Liverpool Telescope captures the earliest spectra of a Type Ia supernova
Type Ia supernovae (SN Ia’s) are incredibly bright, but are so similar to each other that astronomers use them as standard candles with which to measure the distance of galaxies. It was thought that they occur in close-orbiting binary star systems, where a dense, compact white dwarf star made of carbon and oxygen is sweeping up material from a bloated companion star. As it acquires more material, it grows towards the limit of how massive a white dwarf can be - thought to be around 1.4 times the mass of the Sun. When it reaches that limit, nuclear reactions restart on the surface of the white dwarf and causes it to undergo a massive supernova event that ejects material back into the cosmos. The mass of the white dwarf drops again and once the supernova has died down, it resumes its previous existence. However, as long as material is being transferred onto the white dwarf, the pattern will repeat.
The recent observations, and the LT spectra in particular, confirmed that the star from which the supernova originated was made of carbon and oxygen, and that it was indeed around 1.4 solar masses. This is the strongest evidence yet that the previous view of what causes Type Ia supernova was indeed correct.