What method is used by astronomers to infer the existence in space of a dark object with a mass of about 5 solar masses such as a black hole?
A) The measurement of the effect of its gravitational force on a companion object in a binary system
B) The measurement of the gravitational redshift of spectral lines in the spectrum of the object
C) The estimation of the luminosity of the object and the application of the mass-luminosity relationship
D) The photography or imaging of a region from which no light or radiation at all appears to come

Question

Quizplus · Accepted Answer

Astronomers can infer the existence of a dark object with a mass of about 5 solar masses such as a black hole by measuring the effect of its gravitational force on a companion object in a binary system. By observing the motion of the companion object, astronomers can calculate the mass of the unseen object and determine if it is consistent with the mass of a black hole.

What Method Is Used by Astronomers to Infer the Existence