J/AJ/168/264 Morphology of spiral galaxies from Galaxy Zoo & SDSS (Wei+, 2024)
A new statistical analysis of the morphology of spiral galaxies.
Wei J., Xu Ye, Lin Z., Hao C., Li Y., Liu D., Bian S.
<Astron. J., 168, 264 (2024)>
=2024AJ....168..264W 2024AJ....168..264W
ADC_Keywords: Galaxies; Optical; Redshifts
Keywords: Galaxy structure ; Spiral arms ; Milky Way Galaxy ; Spiral galaxies
Abstract:
Morphology is the starting point for understanding galaxies. Elmegreen
et al. classified spiral galaxies into flocculent, multiple-arm, and
grand-design galaxies based on the regularity of their spiral arm
structure. With the release of a vast number of clear spiral galaxy
images from the Sloan Digital Sky Survey, we conducted a morphological
classification of 5093 blue spiral galaxies. A statistical analysis of
this sample shows that the fractions of flocculent, multiple-arm, and
grand-design galaxies are 38%±1%, 59%±1%, and 3%±1%,
respectively. Redshift has no obvious influence on this
classification. However, as the bulge size becomes larger, the
fraction of multiple-arm galaxies increases, while that of flocculent
galaxies decreases. In addition, we performed a statistical analysis
of 3958 galaxies with a clear spiral arm structure, finding that 82%
of these galaxies have two arms in their inner regions. We also found
that the majority (74%) of the barred spiral galaxies exhibit the
characteristics of two inner spiral arms and multiple outer spiral
arms, and there is no barred spiral galaxy in this work with four
continuous spiral arms from the inner to the outer regions. These
results highlight that the spiral arm structure of the Milky Way,
according to the current mainstream view of a four-arm galaxy with
continuous arms extending from the inner to outer regions, is quite
unique. However, our findings align with the spiral morphology of the
Milky Way proposed by Xu et al., in which case our Galaxy can be
considered typical.
Description:
The Galaxy Zoo project provides a large sample of spiral galaxies. The
sample used in this study originates from the work of
Masters+2010 (J/MNRAS/405/783), who selected 5139 blue spiral galaxies
from the SDSS Main Galaxy Sample (Strauss+, 2002AJ....124.1810S 2002AJ....124.1810S) by
controlling the parameters based on SDSS Data Release 6
(Adelman-McCarthy+2008, II/282). We have updated this sample by using
the latest data release from SDSS, i.e., DR18, and obtained a sample
containing 5093 blue spiral galaxies. Note that since the sample
consists of blue spiral galaxies, this sample cannot be representative
of all disk galaxies.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 57 5093 Morphology and structure of the spiral galaxies in
this study
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See also:
II/282 : The SDSS Photometric Catalog, Release 6 (Adelman-McCarthy+, 2007)
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)
VIII/39 : Composite CO Survey of the Milky Way (Dame+ 1987)
J/MNRAS/278/1025 : The APM Bright Galaxy Catalogue (Loveday 1996)
J/A+A/397/133 : Star-forming complexes in the Galaxy (Russeil+, 2003)
J/MNRAS/405/783 : Passive red spirals in Galaxy Zoo (Masters+, 2010)
J/MNRAS/410/166 : Morphological types from Galaxy Zoo 1 (Lintott+, 2011)
J/MNRAS/435/2835 : Morphological types from Galaxy Zoo 2 (Willett+, 2013)
J/A+A/569/A125 : Spiral structure of the Milky Way (Hou+, 2014)
J/ApJS/217/32 : S4G galaxy morphologies in the CVRHS system (Buta+, 2015)
J/ApJ/885/131 : ∼200 high-mass SFR plx & proper motion with VLBI (Reid+, 2019)
J/ApJ/947/54 : High-mass SFR masers w/ VLBI & external MW-like gal. (Xu+, 2023)
http://www.sdss.org/dr18/ : SDSS DR18
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- SDSS SDSS identifier (JHHMMSS.ss+DDMMSS.s)
21 A1 --- Morph1 First classification of the spiral galaxy
morphology (1)
23 A1 --- Morph2 Second classification of the spiral galaxy
morphology (1)
25- 30 F6.4 --- z [0.03/0.09] Redshift of the galaxy
32- 35 F4.2 --- fDeV [0.0/0.5] SDSS structural parameter (5)
37 A1 --- Bar Whether the galactic center has a bar; Yes or
No
39 I1 --- InnerArm [1/4]? Number of inner arms (2)
41- 44 F4.2 --- (Rb/R)1 [0.0/0.8]? First statistic of relative
position of branching points (3)
46- 49 F4.2 --- (Rb/R)2 [0.0/0.86]? Second statistic of relative
position of branching points (3)
51- 53 I3 deg Theta1 [0/301]? Angle of one of the inner arm's
branching point (4)
55- 57 I3 deg Theta2 [80/359]? Angle of the other inner arm's
branching point (4)
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Note (1): Morphologies as follows:
F = flocculent; exhibits fragmented and chaotic arms, with poor symmetry
and continuity (2003 occurrences for Morph1, 1901 for Morph2)
M = multiple-arm; features arms with some symmetry and continuity, often
showcasing two symmetric arms in the inner or outer parts
(2990 occurrences for Morph1, 3027 for Morph2)
G = grand-design; possesses two long, strongly continuous, and symmetric
arms (100 occurrences for Morph1, 165 for Morph2)
Note (2): A blank field indicated an uncertain inner arm count.
Note (3): The radius of the galaxy's arm branching points, Rb, divided by
the galaxy radius, R. This parameter takes into account only the
branching points closest to the center of the galaxy. A value of 0
indicates that the galaxy has arms without branches or with
indistinct branching. A blank field indicates that the arm(s) cannot
be counted because they are ambiguous or the arm(s) gradually spread
out during their extension, making it impossible to determine the
branching point location.
Note (4): The angles are measured counterclockwise from the western axis.
Note (5): Indicates the size of a galactic bulge. Spiral galaxies with larger
values of fDeV usually have larger bulges.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Robin Leichtnam [CDS] 01-Sep-2025