Question

The peak brightness of type ii sne is in general several magnitudes fainter than thatof type ia sne. But type ii-p sne show a large dispersion in their maximum brightness.However, th

Answer 1

A type Ia supernova (read "type one-a") is a type ofsupernova that occurs inbinary systems (two starsorbiting one another) in which one of the stars is awhite dwarf. The other star can be anything from a giant star to an even smaller white dwarf.[1]Physically, carbon–oxygen white dwarfs with a low rate of rotation are limited to below 1.44 solar masses (M☉).[2][3] Beyond this, they reignite and in some cases trigger asupernova explosion. Somewhat confusingly, this limit is often referred to as the Chandrasekhar mass, despite being marginally different from the absoluteChandrasekhar limit whereelectron degeneracy pressure is unable to prevent catastrophic collapse. If a white dwarf gradually accretes mass from a binary companion, the general hypothesis is that its core will reach the ignition temperature forcarbon fusion as it approaches the limit.However, if the white dwarf merges with another white dwarf (a very rare event), it will momentarily exceed the limit and begin to collapse, again raising its temperature past the nuclear fusion ignition point. Within a few seconds of initiation of nuclear fusion, a substantial fraction of the matter in the white dwarf undergoes a runawayreaction, releasing enough energy (1–2×1044 J)[4] to unbind the star in a supernova explosion.[5]This type Ia category ofsupernovae produces consistent peak luminosity because of the uniform mass of white dwarfs that explode via the accretion mechanism. The stability of this value allows these explosions to be used asstandard candles to measure the distance to their host galaxies because the visual magnitude of the supernovae depends primarily on the distance.In May 2015, NASA reported that the Keplerspace observatoryobserved KSN 2011b, a type Ia supernova in the process of exploding. Details of the pre-nova moments may help scientists better judge the quality of Type Ia supernovae as standard candles, which is an important link in the argument for dark energy.[6]