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So a supernova with a measured redshift z = 0.5 implies the universe was 1 / 1 + 0.5 = 2 / 3 of its present size when the supernova exploded. In the case of accelerated expansion, a ¨ {\displaystyle {\ddot {a}}} is positive; therefore, a ˙ {\displaystyle {\dot {a}}} was smaller in the past than today.
Calcium-rich supernovae are a rare type of very fast supernova with unusually strong calcium lines in their spectra. [69] [70] Models suggest they occur when material is accreted from a helium-rich companion rather than a hydrogen-rich star. Because of helium lines in their spectra, they can resemble type Ib supernovae, but are thought to have ...
SN 1054 remnant (Crab Nebula)A supernova is an event in which a star destroys itself in an explosion which can briefly become as luminous as an entire galaxy.This list of supernovae of historical significance includes events that were observed prior to the development of photography, and individual events that have been the subject of a scientific paper that contributed to supernova theory.
NASA's James Webb Space Telescope (JWST) has captured photos of one of the earliest supernovas ever seen, with features appearing like grains and knots found in a cut of wood. "Once upon a time ...
Hypernovae are thought to be supernovae with ejecta having a kinetic energy larger than about 10 45 joule, an order of magnitude higher than a typical core collapse supernova. The ejected nickel masses are large and the ejection velocity up to 99% of the speed of light .
A nova, a rare astronomical event, could be visible soon. It won't last long, and it won't occur again for several decades. How to see it in 2024.
The expansion of the universe is the increase in distance between gravitationally unbound parts of the observable universe with time. [1] It is an intrinsic expansion, so it does not mean that the universe expands "into" anything or that space exists "outside" it.
The total energy of typical gamma-ray bursts has been estimated at 3 × 10 44 J, – which is larger than the total energy (10 44 J) of ordinary supernovae (type Ia, Ibc, II), [103] with gamma-ray bursts also being more powerful than the typical supernova. [104] Very bright supernovae have been observed to accompany several of the nearest GRBs ...