© NASA, ESA, and A. Field (STScI)
The progenitor of a Type Ia Supernova.
Type Ia supernovae are an important tool for modern astronomy. They are thought to occur when a white dwarf star captures mass beyond the Chandrasekhar limit, triggering a cataclysmic explosion. Because that limit is the same for all white dwarfs, Type Ia supernovae all have about the same maximum brightness. Thus, they can be used as standard candles to determine galactic distances. Observations of Type Ia supernova led to the discovery of dark energy and that cosmic expansion is accelerating.
While these supernovae have revolutionized our understanding of the universe, they aren't quite as standard as we first proposed. Some, such as SN 1991T are much brighter, while others, such as SN 1991bg are much dimmer. There is also a variation known as Type Iax, where the white dwarf isn't completely destroyed by the explosion. We can generally take these variations into account when calculating stellar distances, but it would be good to have a better understanding of the mechanism behind their maximum brightness.
According to theoretical models,
the maximum brightness of a Type Ia supernova depends upon the mass and central density of the white dwarf before it explodes. But how could these values be measured? After all, we typically only discover these stars after they explode. Fortunately, a new study in
The Astrophysical Journal Letters shows how it can be done.
Comment: A recent study revealed that galaxies throughout our universe are surprisingly similar, and this may be because the same forces involved in their formation are, rather than working in isolation, in some way connected:
- Why the sun's atmosphere is hundreds of times hotter than its surface
- Milky Way not unusual, surprising astronomers
- Magnetic fields may be secret to planetary formation, supercomputer model reveals
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