J/MNRAS/495/3592 Emission in local volume dwarf galaxies (Karachentsev+, 2020)
Statistics and properties of emission-line regions in the local volume dwarf
galaxies.
Karachentsev I.D., Kaisin S.S.
<Mon. Not. R. Astron. Soc., 495, 3592-3601 (2020)>
=2020MNRAS.495.3592K 2020MNRAS.495.3592K (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, dwarf ; Galaxies, nearby ; Star Forming Region ;
Optical ; Infrared ; Ultraviolet
Keywords: galaxies: dwarf - galaxies: star formation - galaxies: statistics
Abstract:
We used the Hα images from a large sample of nearby late-type
dwarf galaxies to investigate properties of their emission structure.
The sample consists of 300 galaxies of the irregular (Irr), Magellanic
irregular (Im), blue compact dwarf (BCD), and transition (Tr) types
situated within a distance of 11Mpc. In each galaxy, we indicated the
number of compact HII regions, the presence of bubble-like or
filament-like structures, the presence of a faint diffuse emission,
and a sign of the global burst. The larger the luminosity of a galaxy,
the greater number of compact HII sources in it. The integral and
specific star formation rates (SFRs) of the dwarf increase steeply
with the increase of the number of HII regions showing the evidence of
the epidemic character of the star formation process. The dwarf
galaxies with emission-line bubbles, or filaments, or signs of the
global star formation burst have approximately the same
hydrogen-mass-to-luminosity ratio as that of the whole sample objects.
However, their mean SFR is significantly higher than that of other
galaxies in the sample. Emission bubble-like structures are found in
the nearby dwarfs with a frequency of one case per four to five
galaxies. Their linear diameters are close to those expected for
supernova remnants. The mean specific SFR for the nearby late-type
dwarfs is close to the Hubble parameter, H0=-10.14dex/yr, consistent
with the sluggish cosmic star formation history of galaxies of this
kind.
Description:
At present, the most representative sample of dwarf galaxies is the
Updated Nearby Galaxy Catalogue (UNGC; Karachentsev, Makarov & Kaisina
2013AJ....145..101K 2013AJ....145..101K, Cat. J/AJ/145/101), which comprises more than 800
galaxies with distances within 11Mpc. The refined and updated version
of the UNGC is available in the data base available at
http://www.sao.ru/lv/lvgdb. Over the past decade, systematic
observations of the local volume (LV) galaxies (D<11Mpc) in the
Hα emission line and in the red continuum have been carried out
with the 6-m BTA telescope of the Special Astrophysical Observatory of
the Russian Academy of Sciences (SAO RAS). These observations are
described in a number of papers including the most recent
(Karachentsev, Kaisin & Kaisina 2015Ap.....58..453K 2015Ap.....58..453K; Kaisin &
Karachentsev 2019AstBu..74....1K 2019AstBu..74....1K) and references therein.
Our collection contains images in the Hα emission line for 309
late-type dwarf galaxies with distances within 11Mpc. We estimated
average characteristics of dwarf galaxies: the linear diameter, the
integral luminosity, the hydrogen mass, the integral and specific SFRs
depending on the galaxy morphological type (BCD, Irr + Im, or Tr), the
number of compact HII regions, and the presence of various emission
details of the structure (bubbles, filaments, diffuse emission, and a
global burst).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 72 309 Observational data on 309 LV dwarf galaxies
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See also:
J/AJ/145/101 : Updated nearby galaxy catalog (Karachentsev+, 2013)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Name Galaxy name
19- 21 A3 --- Morph Morphological type (1)
23- 27 F5.2 Mpc Dist Distance
29- 33 F5.2 kpc A26 Linear diameter measured within the
Holmberg isophote
35- 39 F5.2 mag/arcsec2 SB Surface brightness in the B-band
within the Holmberg diameter
41- 44 F4.2 [Lsun] logLK Logarithm of the integral luminosity
in the K-band (2)
46- 49 F4.2 [Msun] logMHI ? Logarithm of the neutral hydrogen
mass
51- 55 F5.2 [Msun/yr] logSFRHa Logarithm of the integral
star-formation rate determined via the
Hα flux (3)
57- 61 F5.2 [Msun/yr] logSFRFUV ? Logarithm of the integral
star-formation rate determined via the
FUV-band flux (4)
63- 64 I2 --- NC Number of compact emission knots
66 I1 --- NB Number of bubbles
68 I1 --- Fil [0/1] Presence or absence of
filament-like structures
70 I1 --- Dif [0/1] Presence or absence of a diffuse
emission
72 I1 --- GBE [0/1] Presence or absence of the
global bright emission
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Note (1): Morphological type as follows:
BCD = Blue compact dwarf (51/309)
Im = Magellanic irregular (32/309)
Ir = Irregular (210/309)
Tr = Transition (16/309)
Note (2): K-band photometry is usually poorly constrained for dwarf galaxies
with the 2MASS survey (Jarrett et al. 2000AJ....119.2498J 2000AJ....119.2498J,
2003AJ....125..525J 2003AJ....125..525J): actually, only a quarter of galaxies in our
sample have Ks data from 2MASS; for the remaining 3/4 dwarf
galaxies, their K-magnitudes were determined via apparent B-magnitudes
and the average colour index <B-K≥2.35 according to Jarrett et al.
(2003AJ....125..525J 2003AJ....125..525J), and, under such approach, a typical error in
LK luminosity is about 0.2dex.
Note (3): The logarithm of the integral star formation rate is determined
according to Kennicutt (1998ARA&A..36..189K 1998ARA&A..36..189K) as:
log[SFR]Hα=logFc(Hα)+2logD+8.98, where D is the
distance (in Mpc) and Fc(Hα) is the integral flux in the
Hα line corrected for the internal and Galactic extinction
Note (4): The logarithm of the integral SFR is determined from the ultraviolet
flux in the FUVband, Fc(FUV), corrected for the extinction
according to Lee et al. (2011ApJS..192....6L 2011ApJS..192....6L, Cat. J/ApJS/192/6):
log[SFR]u=logFc(FUV)+2logD-6.78, where D is the distance (in Mpc)
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 20-Jun-2023