HESI A2 ENLISH READING LATEST 2022-2023

HESI A2 ENLISH READING LATEST 2022-2023

A binary star is actually a pair of stars that are held together by the force of gravity.

Although occasionally the individual stars that compose a binary star can be distinguished, they generally appear as one star. The gravitational pull between the individual stars of a binary star causes one to orbit around the other. From the orbital pattern of a binary, the mass of its stars can be determined: the gravitational pull of a star is in direct proportion to its mass, and the strength of the gravitational force of one star on another determines the orbital pattern of the binary.

Scientists have discovered stars that seem to orbit around an empty space. It has been suggested that such a star and the empty space really composed a binary star. The empty space is known as a "black hole," a star with such strong gravitational force that no light is able to get through. Although the existence of black holes has not been proven, the theory of their existence has been around for about two centuries, since the French mathematician Pierre Simon de Laplace first proposed the concept at the end of the eighteenth century. Scientific interest in this theory has been intense in the last few decades. However, currently the theory is unproven. Black holes can only be potentially identified based on the interactions of objects around them, as happen when a potential black hole is part of a binary star; they of course cannot be seen because of the inability of any light to escape the star's powerful gravity.

1.  A binary star could best be described as ….

C. two stars pulled together by gravity