8c-Stellar evolution

Question 1

Q: How can stars be classified according to their colour?

Answer 1

A: Stars are classified based on their temperature, which determines their colour.

Question 2

How does a star’s colour relate to its temperature?A:

Answer 2

Hotter stars appear blue or white.

Cooler stars appear red or orange.

Question 3

Star colour tempreture
Blue

Answer 3

Blue

30,000°C or more

Question 4

Star colour tempreture
White

Answer 4

White

10,000 – 30,000°C

Question 5

Star colour tempreture
Yellow

Answer 5

Yellow

5,000 – 10,000°C (e.g., the Sun)

Question 6

Star colour tempreture
Orange

Answer 6

Orange

3,500 – 5,000°C

Question 7

Star colour tempreture
Red

Answer 7

Red

Below 3,500°C

Question 8

What are the stages in the evolution of a star similar to the Sun?

Answer 8

Nebula ->Main Sequence Star -> Red Giant: ->White Dwarf:

Question 9

Nebula

Answer 9

Nebula (Cloud of Gas and Dust):

Gravity pulls gas and dust together.

Temperature increases, forming a protostar.

Question 10

Main Sequence Star:

Answer 10

Main Sequence Star:

Hydrogen nuclei undergo nuclear fusion to form helium.

Fusion releases energy, producing heat and light.

The star remains stable for millions to billions of years.

Question 11

Red Giant:

Answer 11

Red Giant:

Hydrogen fuel runs out, and the star expands.

Outer layers cool, turning the star red.

Helium fusion occurs, creating heavier elements like carbon and oxygen.

Question 12

White Dwarf:

Answer 12

White Dwarf:

The outer layers are lost, leaving behind a hot, dense core.

The star cools and fades over time.

Question 13

What happens to stars much larger than the Sun?

Answer 13

Nebula ->Red Supergiant:-> Supernova Explosion-> Neutron Star or Black Hole:

Question 14

Nebula- stars much larger than the Sun?

Answer 14

Nebula → Main Sequence Star (Same as smaller stars).

Question 15

Red Supergiant- stars much larger than the Sun?

Answer 15

Red Supergiant:

The star expands much more than a red giant.

Heavy elements (e.g., iron) form in the core.

Question 16

Supernova Explosion- stars much larger than the Sun?

Answer 16

Supernova Explosion:

The core collapses, triggering a massive explosion.

Elements heavier than iron are formed.

The explosion scatters materials into space.

Question 17

Neutron Star or Black Hole- stars much larger than the Sun?

Answer 17

Neutron Star or Black Hole:

If the core is very dense → Neutron Star (incredibly compact and massive).

If the core is extremely massive → Black Hole (gravity so strong that not even light can escape).