Summary
Type Ia supernovae, a bright and long-lasting brand of stellar explosion, play a vital role in cosmic chemical manufacturing, forging in their fireballs most of the iron and other metals that pervade the universe. The explosions also serve as “standard candles,” assumed to shine with a predictable brightness. Their brightness as seen from Earth provides a cosmic yardstick, used among other things to discover “dark energy,” the unknown force that is accelerating the expansion of the universe. Astronomers have long thought that the blasts come from white dwarfs, burnt out stars once like our Sun, reignited after stealing material from a companion red giant. But evidence is mounting that other mechanisms may be causing white dwarfs to explode, making their standard candle status a puzzle.
https://science.sciencemag.org/content/368/6495/1046
Ref:
Eerder ‘yardstick’ probleem.
Eerder beeld en Type Ia toelichting.
The VLT Measures the Shape of a Type Ia Supernova
The explosion of a white dwarf star
In the most widely accepted models of Type Ia supernovae the pre-explosion white dwarf star orbits a solar-like companion star, completing a revolution every few hours. Due to the close interaction, the companion star continuously loses mass, part of which is picked up (in astronomical terminology: “accreted”) by the white dwarf.
A white dwarf represents the penultimate stage of a solar-type star. The nuclear reactor in its core has run out of fuel a long time ago and is now inactive. However, at some point the mounting weight of the accumulating material will have increased the pressure inside the white dwarf so much that the nuclear ashes in there will ignite and start burning into even heavier elements. This process very quickly becomes uncontrolled and the entire star is blown to pieces in a dramatic event. An extremely hot fireball is seen that often outshines the host galaxy.
https://www.eso.org/public/news/eso0325/
https://nl.wikipedia.org/wiki/Supernova
https://en.wikipedia.org/wiki/Supernova
