Final answer:
The mass of an astronaut remains constant regardless of their location in space, whether it's between two stars or on a planet. It's the astronaut's weight that changes depending on gravity. Hence, the astronaut's mass is negligible compared to the masses of stars. Therefore the correct answer is c) The mass of the astronaut is negligible compared to the stars.
Step-by-step explanation:
When considering an astronaut positioned between two stars of equal mass, the mass of the astronaut itself does not depend on the astronaut's location compared to stars, but is an intrinsic property of the astronaut. Therefore, the correct answer is: c) The mass of the astronaut is negligible compared to the stars.
The mass of an astronaut doesn't change based on their location in space. For instance, an astronaut's mass remains constant whether they are on Earth, the Moon, or in deep space, although their weight—the force due to gravity—would change depending on the proximity to a massive body like a planet or a star.
It's important to note that in the scenario described, while the gravitational forces exerted on the astronaut by the two stars could cancel each other out, making the astronaut experience weightlessness, this does not affect the astronaut's mass at all.