What is a pulsar?

A pulsar is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. These emissions occur in a regular and periodic manner, which is why pulsars are described as pulsating stars. As the star rotates, these beams can sweep across the Earth, much like a lighthouse beacon, creating the appearance of a flash of light at predictable intervals. This periodicity is what makes pulsars so distinctive and valuable in astrophysics for studying the laws of physics in extreme conditions.

The other choices do not accurately represent what a pulsar is. Some describe different types of astronomical objects, but they lack the specific characteristics that define a pulsar, such as its unique rotating and pulsating behavior paired with its emission of electromagnetic radiation in a set pattern.