Hubble discovers a doomed star and dodges

Stars are like people: they send their dazzling light across the Cosmos for a little while, but they don’t last forever in the universal tragicomedy of our existence. Supernovae herald the fatal explosions of massive stars that have reached the end of that long stellar path, having burned off the necessary supply of nuclear fusion fuel, and have perished brilliantly and beautifully, explosively screaming into oblivion. One of the ways astronomers look for clues, hinting at how these massive stars explode, is to hunt for what is called the progenitor star of the supernova. To carry out their search, astronomers carefully examine images from archival telescopes and try to determine the precise location and identity of the progenitor star before bursting to pieces. In November 2018, for the first time, a team of astronomers at the California Institute of Technology (Caltech) in Pasadena announced that they had likely discovered such stellar progenitor for a class of supernova known as Type Icpronounced “one-C”). Of all the supernova classes, this is the only one that did not have a known stellar. progenitor until its discovery. For this reason, astronomers viewed his identification as a kind of Holy Grail.

Tea Type Ic supernova, nicknamed SN 2017, was first discovered in May 2017 by astronomers using the Tenagra Observatories in Arizona. It is located in a spiral galaxy called NGC 3938, which is located about 65 million light years from Earth. Caltech astronomers were able to successfully track this supernova progenitor using NASA archive images Hubble Space Telescope (HST), obtained in 2007.

“An alert was sent when the supernova was initially found. You can’t sleep once that happens and you have to mobilize to try to find the one. progenitor to the explosion. A few weeks after the supernova was discovered, we found a candidate that used both new and archive files. Hubble images. The new images were essential to identify the candidate progenitor location, “noted Dr. Schuyler Van Dyk on a November 15, 2018 JPL press release. Dr. Van Dyk is a staff scientist at IPAC, which is a data and science center located at Caltech.

Tea progenitor turned out to be a very hot and luminous star, and is believed to be a single-mass star 48 to 49 times the mass of the sun or a massive binary system in which the star that went supernova weighed between 60 and 80 times the mass mass of our Sun.

Writes Supernovae Ic

Type Ic supernovaeand his close cousins Type Ib supernovae, are classifications of supernovae that result from the explosive collapse of the nucleus of massive stars. These doomed stars have shed, or have been more gently stripped of their outer shell of hydrogen gas. When Type Ic and Type Ib supernovae are compared to Type Ia supernovae, do not show the silicon absorption line. In comparison with Writes Ib, Type Ic supernovae they are believed to have lost more of their original gaseous envelope, including most of their helium. Astronomers often refer to the two types as “Supernovae stripped from core collapse”.

All stars, regardless of their mass, produce energy through the process of nuclear fusion of atomic elements, which creates heavier elements from lighter elements. Unlike our relatively small Sun, the most massive stars contain enough mass to fuse elements that have an atomic mass greater than hydrogen and helium, albeit at increasing temperatures and pressures. This increase results in a shorter “life” for massive stars. Small stars, like our Sun, “live” on the branch of the Hertzsprung-Russell diagram of stellar evolution for about 10 billion years. In dramatic contrast, massive stars “live” fast and “die” young. The more massive the star, the shorter its “life”. A strong star fuses increasingly heavy atomic elements, starting with hydrogen and helium, and then progressing through the familiar Periodic table until an iron nickel core is formed. Because nuclear fusion of iron or nickel does not produce net energy production, no further fusion can occur, rendering the nickel-iron core of the massive doomed star inert. Due to the lack of energy production, the necessary external thermal is created. Pressure to keep the heavy star bouncing against the relentless inward pull of its own gravity, the core wrinkles. When the compacted mass of the inert iron and nickel core exceeds what is called Chandrasekhar boundary 1.4 solar masses, radiation pressure I can’t counter gravitational compression, and a cataclysmic implosion of the core occurs within seconds. At this point, lacking the support of the now imploded inner core, the outer core of the ancient massive star collapses inward under the ruthless force of gravity and reaches a speed of up to 23% of the speed of light. The sudden and dramatic compression increases the temperature of the inner core up to 100 trillion Kelvins. The collapse of the inner core is stopped by neutron degeneration, resulting in the implosion to bounce and bounce out. The energy from the expanding shock wave disrupts the overlying stellar material and accelerates it to escape speed. Horrible, brilliant Type II supernova it happens, and where once there was a massive star, there is no star anymore. Depending on the strong progenitor mass of the star, the memory it leaves behind to remind the Universe of its previous existence will be a dense one, the size of a city neutron star or a stellar mass black hole.

The little stars go to their inevitable Grand finale differently. Type Ia supernovae, unlike the core collapse Type II supernovae, do not originate from the funeral pyre of a massive progenitor star. Type Ia supernovae are the catastrophic remains of small stars, like our Sun, that have perished to become a type of dense stellar relic called white dwarf. Our Sun will never perish in the terrible beauty born of a Type Ia explosion. This is because our Sun is a lone star. However, when small stars of the mass of our Sun inhabit a binary system with another star still alive, it is a party ready to happen. If the dense, vampire white dwarf Relentlessly gravitationally sucking up the material from his fellow star, he pays for his crime by “becoming critical.” I mean, the killer white dwarf It steals enough mass from its companion to reach critical mass to blow itself apart, just like its more massive stellar relative. Alternatively, a Type Ia supernova can also occur when a duo of white dwarfs, composing a binary system, they explode each other. When this happens, it also results in a frightening Type Ia supernova explosion.

Putting together how each of these types of supernovae (Type II, Type Ib, Type Ia, and Type Ic) occur provides a much better understanding of how the most massive stars in the Universe evolve.

Discovering an elusive and doomed stellar Progenitor

Type Ic supernovae they occur with the most massive stars. But we were surprised by how massive this one appears to be, and especially by the possibility of a massive double star system like the one. progenitor. Although there have been theories for the past three decades that Type Ic supernovae could be the very massive single star explosions, the most recent alternative theories point to lower mass stars in binary systems as the origin of these explosions, “explained Dr. Van Dyk on November 15, 2018 Caltech press release.

Type Ib and Type Ic differs from Type II because its stellar parents they lose their outer sheaths of material that surround their central cores before going supernova. Type Ib and Ic they also differ slightly from each other in chemical composition.

“The origins of such explosions are relevant to the entire astronomical community, not just supernova researchers. The results have implications for ideas, from star formation to stellar evolution and feedback in the galaxy,” commented Dr. Ori Fox on November 15, 2018. Caltech press release. Dr. Fox is a Support Scientist at the Space Telescope Science Institute (STScI) in Baltimore, Maryland.

Dr. van Dyk continued to note in the same Press release that “astronomers have been trying to find this progenitor for about 20 years. Humans wouldn’t be here without supernovae– they make the chemical elements we are made of. “

The astronomers also commented that they should be able to confirm with certainty whether they have identified the correct progenitor to the Type Ic explosion in a few years, using Hubble or the next James Webb Space Telescope, planned to launch in 2021. As the supernova dims as predicted, astronomers will have a clearer view of the region around it. If the luminous progenitor The candidate was correctly identified in the stock images, then it will have disappeared and should not be detected in the new images. If scientists still see the candidate progenitorThat means it was misidentified and some other hidden star was the real culprit for the cataclysmic explosion.

In memory of Mark.