Question

Our Sun is a type G2V star on the main sequence. As it ages and uses up its fuel we expect it to ________?

1) expand into a red giant
2) collapse into a white dwarf
3) explode in a supernova
4) transform into a black hole

Answer 1

A G2V star like the Sun will expand into a red giant, undergo a helium flash, and eventually exhaust its fuel, becoming a red giant again before shedding its outer layers and collapsing into a white dwarf.

Step-by-step explanation:

Evolution of a G2V Main Sequence Star Like the Sun

As a G2V main sequence star like our Sun ages and uses up its hydrogen fuel, we can predict the following stages of its evolution:

1. The star will expand into a red giant, becoming larger, redder, and more luminous as the helium core contracts and hydrogen fuses in a shell outside the core.
2. Following a helium flash, the star undergoes a readjustment leading to a period of stability while helium is fused into carbon and oxygen.
3. The star eventually exhausts its helium and becomes a red giant again, this time with a core supported by electron degeneracy pressure as it can no longer sustain fusion.
4. The star sheds its outer layers, creating a planetary nebula, and the exposed hot inner core becomes a white dwarf.

The Sun-like star will move across the Hertzsprung-Russell (H-R) diagram towards the white dwarf region, becoming cooler and less luminous over time, until it fades away.