J/AJ/121/148 Photometry of Dorado Group Dwarf Galaxies (Carrasco+, 2001)
The dwarf galaxy population of the Dorado group down to Mv ≃ -11.
Carrasco E.R., De Oliveira C.M., Infante L., Bolte M.
<Astron. J., 121, 148-168 (2001)>
=2001AJ....121..148C 2001AJ....121..148C
ADC_Keywords: Photometry, CCD ; Photometry, surface ; Clusters, galaxy
Keywords: Galaxies: Clusters: General, Galaxies: Clusters: Individual: Name:
Dorado Group, Galaxies: Dwarf, Galaxies: Fundamental Parameters,
galaxies: luminosity function
Abstract:
We present V and I CCD photometry of suspected low surface brightness
dwarf galaxies detected in a survey covering ∼2.4 deg2 around the
central region of the Dorado group of galaxies. The low surface
brightness galaxies were chosen based on their sizes and magnitudes at
the limiting isophote of 26Vµ. The selected galaxies have
magnitudes brighter than V∼20 (MV~-11 for an assumed distance to the
group of 17.2 Mpc), with central surface brightnesses µ0>22.5
Vmag.arcsec-2, scale lengths h>2", and diameters ≥14" at the
limiting isophote. Using these criteria, we identified 69 dwarf galaxy
candidates. Four of them are large very low surface brightness
galaxies that were detected on a smoothed image, after masking high
surface brightness objects. Monte Carlo simulations performed to
estimate completeness, photometric uncertainties and to evaluate our
ability to detect extended low surface brightness galaxies show that
the completeness fraction is, on average, >80% for dwarf galaxies
with -17<MV←10.5 and 22.5<µ0<25.5 Vmag.arcsec-2, for the
range of sizes considered by us (D≥14"). The V-I colors of the dwarf
candidates vary from -0.3 to 2.3 with a peak on V-I=0.98, suggesting
a range of different stellar populations in these galaxies. The
projected surface density of the dwarf galaxies shows a concentration
toward the group center similar in extent to that found around five
X-ray groups and the elliptical galaxy NGC 1132 studied by Mulchaey &
Zabludoff (1999ApJ...514..133M 1999ApJ...514..133M), suggesting that the dwarf galaxies in
Dorado are probably physically associated with the overall potential
well of the group.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 84 69 Photometric Data and Profile Fit Parameters
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- ID Dwarf galaxy identification
11 A1 --- f_ID [f] Indicates not detected in I filter
(see section 2.7)
13 I1 h RAh Right ascension (J2000)
15- 16 I2 min RAm Right ascension (J2000)
18- 21 F4.1 s RAs Right ascension (J2000)
23 A1 --- DE- Sign of the declination (J2000)
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 31 I2 arcsec DEs Declination (J2000)
33- 37 F5.2 mag Vmag Total V-band magnitude (1)
39- 43 F5.2 mag V-I ? The V-I color (1)
45- 48 F4.1 arcsec D26 Limiting isophotal diameter at
26 V mag/arcsec2
50 A1 --- f_D26 [e] Flag on D26 (2)
52- 55 F4.1 arcsec Theta26 Eq. (4) diameter at 26 V mag/arcsec2
57 A1 --- f_Theta26 [e] Flag on Theta26 (2)
59- 62 F4.1 mag/arcsec2 Mu0 Extrapolated central surface brightness
in V
64- 67 F4.1 arcsec Scl Scale length
69- 72 F4.1 arcsec Rad Effective radius
74- 77 F4.1 mag/arcsec2 Mueff Mean effective surface brightness
79- 82 A4 --- Type Morphological type (see section 3.1)
84 A1 --- f_Type Flag on Type (3)
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Note (1): Magnitude within 7'' and 4'' diameter apertures for CTIO and
LCO40 data, respectively. Not corrected according to the simulation
in section 2.6 and not corrected by interstellar absorption.
Note (2): Limiting isophotal diameter and diameter given by equation (4)
at the surface brightness of 26.5 V mag/arcsec2.
Note (3): the flag takes the folloxing values:
b = Shows knots of star formation regions;
c = Red irregular galaxy;
d = Extended irregular low surface brightness cloud located ∼10' to
the northwest of the NGC 1549 galaxy.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Laurent Cambresy [CDS] 23-Jul-2004