The HR diagram represents stages in the life cycle of a star.

Which type of star is A and C?

black hole

blue giant

white dwarf

red giant

white dwarf

Explanation:

A appears on the chart at the point of low luminosity but high surface temperatures. This indicated  a White Dwarf

A red giant is highly luminous stars mainly because of its large size. However, its surface temperature is hot a high when compared to white dwarfs. White dwarf surface temperatures can reach billions of degrees kelvin while red giants reach up to 5000 K on their surface.

A white dwarf is the last sequence of a low-mass star cycle and follows the red giant phase.

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