Some binary objects emit X-rays because material flows away from one object in the pair and forms a whirlpool spiraling down onto the other object. As this material flows away from the star and swirls down to the other object, it heats up to extremely high temperatures and emits X-rays. This article describes observations of high-mass X-ray binaries and studies how the brightness of the X-rays varies over time, giving astronomers more insights into these types of objects.