Marvel: Solar Radiation Absorption

Leyu Yoshida (Sunpyre)
Sunpyre's mutant powers enable her to absorb solar and other radiation to generate the process of ionized matter through a mentally-triggered unknown biochemical process so that it is converted to plasma, the superheated state of matter. Plasma is the state in which matter making up the sun exists; hence, Sunpyre refers to her projecting "solar fire". Hence, she can sheath her body in flame.

Roberto da Costa (Sunspot)
Sunspot absorbs solar energy and can utilize it for physical strength. The cells of a normal human body convert energy from foodstuffs into a form of energy usable by the body. This energy is stored through converting molecules of adenosine diphosphate (ADP) in the cells into adenosine triphosphate (ATP); the energy is released when necessary by breaking a chemical bond in the ATP molecules, converting them back to ADP. Apparently, Sunspot can store solar-derived energy in his cells through the same, or a similar, method and release it when necessary to enhance his physical strength. His body is cloaked in darkness because he drains all the ambient light from his skin.

Shiro Yoshida (Sunfire)
Sunfire's mutant powers enable him to absorb solar and other radiation to generate the process of ionized matter through a mentally-triggered unknown biochemical process so that it is converted to plasma, the superheated state of matter. Plasma is the state in which matter making up the sun exists; hence, Sunfire refers to his power as projecting "solar fire".