Question

Which of the following is most similar to a white dwarf?

A) The core of a red giant. B) A pulsar. C) A neutron star. D) The core of a blue supergiant.

Considering the conditions for equilibrium in stars, which star does not belong in the following list?

- Blue Main Sequence star - Red Main Sequence star - Red Giant star - White Dwarf - Horizontal Branch star

A) The Red Main Sequence star, because energy losses at its surface are not balanced by energy production inside the star.

B) The Blue Main Sequence star, because gas pressure does not balance gravity everywhere inside the star.

C) The Horizontal Branch star, because energy losses at its surface are not balanced by energy production inside the star

D) The Red Giant star, because gas pressure does not balance gravity everywhere inside the star.

E) The White Dwarf star, because energy losses at its surface are not compensated by energy production inside the star.

What can we observe about the surface of a massive star approximately a week before it explodes as a supernova?

A) The surface suddenly becomes larger. B) The surface suddenly becomes hotter. C) The surface suddenly becomes cooler. D) There is nothing out of the ordinary that we can observe on the surface. E) The spectrum shows very strong spectral lines of iron.

Answer 1

=> A neutron star is most similar to the white dwarf. Both of them are the last stages of star life cycle

Hence option C is correct

=> White dwarf is the last stage of star lifecycle. It is also know as dead star. Except this all other option are the example of balanced equilibrium inside star. White dwarf itself results from the unbalanced conditions which occurs when a main sequence star convert to red Giant.

Hence option E is correct

=> The surface suddenly becomes cooler and crab nebula can be observed

Hence option C is correct