air
The hard center part of a feather is called the quill or shaft. It provides support and structure to the feather and attaches it to the bird's skin.
The center of a flame is called the "inner cone." It is the hottest part of the flame and appears blue in color due to the complete combustion of the fuel.
in the center. Its called a Nucleus. It controlls the atom
The center portion of a sunspot is called the umbra. It is the darkest part of the sunspot where the magnetic field is strongest and the temperature is cooler than the surrounding areas.
The showy part of a daisy flower is the white or colored petals that surround the yellow center, known as the disk floret. These petals are often the most visually striking and are what distinguish daisies from other flowers in the Asteraceae family.
The center
I believe, although I may be incorrect, that the center, or core for that matter, is still a part of the pith, the white stuff on the peel.
the center part of the tree is called the core.
the edge
Well, sweetheart, the yellow part is called the yolk, and the white part is called the egg white. It's as simple as that. No need to complicate things, darling.
The white part of an egg is called the (Egg white). It's also called albumen.
The white of the eye is called the Sclera.
It is called the hub.
the red and white part
puke
The center of the nut or the edible part is generally called the "nut meat" or the kernel.
The white part of the bread is known as the "crumb."