The term "magnitude" doesn't refer to a specific part of a star. Instead, it describes how bright a star appears to us on Earth.

Here's a breakdown:

* Apparent Magnitude: This is the brightness of a star as seen from Earth. It's measured on a numerical scale where lower numbers indicate brighter stars. For example, a star with an apparent magnitude of 1 is brighter than a star with an apparent magnitude of 2.

* Absolute Magnitude: This is the brightness of a star if it were located at a standard distance of 10 parsecs (about 32.6 light-years) away from Earth. It's a way to compare the true intrinsic brightness of stars.

So, "magnitude" is a measure of a star's brightness, not a physical part of the star.