Danny Milisavljevic, an expert on star life cycles, worked with a team of researchers and an AI program to uncover and identify one of the most luminous, energetic events ever observed in the universe.
Newswise — WEST LAFAYETTE, Ind. –
A far-off star, undergoing a fiery and dramatic demise, was ripped apart by a supermassive black hole in a neglected area of the heavens. Rather than blazing across the night sky, igniting legends and initiating civilizations, this was one of the most brilliant, vigorous, enduring transient entities. Instead, astronomers, functioning as cosmic detectives, unearthed proof of the star's death convulsions, which had been concealed undetected for years within a collection of telescope data gathered by computers.
"Such a notion is ludicrous. Even if you were to magnify a typical supernova by a factor of one thousand, we would still fall short of the luminosity displayed here - and supernovas are recognized as some of the most radiant entities in the heavens," declared Danny Milisavljevic, an associate professor of physics and astronomy in the College of Science at Purdue University. "I have never witnessed a more dynamic phenomenon than this."
Within the realm of astronomy, the most energetic entities are often the most radiant. Milisavljevic, a specialist in the life cycles of stars, particularly their demise, emphasized that the data indicates an exceedingly aberrant observation.
When it was initially detected, the object was assigned a random moniker, like all other entities under scrutiny. It was bestowed with the appellation ZTF20abrbeie, but astronomers have endearingly nicknamed it "Scary Barbie." The "Barbie" portion of the name stems from its alphanumeric identifier, while "scary" is derived from its alarming characteristics, as emphasized by Milisavljevic: "It deviates so drastically from the norm that it's rather frightening!"
This entity is classified as a transient, a phenomenon in the sky that either emerges and vanishes or undergoes significant alterations over the span of hours or days rather than centuries or millennia. In a recent study that will be published in The Astrophysical Journal Letters, Milisavljevic, along with his graduate student Bhagya Subrayan and their research team, scrutinized the data and inferred that the vivid, long-lasting transient is, in fact, a black hole engulfing a star. Subrayan's research is centered on the analysis of extensive sky survey data.
"Our hypothesis is that a tremendously massive black hole drew in and tore apart a star," explained Subrayan. "The gravitational forces around a black hole, known as tidal disruption, fragment other objects, causing them to become elongated like spaghetti - a process aptly named 'spaghettification.' In this instance, we believe that's precisely what transpired, but on an incredibly protracted timescale: an immensely colossal black hole tearing apart a massive star. The duration of this phenomenon is unparalleled, generating the most radiant transient ever witnessed in the cosmos."
Given Scary Barbie's remarkable luminosity and noteworthy properties, why did its discovery only take place recently despite initial observations dating back to 2020 as indicated by the datasets?
The reason for the belated detection of Scary Barbie is due to its remote location and its position in an unobserved region of the sky, despite its luminosity. However, Milisavljevic's lab was able to identify this anomaly using their AI system, the Recommender Engine For Intelligent Transient Tracking (REFITT). REFITT sifts through data obtained from a variety of telescopes worldwide, including the Zwicky Transient Facility at the Palomar Observatory in California, to detect unusual celestial events.
Milisavljevic explained that REFITT is capable of analyzing vast amounts of data and identifying potential areas of interest for further investigation. In this case, the system was able to pinpoint Scary Barbie as a unique and compelling phenomenon. While computers excel at recognizing patterns and identifying specific criteria, anomalous objects like Scary Barbie can be particularly difficult to detect since there are no templates or preconceived notions to guide the search. As a result, this exceptional object remained unnoticed until the advanced capabilities of REFITT brought it to the attention of astronomers. Milisavljevic added that Scary Barbie had been hiding in plain sight within the publicly available data for several years.
After the team and REFITT had identified Scary Barbie as an intriguing research subject, they utilized data from additional telescopes, such as the Lick Observatory in California and the W.M. Keck Observatory in Hawaii. Spectrographic analysis performed by these telescopes allowed the team to categorize the peculiar phenomenon reported by the data.
Not only is Scary Barbie significantly brighter and more energetic than any previously recorded transient, but it is also exhibiting an unprecedented duration. Most transients typically last for several weeks or months, yet Scary Barbie has persisted for over 800 days – a duration of over two years – and current data suggests that it will remain visible for many more years to come.
The spaghettification of the massive star during the actual event may have been of much shorter duration, but due to the extreme distance of the transient, the laws of relativity cause a time dilation effect, slowing down the light's travel time to human observers and making it appear to last almost twice as long as it actually did.
Milisavljevic remarked, "There are limited entities in the cosmos that possess such immense power and persistency. Observations like this widen our understanding of the fact that there are still enigmas and marvels in the universe, and we are yet to unveil them - phenomena that no one has witnessed before."
This research was funded in part by the National Science Foundation.
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