Star explosions, known as supernovae, can be so bright that they overshadow their home galaxies. It takes months or years for them to disappear, and sometimes the gaseous remnants of an explosion collapse into hydrogen-rich gas and become bright again. In this regard, astronomers have long been tormented by the question – are they able to remain luminous without any outside interference? Dan Milisavlevich, assistant professor of physics and astronomy at Purdue University, is confident that this is possible. He cites the explosion of SN 2012au as an example:
“Previously, we could not even imagine that an explosion of this type would remain visible at such a late period of time, given the fact that it did not have any interaction with the hydrogen gas left by the star before the explosion. However, the spectral data showed absolutely no hydrogen bursts, making this object even more mysterious. '
As large stars explode, their interiors collapse to the point where all of their particles become neutrons. If the resulting neutron star has a magnetic field and rotates fast enough, it could turn into a pulsar nebula. This is most likely what happened with SN 2012au. The astronomers' findings were published in The Astrophysical Journal Letters.
“We know that supernova explosions produce these types of rapidly rotating neutron stars, but we have never seen direct evidence of these events in such a unique period,” Milisavlevich said. “This is a key moment when the pulsar nebula is bright enough to act as a light bulb to illuminate the blast's outer emissions.”
SN 2012au was already known to be quirky and strange. Although the explosion was not bright enough to qualify as a 'superluminal' supernova, it was extremely energetic and durable and dimmed on an equally slow light curve. According to Milisavlevich, if researchers continue to track sites of extremely bright supernovae, they may see other similar transformations.
“If there really is a pulsar or magnetic wind nebula at the center of an exploding star, it could push out and even accelerate gas,” he said. “If we go back to some of these events in a few years and take careful measurements, we can watch the oxygen-rich gas accelerate from the explosion.”
Superluminal supernovae are a controversial topic in transition astronomy. They are potential sources of gravitational waves and black holes, and astronomers believe they may be associated with other types of explosions, such as gamma-ray bursts and fast radio signals. Researchers now want to understand the fundamental physics behind them, but they are difficult to spot because they are relatively rare and only observed from Earth. It is believed that only the next generation of telescopes, which astronomers have called 'extremely large telescopes', will be able to observe these events in detailed details.
'This is a fundamental process in the universe. We would not be here if this did not happen, ”Milisavlevich said. “Many of the elements necessary for life come from supernova explosions – calcium in our bones, the oxygen we breathe, iron in our blood – I think it is very important for us as citizens of the universe to understand this process.”
