Victor Buso, an Argentine amateur astronomer who was testing his new camera, in a stroke of luck, captured last year for the first time the initial burst of light radiating from the explosion of a massive star.
The light caused by the pressure of a supersonic wave becomes bright when the exploding core of the star first makes contact with the gas found on its surface, causing it to heat up to an extremely high temperature.
It is the first time someone captures an optical light from an ordinary supernova – regarding optical studies not associated with gamma-ray or x-ray bursts. This is uncommon mostly because these types of events occur randomly, and the light they emit is rather short-lived.
UC Berkeley astronomer, Alex Filippenko, followed the discovery with a detailed analysis of the explosion performed at the Lick and Keck observatories. Now, critical observations are being demanded to address the, hopefully, significant new data.
A supernova’s explosion
The bright point of light that’s originated when a star explodes – thus, dies – is what is known as a supernova. According to Space, they can outshine entire galaxies, and even radiate more energy than our Sun in its whole existence. Furthermore, they constitute the primary source of heavy elements in our universe.
Thought as the most massive explosion that occurs in space, it depends on the amount of mass the star has. The portal Space explains, for instance, that our Sun could not turn into a supernova since its mass is not vast enough. This explosion happens about once every 50 years in a galaxy as large as the Milky Way, which means that a star explodes every second approximately in the universe.
Supernovas can be separated into two types. The first one takes place when a runaway nuclear reaction ignites after a star accumulates matter from an adjacent neighbor. The second type is more exciting: it happens when a star collapses under its gravity after running out of nuclear fuel.
Studies demonstrated that supernovas emit vibrations as if they were giant speakers, and produce an audible hum before the explosion takes place. Still, in visual terms, the first time scientists could capture a supernova was in 2008. Back then, the team spotted a rare, extremely bright burst of x-ray that lasted about five minutes, according to astronomer Alicia Soderberg.
It shed itself and the exploded
The amateur astronomer, on September 20, 2016, placed his camera targeting the spiral galaxy NGC 613, estimated to be 80 million years away from Earth. He obtained a series of short-exposure pictures taken from a 16-inch telescope. When he verified the images, almost immediately after he took them, he noted a faint spot of light gleaming near the end of the spiral. It was not visible in the first images he captured.
A colleague of Buso at the Astrophysics Institute of Plata in Argentina, astronomer Melina Bersten, saw the fantastic event her fellow had caught and thought that the chance was one in a million. They immediately named the discovery as “SN 2016gkg,” and contacted an international team of astronomers to ask for further observations. The following research took around two months, but revealed new data about the type of star that exploded, along with information about the explosion itself.
Mr. Filippenko explained they obtained seven spectra – where the light breaks up into its component colors – thanks to telescopes from the University of California’s Lick Observatory, California, and W. M. Keck Observatory, in Maunakea, Hawaii. They found out the supernova was a second type one, specifically a type IIb. The star lost most of its hydrogen envelope, causing the massive explosion.
The supernova type IIb was first observed and identified by astronomer Filippenko in 1987.
The team combined that data and their theoretical models, it estimated that the star long-before-the-explosion mass was at least 20 times the mass of our Sun. If the star lost most of its mass before the explosion, probably to a companion star, the final size would be about 5 solar masses when it finally exploded.
Buso won the cosmic lottery
Mr. Filippenko, addressing the rare and impressive event, claimed amateur astronomer Buso won something he called the cosmic lottery. Buso was complimented by the professional astronomer as he found evidence from the physical structure of a star’s catastrophic death.
“Buso’s data are exceptional. This is an outstanding example of a partnership between amateur and professional astronomers. It’s like winning the cosmic lottery,” said Filippenko.
This study will be published in the journal Nature, and will show the event that Filippenko explains. Scientists and other professional astronomers have long wanted to observe the beginning of a star’s explosion – a type of information that, according to the veteran astronomer, can’t be obtained in any other way.
Source: UC Berkeley