The width of an emission line in this context is commonly expressed as the full width at half maximum (FWHM) and the width of an absorption line as the full width at half minimum (FWHm). (These are on...The width of an emission line in this context is commonly expressed as the full width at half maximum (FWHM) and the width of an absorption line as the full width at half minimum (FWHm). (These are on no account to be confused with the equivalent width, which is discussed in section 9.1.) Note that some writers use the term “half-width”. It is generally not possible to know what a writer means by this.
