ASASSN-18bt exhibited some unusual behavior to surprise researchers.

Images of the newly discovered supernova ASASSN-18bt may change our perspective about the origin of the universe. Six images were captured in total: Three before the explosion and three were taken after that. The images are credited to the All-Sky Automated Survey for Supernovae (ASAS-SN) project, the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), and the Kepler Space Telescope of NASA.

A team of international scientists discovered this supernova under the leadership of Tom Holoien and Maria Drout from Carnegie Mellon and Ben Shappee of University of Hawaii. The actual mechanism that led to this stellar explosion is still unknown because to gather exact information, the scene must be viewed during the act. Typically, such supernovae occur when a white dwarf star explodes.

A white dwarf star is the residual dead core left behind when a massive star ‘dumps’ its fuel. This means that this type of supernova occurs when a massive star runs out of nuclear-fusion fuel in its core. The star then begins to collapse, which compresses protons and electrons together and converts them into neutrons. In the case of ASASSN-18bt, the light distribution displayed odd behavior, the cause of which is still a mystery.

Decades ago, theorists have predicted that a burst of X-rays would be produced whenever a supernova is visible. The only problem is that there is virtually no way to know when a supernova is visible. Therefore, ASASSN-18bt was caught by pure luck. Shappee mentioned that by saying,

“ASASSN-18bt is the nearest and brightest supernova yet observed by Kepler, so it offered an excellent opportunity to test the predominant theories of supernova formation. The Kepler light curve is amazing. We can probe the explosion just hours after it happened. We are finding that supernovae explosions are more complicated than we previously thought, and that’s half the fun”.

The data from ASA-SN, Kepler, Pan-STARRS, and ATLAS telescopes were combined, and the result was unusual. During its initial days, ASASSN-18bt exhibited odd behavior. Usually, when a supernova explodes, there is a gradual increase in light emission. However, ASASSN-18bt seemed to release some unknown and additional emission. A theory suggests that the additional emission may have occurred when the exploding white star collided with a nearby star. Tom Holoien elaborated that and said,

“While the steep increase in ASASSN-18bt’s early brightness could indicate that the explosion collides with another star, our follow-up data don’t fit predictions for how this should look. Other possibilities, such as an unusual distribution of radioactive material in the exploded star, are a better explanation for what we saw. More observations of ASASSN-18bt and more early discoveries like this one will hopefully help us differentiate between different models and better understand the origins of these explosions.”

The unusual behavior supports a recent hypothesis by Maxmillian Stritzinger of Aarhus University. He theorized that there may be two types of supernovae. Ones that show early emission and other that do not. Shappee agreed that the supernovas are getting more and more complicated and as a result, more mysterious. The space telescopes can be used collectively to find more supernovae and unravel the mystery of supernovae.

ASAS-SN, Pan-STARRS, ATLAS, and a few other telescopes are monitoring the sky every night searching for supernovae. They remain visible for months or sometimes even years. Having said that, scientists need to view the supernova as it forms in order to get desired data. Dan Milisavljevic, an Assistant Professor of Physics and Astronomy at Purdue University described that in the following words:

“We haven’t seen an explosion of this type, at such a late timescale, remain visible unless it had some kind of interaction with hydrogen gas left behind by the star prior to the explosion. But there’s no spectral spike of hydrogen in the data — something else was energizing this thing.”

Scientists all around the world are excited at the prospect of learning more about supernovae and many rushed to study the data as soon as the news about ASASSN-18bt spread. However, there is no final conclusion about this specific supernova as scientists have different thoughts about this event. One thing is for sure that this discovery has urged all the theorists to explore all the possible explanations to answer the ever-increasing number of questions about supernovae.