J/MNRAS/509/180 GC in 5 nearby spiral galaxies (Lomeli-Nunez+, 2022)
Luminosity functions of globular clusters in five nearby spiral galaxies
using HST/ACS images.
Lomeli-Nunez L., Mayya Y.D., Rodriguez-Merino L.H., Ovando P.A.,
Rosa-Gonzalez D.
<Mon. Not. R. Astron. Soc. , 509, 180-201>
=2022MNRAS.509..180L 2022MNRAS.509..180L (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Clusters, globular ; Photometry, HST ;
Optical
Keywords: galaxies: evolution - galaxies: formation - galaxies: photometry -
galaxies: star clusters: general - galaxies: star formation
Abstract:
We here present the luminosity function (LF) of globular clusters
(GCs) in five nearby spiral galaxies using the samples of GC
candidates selected in Hubble Space Telescope mosaic images in F435W,
F555W, and F814W filters. Our search, which surpasses the fractional
area covered by all previous searches in these galaxies, has resulted
in the detection of 158 GC candidates in M81, 1123 in M101, 226 in
NGC 4258, 293 in M51, and 173 in NGC 628. The LFs constructed from
this data set, after correcting for relatively small contamination
from reddened young clusters, are lognormal in nature, which was
hitherto established only for the Milky Way (MW) and Andromeda among
spiral galaxies. The magnitude at the turn-over (TO) corresponds to
MV0(TO)=-7.41±0.14 in four of the galaxies with Hubble types Sc
or earlier, in excellent agreement with MV(TO)=-7.40±0.10 for the
MW. The TO magnitude is equivalent to a mass of ∼3x105M☉ for
an old, metal-poor population. MV0(TO) is fainter by ∼1.16 magnitude
for the fifth galaxy, M 101, which is of Hubble type Scd. The TO
dependence on Hubble type implies that the GCs in early-type spirals
are classical GCs, which have a universal TO, whereas the GC
population in late-type galaxies is dominated by old disc clusters,
which are in general less massive. The radial density distribution of
GCs in our sample galaxies follows the Sersic function with
exponential power-law indices, and effective radii of 4.0-9.5kpc. GCs
in the sample galaxies have a mean specific frequency of 1.10±0.24,
after correcting for magnitude and radial incompleteness factors.
Description:
We used the HST images of five nearby spiral galaxies for which there
are data taken with multiple pointings with ACS to enable a search of
GCs in them. Images in F435W, F555W, and F814W filters were used. We
used SExtractor and a set of cluster-defining filters to define a
sample of GCs in each of the analysed galaxies.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
galaxies.dat 37 5 Sample of spiral galaxies
table6.dat 144 1973 Observational properties of the globular clusters
in each sample galaxy
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Byte-by-byte Description of file: galaxies.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Galaxy Galaxy name
9- 11 A3 --- MType Hubble type
13- 14 I2 h RAh Right ascension (J2000)
16- 17 I2 min RAm Right ascension (J2000)
19- 22 F4.1 s RAs Right ascension (J2000)
24 A1 --- DE- Declination sign (J2000)
25- 26 I2 deg DEd Declination (J2000)
28- 29 I2 arcmin DEm Declination (J2000)
31- 32 I2 arcsec DEs Declination (J2000)
34- 37 I4 --- NGC Number of galaxy clusters
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Galaxy Galaxy name
9- 21 A13 --- Name Globular cluster name (1)
23- 32 F10.6 deg RAdeg Right ascension (J2000)
34- 42 F9.6 deg DEdeg Declination (J2000)
44- 50 F7.4 mag Imag ? F814W magnitude and error (2)
52- 57 F6.4 mag e_Imag ? F814W magnitude and error
59- 64 F6.4 mag (B-I)0 ? (F435W-F814W)0 color (3)
66- 71 F6.4 mag e_(B-I)0 ? (F435W-F814W)0 color error
73- 79 F7.4 mag (B-V)0 ? (F435W-F555W)0 color,
(F435W-F606W)0 for M81 (4)
81- 86 F6.4 mag e_(B-V)0 ? (F435W-F555W)0 color error
88- 94 F7.4 mag (U-B)0 ? (F336W-F435W)0 color,
(u-g)0 for M81 (5)
96-101 F6.4 mag e_(U-B)0 ? (F336W-F435W)0 color error
103-108 F6.4 pix FWHM FWHM from SExtractor
110-117 F8.4 pix Area ? AREA from SExtractor
119-124 F6.4 --- CI ? Concentration index (6)
126-133 F8.4 mag IMAG Absolute magnitude in F814W
135-141 F7.4 kpc Dist Galactocentric distance to the center galaxy
143-144 I2 --- Flag Flag classification (7)
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Note (1): Assigned name, which follows the convention of GAL-GCn, where GAL
stands for galaxy name and n is 1 for the brightest object in the F814W
filter, and increases sequentially as the magnitude increases.
Note (2): Magnitude in F814W-band and magnitude error from SExtractor and
aperture correction, added in quadrature
Note (3): (F435W-F814W)0 colour, the error is the quadrature sum of the error
in each band from SExtractor.
Note (4): (F435W-F555W)0 colour, the error is the quadrature sum of the error
in each band from SExtractor.
In the case of M81 the colour is (F435W-F606W)0.
Note (5): (F336W-F435W)0 colour, the error is the quadrature sum of the error
in each band. In the case of M81 the colour is. (u-g)0.
Note (6): defined as the difference between magnitudes measured in
1 and 3 pixel radius apertures
Note (7): Flag classification as follows:
00 = clusters without U-band photometry
01 = determined as a reddened young cluster from U-band photometry
02 = determined as bonafide GC from U-band photometry
03 = error in U-B is likely to be larger than the indicated formal error
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 25-Jul-2024