Stellar Death of High Mass Stars

High mass stars can go through several additional stages of thermonuclear reactions instead of just stopping at helium burning. This is only possible because the star has more gravity pulling it together and has more pressure at its core. Heavy-nucleus fusion can result as the temperatures are high enough to fuse heavy elements together as the nuclei can then travel fast enough and overcome their mutual electrical repulsion and fuse together.

Each stage of thermonuclear reactions in a high-mass star helps to trigger the succeeding stage as it ‘ignites’ the ash of the previous stages and generates a new shell of material. The processes of thermonuclear reactions can take place at the same time in several shells, releasing energy quickly that the outer layers expand rapidly. This results in a super giant star, whose luminosity and size may be many dozens of times their original.

After the last stage where silicon is burnt, the star has now a iron-rich core and this signals of an imminent violent explosion.

While most stars become planetary nebula at the end of their lives, stars of more than 8 solar masses when they became main-sequence stars will die in fiery explosions.

Other types of supernova

An accreting white dwarf in a close binary system can also become a supernova when carbon burning causes explosions throughout this degenerate star.

Classification of Supernova

Ia- These supernovae are produced by accreting white dwarfs in close binaries. They have spectra that have strong absorption line of ionized silicon.

Ib- These supernovae lack the ionized silicon line but have a strong helium absorption line.

Ic- These supernovae lack the ionized silicon line and do not have a strong helium absorption line.

These are created by the deaths of massive stars like Type Ib and Ic. They occur when the star has lost a substantial part of its outer layers before exploding.

Life Cycles of Stars | Diffuse Nebula | Main-Sequence Stars | Red Giants after Main-Sequence | Death of a Low Mass Star | Death of a High-Mass Star | Star Families | Magnitude Scale | Measuring Stellar Distances | Classification of stars | Wien's Law and Stefan-Boltzmannn Law for a Blackbody | Stellar Spectra