The brightness of the object varies dramatically, and the signal switches on and off apparently at random, said Ziteng Wang, lead author of the new study in The Astrophysical Journal and a doctoral student in the School of Physics at The University of Sydney.
“The strangest property of this new signal is that it has a very high polarisation. This means its light oscillates in only one direction, but that direction rotates with time,” he said in a news release.
The team initially thought it could be a pulsar — a very dense type of rapidly spinning neutron (dead) star, or a type of star that emits huge solar flares. The signals from this new source of radio waves, however, don’t match what astronomers expect from these types of stars.
The fickle object has been named after its coordinates in the night sky: ASKAP J173608.2-321635.
“This object was unique in that it started out invisible, became bright, faded away and then reappeared. This behaviour was extraordinary,” said study coauthor Tara Murphy, a professor at the Sydney Institute for Astronomy and the School of Physics at The University of Sydney, in the release.
However, the Parkes telescope failed to detect the source.
“We then tried the more sensitive MeerKAT radio telescope in South Africa. Because the signal was intermittent, we observed it for 15 minutes every few weeks, hoping that we would see it again,” Murphy said in the statement.
“Luckily, the signal returned, but we found that the behaviour of the source was dramatically different — the source disappeared in a single day, even though it had lasted for weeks in our previous ASKAP observations.”