Stellar Evolution - Edexcel IGCSE Science (Double Award)

These flashcards cover key terms related to stellar evolution, star life cycles, and classification of stars, essential for understanding concepts in physics.

Nebula defintion and how is it formed?

A giant cloud of gas and dust where stars form.

A nebula is mostly hydrogen and helium gas, gravitational attraction pulls the dust and gas together → to than therefore forms a protostar.

Protostar

A hot ball of gas formed from the gravitational pull of a nebula.

Explain Protostar → Main sequence

As the mass of the protstar increases so does the inwards force due to gravity. When temperautres and density are high enough nuclear fusion can start → this outward radiation pressure due to fusion balances the inward pull of gravity. Therefore starting the stable period of the main sequence star.

Main Sequence → Red Giant

Hydrogen eventually fuses into helium and the temperature is not high enough to fuse helium into heavier elements. Therefore, the outwards pressure decreases and gravity takes over and the start begins to collapse.

White + Black Dwarf

The center of the small dense bright core still remains after all the outer layers have drifted out. And than the light eventually fades into a black dwarf

Main Sequence → Red Supergiant

A later stage where a massive star exhausts its hydrogen fuel, leading to its expansion and cooling. During this phase, the star can fuse elements heavier than helium and when temperature is high again

Red supergiant → Supernova

Once helium supply runs out, fusion will not stop because red supergiants contract and fusion reactions only stop after a iron core is formed.

Supernova→ Neutron Star

when the outer layers of the star collapse under gravity for a final time and bounce of the iron core resulting in a explosion known as the supernova.

these outer layers of the supernova are ejected out into space, leaving behind a small,dense core in the center. A neutron star

Supernova → Black Hole

Black holes have high gravitational field and are the densests objects in the Universe.

List the color from hottest to coolest of a star

Hottest→ Coolest = Blue →White → Yellow → Orange → Red

Low mass stars are cooler and therefore appear?

Yellow or red

High mass stars are hotter and appear

blue or white

Red giant → Planetary Nebula

When helium supply in the core runs out and fusion stops for good, the outward pressure from fusion stops and the gravitational force takes over and compresses the inner layers of the star. and the out layers drift outward to form a planetary nebula

Life cycle of a high pass star? Full order

Nebula → Protostar →Main sequence → Reg supergiant →Supernova→ Neutron Star/Black Hole

Life cycle of a Low Mass Star?

Nebula → Protostar → Main sequence → Red giant → Planetary Nebula → White dwarf → Black Dwarf