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Compilation of morphology of galaxies |
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This catalogue (table a102 in the database) presents the compilation of the
morphology of galaxies. It contains the morphological type encoded
in the de Vaucouleurs scale as well as information on the presence
of a bar or ring, the luminosity class (van den Bergh's definition),
the compacity and the multiplicity.
The morphological information derived
from the combination of the various estimates for a given galaxy
is presented in the homogenized catalogue
(fields t and
type).
The morphological type is used for computing several
other astrophysical parameters, in particular for estimating geometric
and photometric corrections which depends on the SED and intrinsic
shape.
For more details about the
classification of galaxies read the
article
Qualitative classification of galaxies, alternate systems and
modifications
from the NED knowledge
database (Level 5).
Beside references providing a detailed classifications, the compilation includes
approximates descriptions (typically differentiating elliptical and spiral
galaxies; E/S). These descriptions are given the 'quality' code 3.
Indirect estimates of the type are also compiled, like those derived
from the shape of the photometric profiles (quality=2; for 2MASS, ref=27129,
the type was computed from the concentration index as: t=10-2*concent). (To compute the homogenized classification, these crude
estimates are naturally used only if no detailed description is available).
The reference system of the morphological classification is the RC3
(reference code=4008) which provide 18883 morphological descriptions.
The main references are listed below:
Below is a description of the fields of
the table that can be accessed
through the interfaces.
Field: Type
Extended RC3 Morphological type (de Vaucouleur's scale)
Field: bar
Bar
0 |
no bar is mentioned
|
1 |
intermediate bar |
2 |
bar |
Ring
0 |
no ring is mentioned
|
1 |
ring |
Field: lum_cl
Luminocity
Class
Field: bri
Brightness
1 |
compact galaxy |
2 |
very compact galaxy |
3 |
extremely compact galaxy |
4 |
diffuse galaxy |
5 |
very diffuse galaxy |
6 |
extremely diffuse galaxy |
Field: inter
1 |
Interaction mentioned |
2 |
Strong interaction in the center of a cluster (cD galaxy) |
Field: mult
Multiplicity
1 |
multiplicity mentioned |
2 |
double |
3 |
triple |
4 |
quadruple |
5 |
multiple |
9 |
superimposed star mentioned |
Field: quality
Quality Flag
0 |
accurate detailed classification |
1 |
detailed classification of lower accuracy
|
2 |
derived from photometric profile
|
3 |
large uncertainty
|
9 |
measurement to be rejected |