According to Science Alert, astronomers have identified a mysterious breed of stars that are destined to create epic supernovas
Supernovas are the result of massive stars dying. When a star’s core becomes so dense that protons and electrons start to form neutrons, it collapses into a neutron star. This death spectacle can be brighter than an entire galaxy in the night sky.
Astronomers predict that about a third of all massive supernova progenitors are hydrogen-poor. This is because many supernovas are mysteriously hydrogen-free.
Some astronomers believe that the red supergiant Betelgeuse, which is about 725 light-years away, is destined to end its life in a supernova blast. They think the star’s sudden dimming may be a pre-supernova event that happened around 1300.
A large number of supernovas are mysteriously devoid of hydrogen – suggesting that there must also be a significant population of hydrogen-poor stars from whence such supernovas come. In fact, astronomers predicted that around a third of all massive supernova progenitors must be hydrogen-poor.
According to theory, stripped-envelope supernovas, as these hydrogen-poor supernovas are known, are produced by binary stars. We’ve seen stars in close binary systems slurping material off each other before
According to ScienceAlert, the lack of hydrogen in many supernovas suggests that there must be a large population of hydrogen-poor stars. Astronomers predict that about a third of all massive supernova progenitors are hydrogen-poor
Here are some reasons why stars can be hydrogen-poor:
- Stellar evolution Hydrogen deficiency can be caused by stellar evolution. As a star evolves, it consumes hydrogen through nuclear fusion and explosive processes can remove hydrogen layers.
- Binary star systems In binary star systems, one star can pull material from its companion star. This can result in a helium-rich star with little hydrogen.
- Envelope stripping In binary systems, a companion star can strip the hydrogen envelope from a massive star.
Hydrogen-poor supernovas are also known as stripped-envelope supernovas
Supernovae add enriching elements to space clouds of dust and gas, further interstellar diversity, and produce a shock wave that compresses clouds of gas to aid new star formation. But only a select few stars become supernovae. Many stars cool in later life to end their days as white dwarfs and, later, black dwarfs.
According to a ScienceAlert article, astronomers have identified a group of intermediate-mass, stripped helium stars that are destined to become hydrogen-poor supernovae.
Astronomers have long known that Type Ic supernovas are deficient in hydrogen and helium. They originally believed that these stars shed this material in a strong wind before exploding.
In 2018, astronomers used NASA Hubble Space Telescope archival data to find the progenitor to a specific type of exploding star. This type of supernova is called a Type Ic, and is thought to detonate after its massive star has shed or been stripped of its outer layers of hydrogen and helium.
In 2022, NASA’s Hubble Space Telescope discovered a companion star that survived the explosive death of its partner. This discovery is a first for a particular type of supernova, where the star was stripped of its entire outer gas envelope before exploding.
The most massive stars are the brightest stars, and they are the most likely to go supernova. Stars that are more than 1.4 times the mass of the Sun are more likely to explode in a supernova. This limit is called the Chandrasekhar limit, after the Indian physicist who discovered it
The most massive B-type main-sequence stars and O-type stars can go supernova. A and F-type stars will likely become a red giant and then a planetary nebula and white dwarf, like the Sun.
Supernovae occur during the final stages of a massive star’s evolution or when a white dwarf is triggered into runaway nuclear fusion. The original object, called the progenitor, either collapses to a neutron star or black hole, or is completely destroyed to form a diffuse nebula.
The most common type of supernova is a Type II-plateau, so called because the luminosity stays nearly the same for months.
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