The search for black holes involves searching for Group of answer choices single stars that emit large amounts of X-rays. a stellar core greater than 3 solar masses large spherical regions from which no light is detected. pulsars with periods less than one millisecond. pulsars that are orbited by planets.

A stellar core greater than 3 solar masses

Explanation:

The process of the evolution of a star in which the star changes form with time, includes phases of evolution which are determined by the mass of the core of the star, which involves a process of conversion of elements and the contraction of the star

Where the mass of the core of the star is more than the mass of three Suns, (3 solar masses) the contraction of the star continues, due to the gravitational force being larger than the pressure exerted by neutron, such that the star collapses to a black hole

Therefore, the search for black holes involves searching for a stellar core greater than 3 solar masses.

unlike poles attract