Sérsic index
E820922
The Sérsic index is a parameter that characterizes how the intensity of light in a galaxy varies with radius, widely used to describe and classify galaxy surface brightness profiles.
Statements (49)
| Predicate | Object |
|---|---|
| instanceOf |
galaxy structural parameter
ⓘ
photometric parameter ⓘ surface brightness profile parameter ⓘ |
| appearsInEquation | I(R) = I_e * exp{-b_n[(R/R_e)^{1/n} - 1]} ⓘ |
| appliesTo | projected (2D) light distribution of galaxies ⓘ |
| characterizes |
radial variation of galaxy light intensity
ⓘ
shape of galaxy surface brightness profile ⓘ |
| commonlyUsedFor |
bulge–disk decompositions
ⓘ
disk galaxies ⓘ elliptical galaxies ⓘ |
| correlatesWith |
bulge-to-total light ratio
ⓘ
central surface brightness ⓘ effective radius ⓘ galaxy stellar mass ⓘ |
| dependsOn |
choice of photometric band
ⓘ
radial fitting range ⓘ sky background estimation ⓘ |
| describes | concentration of light in a galaxy ⓘ |
| domain | galaxy surface brightness profiles ⓘ |
| fittedUsing |
maximum likelihood methods
ⓘ
nonlinear least-squares methods ⓘ |
| hasCommonValues |
n = 1
GENERATED
ⓘ
n = 4 GENERATED ⓘ |
| hasTypicalRange | 0.2–10 ⓘ |
| higherValueIndicates | more centrally concentrated light profile ⓘ |
| implementedIn |
GALFIT
NERFINISHED
ⓘ
GIM2D NERFINISHED ⓘ IMFIT NERFINISHED ⓘ |
| introducedBy | José Luis Sérsic NERFINISHED ⓘ |
| introducedIn | 1963 ⓘ |
| lowerValueIndicates | less centrally concentrated light profile ⓘ |
| measuredFrom |
azimuthally averaged surface brightness profiles
ⓘ
two-dimensional galaxy images ⓘ |
| namedAfter | José Luis Sérsic NERFINISHED ⓘ |
| nEquals |
1 for exponential profile
ⓘ
4 for de Vaucouleurs profile ⓘ |
| parameterOf | I(R) = I_e * exp{-b_n[(R/R_e)^{1/n} - 1]} ⓘ |
| partOf | Sérsic profile NERFINISHED ⓘ |
| relatedTo | galaxy morphological type ⓘ |
| symbol | n ⓘ |
| usedAsProxyFor |
bulge prominence
ⓘ
galaxy concentration index ⓘ |
| usedIn |
extragalactic astronomy
ⓘ
galaxy morphology studies ⓘ galaxy structural decomposition ⓘ surface photometry ⓘ |
| usedToClassify |
early-type galaxies
ⓘ
late-type galaxies ⓘ |
| usedToDistinguish | disk-dominated galaxies from bulge-dominated galaxies ⓘ |
Referenced by (1)
Full triples — surface form annotated when it differs from this entity's canonical label.