Stellar evolution for different masses, illustration. Across top is the evolution of a lower-mass star (up to 10 solar masses) via a red giant stage and a planetary nebula to form a white dwarf. Across bottom, a more massive star (a blue super giant star) explodes in a supernova, with the core collapsing to form either a neutron star or a black hole. In both cases, the star expands massively before the end of that stage of its existence. White dwarf stars, neutron stars and black holes are all extremely dense forms of matter, with very strong gravitational fields. In the case of a black hole, not even light is able to escape. Neutron stars form from stars between about 10 and 29 solar masses, with black holes forming if the collapsed core exceeds a certain mass.