomers were able to look back through all of the MWA’s observations from November, December 2017 and early January 2018, when ‘Oumuamua was between 59 million and 367 million miles (95-590 million km) from Earth.
“We found nothing, but as the first object of its class to be discovered, ‘Oumuamua has given us an interesting opportunity to expand the search for extraterrestrial intelligence from traditional targets such as stars and galaxies to objects that are much closer to Earth,” Professor Tingay said.
“This also allows for searches for transmitters that are many orders of magnitude less powerful than those that would be detectable from a planet orbiting even the most nearby stars.”
The team’s results were published in the April 9, 2018 issue of the Astrophysical Journal (arXiv.org preprint).
_____
S.J. Tingay et al. 2018. A Serendipitous MWA Search for Narrowband Signals from ‘Oumuamua. ApJ 857, 11; doi: 10.3847/1538-4357/aab359
