Liked on YouTube: What Is A Hypernova?

What Is A Hypernova?
In a galaxy not so far away - only 25 million light-years - astronomers have found what looks like the remnants of strange celestial explosions called hypernovae. "Hypernovae are possibly the most powerful explosions in our Universe since the Big Bang," said Q. Daniel Wan* an astrophysicist at Northwestern University. A hypernova is a highly energetic supernova thought to result from an extreme core collapse scenario in which a massive star of more than 30 solar masses collapses to form a rotating black hole emitting twin energetic jets and surrounded by an accretion disk. This collapse happens so quickly that the outer parts of the star are unaware of what has taken place, and the star is subsequently exploded by vigorous winds of newly-formed Nickel-56 blowing off the accretion disk, and shock waves produced as the jets plough through the stellar material. The hypernova, whose luminosity is powered by the radioactive decay of Nickel-56, is the result of the explosion of the star. ------------------------------------------------------------------------------------------- Subscribe for more videos:https://www.youtube.com/c/InsaneCuriosity?sub_confirmation=1? Business Enquiries: Lorenzovareseaziendale@gmail.com ------------------------------------------------------------------------------------------- This model for the formation of a hypernova also predicts that these objects should be accompanied by a gamma ray burst or GRB. Although the mechanism to form the gamma rays is still a matter of debate, it is thought that they are produced through internal collisions within the jet itself. Whatever the actual mechanism, the gamma rays are beamed into a narrow cone along the direction of motion of the jet, and are visible to us only if the jet is pointed in our direction. Astronomers estimate that for every GRB we observe, there are several hundreds more we don’t see, those which are oriented in directions away from us. Conclusive evidence for this hypernova-GRB connection was obtained only recently. Although there were many cases where the light curve of the prototype hypernova, SN1998bw, could be fitted to the light curve decay of gamma ray burst optical transients associated with GRBs, it was not until astronomers clearly observed the spectrum of a hypernova within the spectrum of an optical transient that the connection was firmly established. In 1998 one explosion occurred that revolutionized our understanding of the stellar calamity that gives rise to a GRB. In a nearby spiral galaxy SN 1998bw appeared. It bore many unusual features for membership of the Type Ic fraternity. Although clearly belonging to the class of supernovae deficient in hydrogen and helium, this explosion showed very broad emission features and unusually strong radio emission, both characteristics of material moving at a sizable fraction of the speed of light. Essentially simultaneously, GRB 980425 irradiated Beppo-SAX, triggering the hunt for an afterglow. Measurements of the emission from the GRB suggested that at most 10 to the power minus 5 solar masses of material was ejected in the jets. Additionally, the peak gamma ray emission was four orders of magnitude less than many of the previously observed “cosmological” bursts. Overall, this was a fairly wimpy gamma ray burst. Meanwhile, SN 1998bw displayed a number of peculiarities that led some to quickly suggest that this explosion might be more than just spatially coincident with the GRB. They might be causally related. In terms of its peak luminosity SN 1998bw would be regarded as rather underwhelming by today’s standards, clocking in with a peak absolute magnitude of minus 19.5, but at the time this was many times more luminous than the majority of observed Type Ic events. However, given that this modestly high luminosity was driven solely by matter produced and ejected in the explosion itself, the implication was that the explosion was unusually energetic. Two pieces of evidence were important here. The first was the high ejecta velocities, while the second was the above average peak luminosity. Together these implied that 0.5–0.7 solar masses of radioactive nickel had been synthesized – ten times that seen in other core-collapse supernovae – and more in line with thermonuclear Type Ia events. ------------------------------------------------------------------------------------------- "If You happen to see any content that is yours, and we didn't give credit in the right manner please let us know at: Lorenzovareseaziendale@gmail.com and we will correct it immediately" "Some of our visual content is under a Attribution-ShareAlike license. (https://ift.tt/1jttIpt) in it’s different versions such as 1.0, 2.0, 3,0 and 4.0 – permitting comercial sharing with attribution given in each picture accordingly in the video." Credits: Ron Miller Credits: Nasa/Shutterstock/Storyblocks/Elon Musk/SpaceX/Esa Credits: Flickr #InsaneCuriosity
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