J/ApJ/738/27 Galactic HII regions RRL and continuum data (Balser+, 2011)
H II region metallicity distribution in the Milky Way disk.
Balser D.S., Rood R.T., Bania T.M., Anderson L.D.
<Astrophys. J., 738, 27 (2011)>
=2011ApJ...738...27B 2011ApJ...738...27B
ADC_Keywords: H II regions ; Milky Way ; Radio lines ; Radio continuum
Keywords: Galaxy: abundances - H II regions - radio lines: ISM
Abstract:
The distribution of metals in the Galaxy provides important
information about galaxy formation and evolution. HII regions are the
most luminous objects in the Milky Way at mid-infrared to radio
wavelengths and can be seen across the entire Galactic disk. We used
the National Radio Astronomy Observatory (NRAO) Green Bank Telescope
to measure radio recombination line (RRL) and continuum emission in 81
Galactic HII regions. We calculated LTE electron temperatures using
these data. In thermal equilibrium metal abundances are expected to
set the nebular electron temperature with high abundances producing
low temperatures. Our HII region distribution covers a large range of
Galactocentric radius (5-22kpc) and samples the Galactic azimuth range
330-60°. Using our highest quality data (72 objects) we derived an
O/H Galactocentric radial gradient of -0.0383±0.0074dex/kpc.
Combining these data with a similar survey made with the NRAO 140 Foot
telescope we get a radial gradient of -0.0446±0.0049dex/kpc for this
larger sample of 133 nebulae.
Description:
We discuss radio recombination line (RRL) and continuum observations
at X band (8-10GHz) toward 81 Galactic HII regions with the NRAO Green
Bank Telescope (GBT).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 92 81 Properties of Galactic HII regions
table2.dat 68 173 Radio recombination line (RRL) parameters of
Galactic HII regions
table3.dat 93 81 Radio continuum parameters of Galactic HII regions
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See also:
VIII/58 : A Survey of Radio H II Regions in the Northern Sky (Lockman+ 1989)
J/ApJS/194/32 : The HII Region Discovery Survey (HRDS). II. (Anderson+, 2011)
J/ApJ/690/706 : Distances of Galactic HII regions (Anderson+, 2009)
J/A+A/464/909 : JHK photometry near IRAS 06145+1455 (Brand+, 2007)
J/ApJS/165/338 : Radio recombination lines in HII regions (Quireza+, 2006)
J/ApJ/653/1226 : Physical properties of galactic HII regions (Quireza+, 2006)
J/ApJS/162/346 : Abundance gradients in the Galaxy (Rudolph+, 2006)
J/ApJ/582/756 : Velocities of HII regions (Kolpak+, 2003)
J/A+A/397/213 : Galactic HII regions (Paladini+, 2003)
J/ApJ/488/224 : 4.85 GHz fluxes of H II regions (Kuchar+ 1997)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name HII region name
15- 21 F7.3 deg GLON [7/244] Galactic longitude
23- 29 F7.3 deg GLAT [-20/3.5] Galactic latitude
31- 32 I2 h RAh Hour of right ascension (B1950)
34- 35 I2 min RAm Minute of right ascension (B1950)
37- 40 F4.1 s RAs Second of right ascension (B1950)
42 A1 --- DE- Sign of declination (B1950)
43- 44 I2 deg DEd Degree of declination (B1950)
46- 47 I2 arcmin DEm Arcminute of declination (B1950)
49- 52 F4.1 arcsec DEs Arcsecond of declination (B1950)
54- 60 F7.3 deg Az [0/360] Galactocentric azimuth
62- 65 F4.1 kpc Rgal [4.7/21.9] Galactocentric radius
67- 70 F4.1 kpc dsun [0.3/30.3] Distance from the Sun (1)
72- 76 F5.3 --- y [0.017/0.135] Helium abundance ratio by number
78- 82 F5.3 --- e_y y uncertainty
84- 88 I5 K Te [5229/14578] LTE electron temperature
90- 92 I3 K e_Te Te uncertainty
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Note (1): Kinematic distances are derived using the measured source velocity and
a rotation curve model for the Galaxy. For all kinematic distances we
use our measured hydrogen RRL velocities (see Table 2) and the
Brand J. (1986, PhD thesis, Leiden Univ., Netherlands) rotation curve
model. See section 2 for further explanations.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name HII region name
15- 16 A2 --- El Atom (C, H or He)
18- 24 F7.2 mK TL [2.31/9728.44] Peak intensity (TL)
26- 30 F5.2 mK e_TL TL uncertainty
32- 36 F5.2 km/s DelV [1.9/42.2] FWHM line width (ΔV)
38- 41 F4.2 km/s e_DelV DelV uncertainty
43- 49 F7.2 km/s Vlsr [-107.36/89.84] LSR velocity
51- 54 F4.2 km/s e_Vlsr Vlsr uncertainty
56- 60 F5.1 h Tint [2.4/108.8]? Total integration time (1)
62- 66 F5.2 mK rms ? root-mean-square noise of the line free region
68 A1 --- QF [A-D] Data quality (A=excellent; D=poor) (G1)
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Note (1): The integration time listed is derived from the spectral average of
both polarizations of the H87α, H88α, H89α,
H91α, H92α, and H93α transitions.
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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- 13 A13 --- Name HII region name
15- 21 F7.3 K TcRA Peak intensity (TC) for the RA scans
23- 27 F5.3 K e_TcRA TcRA uncertainty
29- 33 F5.3 arcmin TheRA FWHM angular width (Θ) for the RA scans
35- 39 F5.3 arcmin e_TheRA TheRA uncertainty
41- 47 F7.3 K TcDE Peak intensity (TC) for the DEC scans
49- 53 F5.3 K e_TcDE TcDE uncertainty
55- 59 F5.3 arcmin TheDE FWHM angular width (Θ) for the DEC scans
61- 65 F5.3 arcmin e_TheDE TheDE uncertainty
67- 73 F7.3 K Tc [0.092/110.79] Average peak intensity (TC)
75- 79 F5.3 K e_Tc Tc uncertainty
81- 85 F5.3 arcmin Theta [1.3/7.6] Average FWHM angular width (Θ)
87- 91 F5.3 arcmin e_Theta Theta uncertainty
93 A1 --- QF [A-D] Data quality (A=excellent; D=poor) (G1)
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Global notes:
Note (G1): The QF is a measure of data quality taking into account the
signal-to-noise ratio, snr, the baselines, confusion, and the
Gaussian fit. See section 4 for further details.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 11-Jan-2013