Glosario - F

Faculae (plural of facula) are bright spots on a star's photosphere formed by concentrations of magnetic field lines. For the Sun, they are most readily observed near the solar limb. An increase in faculae as a result of a stellar cycle increases the star's total irradiance.

A field galaxy is a galaxy that does not belong to a larger cluster of galaxies, but is gravitationally alone.

A field star is a randomly situated star that lies along the line of sight to a group of physically associated stars under study, such as a star cluster. These field stars can contaminate the results for a study and so they need to be identified.[7]

Flare star is a class of variable stars that undergo sudden, dramatic increases in brightness due to magnetic activity on its surface. This change on brightness occurs across the electromagnetic spectrum from radio waves to X-rays. Most flare stars are faint red dwarfs.