J/AJ/144/134 LITTLE THINGS survey of nearby dwarf galaxies (Hunter+, 2012)
LITTLE THINGS.
Hunter D.A., Ficut-Vicas D., Ashley T., Brinks E., Cigan P.,
Elmegreen B.G., Heesen V., Herrmann K.A., Johnson M., Oh S.-H., Rupen M.P.,
Schruba A., Simpson C.E., Walter F., Westpfahl D.J., Young L.M.,
Zhang H.-X.
<Astron. J., 144, 134 (2012)>
=2012AJ....144..134H 2012AJ....144..134H
ADC_Keywords: H I data ; Galaxies, nearby ; Reddening ; Abundances
Keywords: galaxies: irregular - galaxies: ISM - galaxies: star formation -
galaxies: kinematics and dynamics - galaxies: structure
Abstract:
We present LITTLE THINGS (Local Irregulars That Trace Luminosity
Extremes, The HI Nearby Galaxy Survey), which is aimed at determining
what drives star formation in dwarf galaxies. This is a
multi-wavelength survey of 37 dwarf irregular and 4 blue compact dwarf
galaxies that is centered around HI-line data obtained with the
National Radio Astronomy Observatory (NRAO) Very Large Array (VLA).
The HI-line data are characterized by high sensitivity
(≤1.1mJy/beam per channel), high spectral resolution (≤2.6km/s),
and high angular resolution (∼6"). The LITTLE THINGS sample contains
dwarf galaxies that are relatively nearby (≤10.3Mpc; 6" is
≤300pc), that were known to contain atomic hydrogen, the fuel for
star formation, and that cover a large range in dwarf galactic
properties. We describe our VLA data acquisition, calibration, and
mapping procedures, as well as HI map characteristics, and show
channel maps, moment maps, velocity-flux profiles, and surface gas
density profiles. In addition to the HI data we have GALEX UV and
ground-based UBV and Hα images for most of the galaxies, and JHK
images for some. Spitzer mid-IR images are available for many of the
galaxies as well. These data sets are available online.
Description:
The LITTLE THINGS ((Local Irregulars That Trace Luminosity Extremes,
The HI Nearby Galaxy Survey) sample of 37 dwarf Irregular (dIrr)
galaxies and 4 blue compact dwarf (BCDs) galaxies was drawn from a
larger multi-wavelength survey of 94 relatively nearby dIrr galaxies
and 24 BCD systems, as well as 18 Magellanic spiral (Sm) galaxies
(Hunter & Elmegreen, 2004, cat. J/AJ/128/2170; Hunter & Elmegreen,
2006, J/ApJS/162/49). LITTLE THINGS is a multi-wavelength survey that
is centered around HI-line data obtained with the National Radio
Astronomy Observatory (NRAO) Very Large Array (VLA). Our new VLA
observations are characterized by deep observations with high angular
and high spectral resolution. To achieve the angular resolution and
sensitivity we needed, we used VLA B/C/D-array configurations. The
LITTLE THINGS (project AH927) observations began with the B array 2007
December 19 and, for B array, ended 2008 February 10. C-array
observations followed in the spring of 2008 and D-array observations
in the summer of 2008.
In our sample of galaxies requiring new VLA observations, 13 had no
previous VLA observations and 8 had some data in the archives.
Altogether, there were 21 galaxies that needed B array observations,
15 that needed C, and 17 needed D configurations. Seven of our
galaxies (CVnIdwA, DDO 70, DDO 75, DDO 155, DDO 187, NGC 4163, and UGC
8508) are part of the VLA-ANGST (ACS (Advanced Camera for Surveys)
Nearby Galaxy Survey Treasury) large project (Ott et al.,
2010AAS...21520203O 2010AAS...21520203O; project ID AO215) that began at the same time as
LITTLE THINGS. These galaxies were observed as part of VLA-ANGST
rather than LITTLE THINGS and we use those data here. In addition
eight of our galaxies (DDO 50, DDO 53, DDO 63, DDO 154, M81dwA, NGC
1569, NGC 2366, and NGC 4214) taken entirely from the archives were
part of the THINGS (Walter et al., 2008, Cat. J/AJ/136/2563) sample.
There are two galaxies (DDO 216 and SagDIG) that are exceptions to our
combination of the B/C/D-array configurations. The data for these
galaxies were taken from the archives where only C- and D-array
configuration data were available.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 158 41 The galaxy sample
table4.dat 31 41 Integrated masses
table6.dat 50 41 *Surface Density Photometry Parameters
refs.dat 67 42 References
--------------------------------------------------------------------------------
Note on table6.dat: From the V band (Hunter & Elmegreen, 2006, J/ApJS/162/49).
--------------------------------------------------------------------------------
See also:
VIII/77 : HI spectral properties of galaxies (Springob+, 2005)
J/AJ/142/145 : Outer disks of S0-Sb gal. II. Surface-brightness
(Gutierrez+, 2011)
J/AJ/140/1194 : FUV/HI relations in nearby galaxies (Bigiel+, 2010)
J/ApJS/190/233 : Spectroscopy & abundances of SINGS galaxies (Moustakas+, 2010)
J/ApJ/703/517 : The Spitzer Local Volume Legacy: IR photometry (Dale+, 2009)
J/AJ/136/2563 : HI Nearby Galaxy Survey, THINGS (Walter+, 2008)
J/AJ/133/2569 : Arecibo legacy fast ALFA survey III. (Giovanelli+, 2007)
J/ApJS/164/81 : Spectrophotometry of nearby galaxies (Moustakas+, 2006)
J/ApJS/162/49 : UBV imaging of irregular galaxies (Hunter+, 2006)
J/ApJ/647/1056 : ARAUCARIA project : NGC 6822 Cepheid variables (Gieren+, 2006)
J/ApJ/636/214 : HII regions in dwarf irregular galaxies (van Zee+, 2006)
J/AJ/128/2170 : Hα imaging of irregular galaxies (Hunter+, 2004)
J/AJ/127/2031 : Catalog of neighboring galaxies (Karachentsev+, 2004)
J/AJ/128/16 : HIPASS Bright Galaxy Catalog (Koribalski+, 2004)
J/A+A/398/479 : Local galaxy flows within 5 Mpc (Karachentsev+, 2003)
J/AJ/125/1261 : VI photometry of Sextans A Cepheids (Dolphin+, 2003)
J/AJ/123/3154 : RV light curves of variable stars in Leo A (Dolphin+, 2002)
J/ApJS/131/47 : Gas-rich dwarfs from the POSS-II. III. (Eder+, 2000)
J/AJ/116/146 : UGC 6456 HST photometry (Lynds+ 1998)
http://www.lowell.edu/users/dah/littlethings/index.html : LITTLE THINGS
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Cl Galaxy class: Im=dwarf irregular,
BCD=Blue Compact Dwarf
5- 13 A9 --- Name Galaxy name
15 A1 --- f_Name [a] The data for the galaxy NGC 6822
require special treatment (see
section 2.1). So NGC 6822 is not
included in tables 4 and 6.
17- 19 A3 --- --- [PGC]
21- 25 I5 --- PGC ? Galaxy PGC identifier (from NED)
27- 29 A3 --- --- [UGC]
31- 35 I5 --- UGC ? Galaxy UGC identifier (from NED)
37- 50 A14 --- OName1 Other name (from NED) (1)
52- 64 A13 --- OName2 Other name (from NED)
66- 85 A20 --- OName3 Other name (from NED)
87- 90 F4.1 Mpc Dist Galaxy distance
92- 96 A5 --- r_Dist Reference for the distance to the
galaxy (2)
98-102 F5.1 mag VMag Galaxy absolute magnitude
104-107 F4.2 arcmin Rad ? Holmberg radius RH (3)
109-112 F4.2 kpc Rd The disk scale length (4)
114-117 F4.2 kpc e_Rd Uncertainty in Rd
119-122 F4.2 mag E(B-V) Foreground reddening from Burstein &
Heiles (1984ApJS...54...33B 1984ApJS...54...33B)
124-128 F5.2 [Msun/yr/kpc2] logSFR1 ? Star formation rate from Hα
(log SFRHαD) (5)
130-133 F4.2 [Msun/yr/kpc2] e_logSFR1 ? Uncertainty in logSFR1
135-139 F5.2 [Msun/yr/kpc2] logSFR2 ? Star formation rate from UV
(log SFRFUVD) (6)
141-144 F4.2 [Msun/yr/kpc2] e_logSFR2 ? Uncertainty in logSFR2
146 A1 --- f_[O/H] [*] Empirical estimation of [O/H] (7)
148-150 F3.1 [-] [O/H] Oxygen abundance 12+log(O/H) (measure
of the metallicity of the galaxy) (8)
152-155 F4.2 [-] e_[O/H] ? Uncertainty in [O/H]
157-158 I2 --- r_[O/H] Reference for [O/H]
--------------------------------------------------------------------------------
Note (1): IIZw 499 is a misprint for VII Zw 499; corrected at CDS.
Note (2): Distance determinations given by the NASA/IPAC Extragalactic
Database (NED). In order of preference, we choose distances
determined from Cepheids or RR Lyrae stars and from the tip of the red
giant branch. If no reference is given, the distance was determined
from the galaxy's radial velocity, given by de Vaucouleurs et al.
(1991rc3..book.....D 1991rc3..book.....D), corrected for infall to the Virgo Cluster
(Mould et al., 2000ApJ...529..786M 2000ApJ...529..786M) and a Hubble constant of
73km/s/Mpc.
Note (3): The radius of galaxy at a B-band isophote, corrected for reddening, of
26.7mag of of 1arcsec2. The Holmberg radius was originally measured
by Holmberg (1958MeLu2.136....1H 1958MeLu2.136....1H). Here we have used the Holmberg
radius measured by Hunter & Elmegreen (2006, cat. J/ApJS/162/49), who
converted from photographic magnitudes to B-band magnitudes using the
recipe of de Vaucouleurs et al. (1976srcb.book.....D 1976srcb.book.....D)
Note (4): Measured from V-band images (from Hunter & Elmegreen, 2006,
cat. J/ApJS/162/49).
Note (5): Measured from Hα, normalized to the area π(RD)2, where
RD is the disk scale length (Hunter & Elmegreen, 2004,
cat. J/AJ/128/2170).
Note (6): Determined from GALEX FUV fluxes (Hunter et al., 2010AJ....139..447H 2010AJ....139..447H,
with an update of the GALEX FUV photometry to the GR4/GR5 pipeline
reduction).
Note (7): * = Values determined from the empirical relationship between
oxygen abundance and MB given by Richer & McCall
(1995ApJ...445..642R 1995ApJ...445..642R) and particularly uncertain.
Note (8): Determined from HII regions.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Cl Galaxy class: Im=dwarf irregular;
BCD=Blue Compact Dwarf
5- 13 A9 --- Name Galaxy name
15- 21 F7.2 --- Factor ? Conversion factor for mass estimation
(in units of M☉/(Jy.m.s-1/beam)) (9)
23- 26 F4.2 [Jy.m/s] Flux ? Integrated flux logSν
(in units of (Jy/beam).m/s) (10)
28- 31 F4.2 [Msun] MHI ? Log of the HI mass (logMHI)
--------------------------------------------------------------------------------
Note (9): To convert flux in the ROBUST-weighted integrated HI map to mass in
solar masses. Note this conversion factor contains the necessary
division by the number of pixels per beam, as discussed in Section 4.
Note (10): Measured on the integrated HI map made from the ROBUST-weighted image
cube
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Cl Galaxy class: Im=dwarf irregular;
BCD=Blue Compact Dwarf
5- 13 A9 --- Name Galaxy name
15- 16 I2 h RAh ? Hour of right ascension (J2000)
18- 19 I2 min RAm ? Minute of right ascension (J2000)
21- 24 F4.1 s RAs ? Second of right ascension (J2000)
26 A1 --- DE- Sign of the declination (J2000)
27- 28 I2 deg DEd ? Degree of declination (J2000)
30- 31 I2 arcmin DEm ? Arcminute of declination (J2000)
33- 34 I2 arcsec DEs ? Arcsecond of declination (J2000)
36- 40 F5.1 deg PA [-90/90]? Position angle
42- 45 F4.2 --- b/a ? Minor-to-major axis ratio as measured in an
outer V-band surface brightness isophote
47- 50 F4.1 deg i ? Inclination (11)
--------------------------------------------------------------------------------
Note (11): For computing the inclination of the galaxy, the intrinsic b/a
is assumed to be 0.3 for dwarf galaxies (Hodge & Hitchcock,
1966PASP...78...79H 1966PASP...78...79H; van den Bergh, 1988PASP..100..344V 1988PASP..100..344V).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: refs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Ref Reference number
4- 22 A19 --- BibCode Bibliographic code
24- 47 A24 --- Aut Author's name
49- 67 A19 --- Com Comments
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Sylvain Guehenneux [CDS] 28-Nov-2013