Astronomers have detected ‘unusual signals’ emanating from the Milky Way’s core, leading them to suspect that the peculiar radio waves are originating from an undiscovered stellar object.
According to NASA, objects throughout the galaxy have shifting magnetic fields that create radio waves. A star emits light over the electromagnetic spectrum during its life cycle, including certain wavelengths that are invisible to the naked eye. The amount of light emitted by a star is determined by where it is in its life cycle.
However, the radio waves detected by a group of international experts are remarkable for a number of reasons. The object’s brightness varies greatly, and it switches on and off at random, Ziteng Wang, lead author of the research reported.
‘The strangest feature of this new signal is its extremely high polarisation. This means that its light only oscillates in one direction, but that direction rotates over time. It’s unlike anything we’ve ever seen,’ Wang said in a statement.
Wang explained that his team initially thought that the signal came from a pulsar, which is a dense, rapidly spinning star that has imploded and emits solar flares as a result. Solar flares can last from minutes to hours, making them appear random. However, this was ruled out as a possible explanation because the radio waves ‘do not fit what they expected from those types of astronomical objects.’
The finding was made in west Australia by a team of scientists from Australia, Germany, the United States, Canada, South Africa, Spain and France. The object, named after the radio telescope and space coordinates where it was located, as ASKAP J173608.2-321635. The object was discovered as part of an effort to find previously unseen space objects.
Tara Murphy, Wang’s doctoral supervisor and professor at the Sydney Institute for Astronomy, described the radio wave’s behaviour as ‘exceptional’ when it was initially detected.
‘That item was unusual and unique in that it started out invisible, then became bright, faded away and then reappeared,’ Murphy explained.
Researchers got six radio waves over the course of nine months last year, but when they tried to locate them visually, nothing was found. The signal reappeared a few weeks later, after they utilised a radio telescope in South Africa.
Even though it had lasted for weeks in earlier observations at ASKAP, the signal source vanished in a single day, but the team discovered that the source’s behaviour had changed considerably, Murphy reported.
There is no obvious answer as to what is sending the radio waves, but Murphy expects that the riddle will be answered as more powerful telescopes become available in the coming years.