Why are Type Ia supernovae considered invaluable for measuring cosmic distances?

Answer

They possess remarkably consistent peak brightness because they always occur near the same mass limit.

The utility of Type Ia supernovae as 'standard candles' in cosmology stems directly from the physical process that triggers them. Since these explosions require the white dwarf to accrete mass until it hits the specific Chandrasekhar Limit of $1.4 M_{ extregistered extsuperscript{ extcircled}O}$, the initiating conditions for the thermonuclear detonation are virtually identical across all Type Ia events. This consistent starting point means that the resulting explosion yields a remarkably uniform maximum or peak brightness. By comparing the known intrinsic peak luminosity of a Type Ia supernova with its observed apparent brightness from Earth, astronomers can accurately calculate the distance to the host galaxy, irrespective of other variables.

Why are Type Ia supernovae considered invaluable for measuring cosmic distances?

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