The death of a star results in a neutron star if the original mass of the star in terms of the mass of the Sun $(M)$ is:

There are certain types of stars called variable stars which undergo periodic changes in their light output. If such a star quadruples its light output,how much does its magnitude change?

The hottest type of stars are called

The farthest objects in our Universe discovered by modern astronomers are so distant that light emitted by them takes billions of years to reach the Earth. These objects (known as quasars) have many puzzling features,which have not yet been satisfactorily explained. What is the distance in $km$ of a quasar from which light takes $3.0$ billion years to reach us?

Which planet is known as the sister of the Earth?

What is the ratio of the maximum length to the minimum length in the universe?