J/MNRAS/493/390 Study of spiral structure in galaxies (Savchenko+, 2020)
A multiwavelength study of spiral structure in galaxies.
I. General characteristics in the optical.
Savchenko S., Marchuk A., Mosenkov A., Grishunin K.
<Mon. Not. R. Astron. Soc., 493, 390-409 (2020)>
=2020MNRAS.493..390S 2020MNRAS.493..390S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, photometry ; Galaxy catalogs ; Optical
Keywords: methods: data analysis - galaxies: spiral - galaxies: structure
Abstract:
Different spiral generation mechanisms are expected to produce
different morphological and kinematic features. In this first paper in
a series, we carefully study the parameters of spiral structure in 155
face-on spiral galaxies, selected from the Sloan Digital Sky Survey,
in the three gri bands. We use a method for deriving a set of
parameters of spiral structure, such as the width of the spiral arms,
their fraction to the total galaxy luminosity, and their colour, which
have not been properly studied before. Our method is based on an
analysis of a set of photometric cuts perpendicular to the direction
of a spiral arm. Based on the results of our study, we compare the
main three classes of spirals: grand design, multi-armed, and
flocculent. We conclude that: (i) for the vast majority of galaxies
(86 per cent), we observe an increase of their arm width with
Galactocentric distance; (ii) more luminous spirals in grand design
galaxies exhibit smaller variations of the pitch angle with radius
than those in less luminous grand design spirals; (iii) grand design
galaxies show less difference between the pitch angles of individual
arms than multi-armed galaxies. Apart from these distinctive features,
all three spiral classes do not differ significantly by their pitch
angle, arm width, width asymmetry, and environment. Wavelength
dependence is found only for the arm fraction. Therefore,
observationally we find no strong difference (except for the view and
number of arms) between grand design, multi-armed, and flocculent
spirals in the sample galaxies.
Description:
In this paper, we used SDSS gri-band images to perform a detailed
analysis of the spiral structure in the 155 face-on non-interacting
spiral galaxies. Our sample is mostly composed of multi-armed and
grand design galaxies, with a fraction of flocculent galaxies, in
which at least one arm could be visually traced.
In our study, we used an approach of fitting an arm profile by
creating a series of photometric cuts perpendicular to its direction.
For tracing the spiral structure, we start from the inner galaxy
region to the outermost regions to which we are able to trace the
spirals. Along with the pitch angle and its variation with radius, we
measured, for the first time based on the spiral view in the optical,
the arm width and its variation with Galactocentric distance, the
fraction of the spiral structure to the total galaxy luminosity, and
its colour. Coupling with the arm number and the general arm class
(grand design, flocculent, or multi-armed), these quantities define
the photometric properties of the spiral structure in galaxies, which
can in principle be used to distinguish between different mechanisms
of generating spiral structure in galaxies.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 67 155 General characteristics of the sample galaxies
table2.dat 55 155 Results of the fitting for the r band
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See also:
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Galaxy name (PCGNNNNNNN)
12- 16 F5.1 Mpc Dist Distance calculated from the best distance
modulus from HyperLeda
18- 22 F5.3 kpc/arcsec Scale Scale calculated from the best distance
modulus from HyperLeda
24- 27 F4.2 arcmin r25 Semimajor axis of the isophote 25mag/arcsec2
in the r band
29- 32 F4.2 --- q25 Median flattening between the
24-25mag/arcsec2 isophotes in the r band
34- 38 F5.2 mag rmag Apparent asymptotic magnitude in the
r-band (1)
40- 45 F6.2 mag rMAG Absolute magnitude in the r-band (1)
47- 50 F4.2 mag g-r g-r colour index (2)
52- 56 F5.2 mag r-i r-i colour index (2)
58- 61 F4.1 --- Type Numerical morphological type from HyperLeda
63- 65 A3 --- Env Environment (3)
67 A1 --- Bar [+ ] Bar presence according to the visual
inspection
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Note (1): Apparent asymptotic and absolute magnitudes in the r band calculated
from the growth curve, corrected for the Milky Way extinction
(Schlafly & Finkbeiner 2011ApJ...737..103S 2011ApJ...737..103S)
Note (2): Colours calculated from the corresponding asymptotic magnitudes and
corrected for the Milky Way extinction (Schlafly & Finkbeiner
2011ApJ...737..103S 2011ApJ...737..103S)
Note (3): Environment as follows:
G = belongs to a group (information from NED)
g = belongs to a group (information from Tempel et al. 2012A&A...540A.106T 2012A&A...540A.106T,
Cat. J/A+A/540/A106)
P = belongs to a pair (information from NED)
p = belongs to a pair (information from Tempel et al. 2012A&A...540A.106T 2012A&A...540A.106T,
Cat. J/A+A/540/A106)
T = belongs to a triple (information from NED)
t = belongs to a triple (information from Tempel et al. 2012A&A...540A.106T 2012A&A...540A.106T,
Cat. J/A+A/540/A106)
I = isolated galaxy (information from NED)
i = isolated galaxy (information from Tempel et al. 2012A&A...540A.106T 2012A&A...540A.106T,
Cat. J/A+A/540/A106)
C = belongs to a cluster (information from NED)
C = belongs to a cluster (information from Tempel et al. 2012A&A...540A.106T 2012A&A...540A.106T,
Cat. J/A+A/540/A106)
? = means that classification is found neither in NED nor in Tempel et al.
(2012A&A...540A.106T 2012A&A...540A.106T, Cat. J/A+A/540/A106) and we classified the galaxy
environment on our own using the SDSS SkyServer Navigate tool on the basis
of visual closeness to the target galaxy and known spectroscopic redshift
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Galaxy name (PCGNNNNNNN)
12- 15 F4.1 deg <Psi> Mean pitch angle averaged for all spiral arms
we traced (1)
17- 19 F3.1 --- Psirel ? Relative pitch angle variation along the
radius
21- 24 F4.2 --- w ? Mean width of spiral arms (in units of
r25) averaged for all spiral arms we traced
26- 32 F7.4 --- a ? Slope of the best linear fit to the radial
width variation (2)
34- 38 F5.2 --- Asym ? Mean asymmetry of the cuts (3)
40- 43 F4.2 --- farms ? Fraction of the spiral pattern in the total
galaxy flux in the r band
45- 48 F4.2 mag g-r g-r colour of the spiral pattern
50 A1 --- Typearms [GMF] Arm class (4)
52- 53 A2 --- l_Narms [≥ ] Limit flag on Narms
55 I1 --- Narms Number of arms
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Note (1): The pitch angle Ψ is defined as the angle between the tangent of
the spiral and azimuthal directions
Note (2): Positive values mean that the width increases with radius
Note (3): Positive values mean that the inner slope of the cuts is steeper
Note (4): Arm class as follows:
G = Grand design (34/155)
M = Multi-armed (101/155)
F = Flocculent (20/155)
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 30-Mar-2023