J/AJ/116/2246 HII regions in UGCA 86, 92, 105 and UGC 4115 (Kingsburgh+, 1998)
Automatic determination of unbiased luminosity functions for H II regions.
II. Four nearby dwarf galaxies.
Kingsburgh R.L., McCall M.L.
<Astron. J. 116, 2246 (1998)>
=1998AJ....116.2246K 1998AJ....116.2246K (SIMBAD/NED BibCode)
ADC_Keywords: H II regions ; Galaxies, spectra
Keywords: galaxies: individual (UGCA 86, UGCA 92, UGCA 105, UGC 4115 -
galaxies: ISM
Abstract:
Luminosity functions in Hα have been measured for H II regions
in the four dwarf galaxies UGCA 86, UGCA 92, UGCA 105, and UGC 4115
using both the traditional flux measurement method of fixed-threshold
photometry (FTP) and the new method, percentage-of-peak photometry
(PPP). The UGCA galaxies are members of the IC 342-Maffei 1 group.
These two methods give significantly different results in galaxies in
which significant numbers of peaks are associated with H II region
complexes. The work demonstrates that fluxes from FTP can lead to
biased luminosity functions and that PPP should, in general, be
preferred. It is also shown that PPP luminosity functions are not very
sensitive to atmospheric transparency, whereas those constructed from
FTP can be, based on data taken under different atmospheric
conditions. Results to date for six galaxies show that spirals and
dwarfs have luminosity functions of similar shape, which implies that
the distribution of the masses of star formation sites is largely
independent of the mass, and by implication, the metallicity, of the
host galaxy. As measured by PPP, the mean surface brightness of the
lower luminosity H II regions grows as the one-third power of the flux
grows, exactly as predicted for an ensemble in which the gas density
does not vary systematically with the mass of the star cluster. For
the brightest H II regions, however, the relation steepens, which
implies that the most massive star clusters are formed out of the
densest clouds.
Objects:
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RA (2000) DE GLON GLAT Designation(s)
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03 59.8 +67 08 139.8 +10.6 UGCA 86
04 32.0 +63 36 144.7 +13.7 UGCA 92
05 14.3 +62 34 148.5 +13.7 UGCA 105
07 57.0 +14 24 207.0 +20.9 UGC 4115
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 59 65 HII regions in UGCA 86
table4.dat 59 16 HII regions in UGCA 92
table5.dat 59 85 HII regions in UGCA 105
table6.dat 59 17 HII regions in UGC 4115
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Byte-by-byte Description of file: table*.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Galaxy Galaxy name
11- 12 I2 --- [KM98] HII region number in the galaxy (1)
14- 16 I3 --- [HM95] ? Hodge & Miller (1995ApJ...451..176H 1995ApJ...451..176H) number
18- 19 I2 --- [HM95]2 ? Second Hodge & Miller (1995ApJ...451..176H 1995ApJ...451..176H)
number
22- 27 F6.1 arcsec oRA Offset east from reference star (2)
29- 34 F6.1 arcsec oDE Offset north from reference star (2)
36- 38 F3.1 arcsec RadiusPPP ? Radius of circle covering same area as
HII region from PPP (3)
40- 44 F5.2 --- logFluxPPP ? logarithm of total PPP flux relative to
PPP values for HII reference region (3)
46- 49 F4.1 arcsec RadiusFTP ? Radius of circle covering same area as
HII region from FTP (3)
51- 55 F5.2 --- logFluxFTP ? logarithm of total FTP flux relative to
PPP values for HII reference region (3)
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Note (1): [KM98] UGCA NNNN NN in Simbad
Note (2): UGCA 86: reference star: GSC 4076-0876
UGCA 92: reference star: GSC 4069-1252 (see "History" section)
UGCA 105: reference star: GSC 4084-2331 (see "History" section)
UGC 4115: reference star: GSC 0792-0287 (see "History" section)
Note (3): PPP: percentage-of-peak photometry
FTP: fixed-threshold photometry
UGCA 86: reference region: UGCA 86 61
UGCA 92: reference region: UGCA 92 15
UGCA 105: reference region: UGCA 105 16
UGC 4115: reference region: UGC 4115 14
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Table 7: Positions and magnitudes of reference stars
(GSC numbers correctedm see "History" section below)
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Galaxy GSC number RA (2000.0) DE Vmag
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UGCA 86 4076-0876 04 00 01.7 +67 09 11.9 14.06
UGCA 92 4069-1252 04 32 04.5 +63 37 22.4 13.96
UGCA 105 4084-2331 05 14 04.9 +62 36 15.2 15.00
UGC 4115 0792-0287 07 56 41.7 +14 20 31.5 8.16
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History: From AJ electronic version
* 07-May-1999: The GSC numbers of the reference stars were corrected
4069-1522 corrected to 4069-1252, 4084-2577 corrected to 4084-2331,
and 0792-0729 corrected to 0792-0287.
References:
McCall et al., Paper I. 1996AJ....112.1096M 1996AJ....112.1096M
(End) James Marcout, Patricia Bauer [CDS] 19-Jan-1999