J/ApJS/234/33 A GBT survey of large Galactic HII regions (Anderson+, 2018)
A Green Bank Telescope survey of large Galactic HII regions.
Anderson L.D., Armentrout W.P., Luisi M., Bania T.M., Balser D.S.,
Wenger T.V.
<Astrophys. J. Suppl. Ser., 234, 33 (2018)>
=2018ApJS..234...33A 2018ApJS..234...33A
ADC_Keywords: H II regions ; Radio lines ; Infrared sources
Keywords: Galaxy: structure; H II regions; radio lines: ISM; surveys
Abstract:
As part of our ongoing HII Region Discovery Survey (HRDS), we report
the Green Bank Telescope detection of 148 new angularly large Galactic
HII regions in radio recombination line (RRL) emission. Our targets
are located at a declination of δ>-45°, which corresponds to
266°>l>-20° at b=0°. All sources were selected from the
Wide-field Infrared Survey Explorer Catalog of Galactic HII Regions,
and have infrared angular diameters ≥260". The Galactic distribution
of these "large" HII regions is similar to that of the previously
known sample of Galactic HII regions. The large HII region RRL line
width and peak line intensity distributions are skewed toward lower
values, compared with that of previous HRDS surveys. We discover seven
sources with extremely narrow RRLs <10km/s. If half the line width is
due to turbulence, these seven sources have thermal plasma
temperatures <1100K. These temperatures are lower than any measured
for Galactic HII regions, and the narrow-line components may arise
instead from partially ionized zones in the HII region
photodissociation regions. We discover G039.515+00.511, one of the
most luminous HII regions in the Galaxy. We also detect the RRL
emission from three HII regions with diameters >100pc, making them
some of the physically largest known HII regions in the Galaxy. This
survey completes the HRDS HII region census in the Northern sky, where
we have discovered 887 HII regions and more than doubled the size of
the previously known census of Galactic HII regions.
Description:
We draw our targets from the WISE Catalog of Galactic HII Regions
(Anderson+ 2014, J/ApJS/212/1), which lists ∼2500 HII region
candidates identified from WISE data (Wright+ 2010AJ....140.1868W 2010AJ....140.1868W ;
see II/311) that have associated radio continuum emission. As in
Anderson+ (2015, J/ApJS/221/26), we also include in our sample
Sharpless HII regions not yet observed in RRL emission.
We observe our targets using the 100m Green Bank Telescope (GBT) at
C-band (4-8GHz).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 65 201 Hydrogen Recombination Line parameters
table2.dat 65 21 Helium Recombination Line parameters
table3.dat 65 16 Carbon Recombination Line parameters
table4.dat 61 45 Kinematic distances
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See also:
II/249 : WHAM Northern Sky Survey, V-1.1 (Haffner+, 2003)
VI/128 : Log of CGPS exposures (Taylor+, 2003-)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
J/A+A/171/261 : RRLs of Southern HII Regions (Caswell+ 1987)
J/A+A/275/67 : Velocity Field of the outer Galaxy (Brand+ 1993)
J/ApJS/165/338 : Radio recombination lines in HII regions (Quireza+, 2006)
J/ApJ/690/706 : Distances of Galactic HII regions (Anderson+, 2009)
J/ApJS/181/255 : CO in Galactic HII regions (Anderson+, 2009)
J/ApJ/709/424 : HII regions identified with WMAPS and GLIMPSE (Murray+, 2010)
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/753/62 : Kinematic distance ambiguity in HII regions (Jones+, 2012)
J/ApJ/754/62 : HRDS III. HII region kinematic distances (Anderson+, 2012)
J/ApJ/764/34 : HRDS IV. H, He and C radio recombination lines (Wenger+, 2013)
J/ApJ/774/117 : HII region kinematic distances (Jones+, 2013)
J/ApJS/212/1 : The WISE catalog of Galactic HII regions (Anderson+, 2014)
J/ApJS/221/26 : Radio obs. of Galactic WISE HII regions (Anderson+, 2015)
J/ApJ/810/42 : Hydrogen RRL parameters of H II regions (Anderson+, 2015)
J/MNRAS/450/2025 : HIPASS-ZoA HII regions (Alves+, 2015)
J/A+A/588/A97 : Continuum sources from the THOR survey (Bihr+, 2016)
http://www.cv.nrao.edu/hrds/ : HII Region Discovery Survey 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- 15 A15 --- ID Source identifier
16 A1 --- m_ID [abc] Multiple component (1)
18- 24 F7.3 deg GLON Galactic longitude
26- 31 F6.3 deg GLAT Galactic latitude
33- 37 F5.1 mK TL [1.8/145] Line intensity; Antenna temperature
39- 41 F3.1 mK e_TL [0.1/1.4] Uncertainty in TL
43- 46 F4.1 km/s DelV [1.2/55.4] Full-Width at Half Maximum line width
ΔV
48- 50 F3.1 km/s e_DelV [0.1/2.7] Uncertainty in DelV
52- 57 F6.1 km/s VLSR [-131.1/151.5] Local Standard of Rest velocity
59- 61 F3.1 km/s e_VLSR [0.1/1.2] Uncertainty in VLSR
63- 65 F3.1 mK rms [0.7/2.5] Root mean square noise in spectrum
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Note (1): Source names for HII regions with multiple detected hydrogen RRL
components are appended by "a", "b", or "c", in order of decreasing
hydrogen RRL intensity.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- ID Source identifier
17- 21 F5.1 km/s VLSR [-83.5/103.3] Local Standard of Rest velocity
23- 25 F3.1 kpc DN [2.3/7.2]? Near point distance
27- 30 F4.1 kpc DF [2.5/17.4] Far point distance
32- 34 F3.1 kpc DT [2.5/7.4]? Tangent point distance
36- 39 F4.1 kpc RGal [4.4/25.1] Galactocentric radius
41- 45 F5.1 km/s VTP [12.6/108]? Tangent point velocity
47 A1 --- KDAR Kinematic distance ambiguity resolution
(T: tangent point distance;
O: outer Galaxy source)
49- 52 F4.1 kpc Dist [2.5/17.4] Heliocentric distance
54- 56 F3.1 kpc e_Dist [0/5.4] Dist uncertainty (1)
58- 61 I4 pc Z [-600/379] Vertical distance, Z, from
the Galactic mid-plane
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Note (1): The Heliocentric distance uncertainty computed from the
Anderson et al. (2014, J/ApJS/212/1) model.
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Nomenclature notes:
HII region candidates in Anderson+ 2014, J/ApJS/212/1 are
<[ABB2014] WISE GLLL.lll+BB.bbb> in Simbad.
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 23-Mar-2018