J/ApJ/764/34 HRDS IV. H, He and C radio recombination lines (Wenger+, 2013)
The Green Bank Telescope H II Region Discovery Survey.
IV. Helium and carbon recombination lines.
Wenger T.V., Bania T.M., Balser D.S., Anderson L.D.
<Astrophys. J., 764, 34 (2013)>
=2013ApJ...764...34W 2013ApJ...764...34W
ADC_Keywords: H II regions ; Interstellar medium ; Surveys ; Radio lines
Keywords: ISM: abundances; H II regions; photon-dominated region, PDR; surveys;
techniques: spectroscopic
Abstract:
The Green Bank Telescope H II Region Discovery Survey (GBT HRDS) found
hundreds of previously unknown Galactic regions of massive star
formation by detecting hydrogen radio recombination line (RRL)
emission from candidate H II region targets. Since the HRDS nebulae
lie at large distances from the Sun, they are located in previously
unprobed zones of the Galactic disk. Here, we derive the properties of
helium and carbon RRL emission from HRDS nebulae. Our target sample is
the subset of the HRDS that has visible helium or carbon RRLs. This
criterion gives a total of 84 velocity components (14% of the HRDS)
with helium emission and 52 (9%) with carbon emission. For our highest
quality sources, the average 4He+/H+ abundance ratio by number,
<y+>, is 0.068±0.023(1σ). This is the same ratio as that
measured for the sample of previously known Galactic H II regions.
Nebulae without detected helium emission give robust y+ upper
limits. There are 5 RRL emission components with y+ less than 0.04
and another 12 with upper limits below this value. These H II regions
must have either a very low 4He abundance or contain a significant
amount of neutral helium. The HRDS has 20 nebulae with carbon RRL
emission but no helium emission at its sensitivity level. There is no
correlation between the carbon RRL parameters and the 8um mid-infrared
morphology of these nebulae.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 61 104 Hydrogen Radio Recombination Line parameters
table2.dat 61 84 Helium Radio Recombination Line parameters
table3.dat 61 52 Carbon Radio Recombination Line parameters
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See also:
VIII/58 : A Survey of Radio H II Regions in the Northern Sky (Lockman+ 1989)
J/ApJ/754/62 : HRDS III. HII region kinematic distances (Anderson+, 2012)
J/ApJS/194/32 : The HII Region Discovery Survey (HRDS). II. (Anderson+, 2011)
J/ApJ/738/27 : Galactic HII regions RRL and continuum data (Balser+, 2011)
J/ApJ/690/706 : Distances of Galactic HII regions (Anderson+, 2009)
J/ApJ/670/428 : Bubbles in the galactic disk. II. (Churchwell+, 2007)
J/ApJ/649/759 : Bubbles in the galactic disk (Churchwell+, 2006)
J/ApJ/653/1226 : Physical properties of galactic HII regions (Quireza+, 2006)
J/ApJS/165/338 : Radio recombination lines in HII regions (Quireza+, 2006)
http://www.cv.nrao.edu/hrds/ : The GBT HRDS home page
Byte-by-byte Description of file: table[123].dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- HRDS Source identification (GLLL.lll+B.bbb)
15 A1 --- m_HRDS Multiple velocity component (1)
17 A1 --- n_HRDS [a] a: carbon, but no helium radio recombination
emission (only for table 3)
19- 24 F6.2 mK TL [2/280] Line intensity (TL)
26- 30 F5.2 mK e_TL [0.1/18] Fit uncertainty of TL
32- 36 F5.2 km/s FWHM [2/40] FWHM line width (ΔV)
38- 41 F4.2 km/s e_FWHM [0.04/7] Fit uncertainty of FWHM
43- 49 F7.2 km/s VLSR [-216/117] Line LSR velocity (VLSR)
51- 54 F4.2 km/s e_VLSR [0.03/5] Fit uncertainty of VLSR
56- 59 F4.2 mK rms [0.9/3.4] rms spectral noise in the baseline
regions
61 A1 --- QF [ABC] Quality factor (A: highest quality) (2)
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Note (1): The appended letter flags a specific emission component in an
HII region spectrum that has hydrogen RRLs at several different
LSR velocities. See the Paper II catalog (Anderson et al, 2011,
Cat. J/ApJS/194/32) for further explanations.
Note (2): The quality factor (QF), assigned by eye to each fit, is a
qualitative judgment of the goodness of fit based on the accuracy
of the baseline model, the rms spectral noise, and the presence
of multiple or blended lines which are often difficult to fit.
See section 3 for further explanations.
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History:
From electronic version of the journal
References:
Bania et al. Paper I. 2010ApJ...718L.106B 2010ApJ...718L.106B
Anderson et al. Paper II. 2011ApJS..194...32A 2011ApJS..194...32A Cat. J/ApJS/194/32
Anderson et al. paper III. 2012ApJ...754...62A 2012ApJ...754...62A Cat. J/ApJ/754/62
(End) Emmanuelle Perret [CDS] 23-Oct-2014