J/ApJS/221/26 Radio observations of Galactic WISE HII regions (Anderson+, 2015)
Finding distant Galactic HII regions.
Anderson L.D., Armentrout W.P., Johnstone B.M., Bania T.M., Balser D.S.,
Wenger T.V., Cunningham V.
<Astrophys. J. Suppl. Ser., 221, 26 (2015)>
=2015ApJS..221...26A 2015ApJS..221...26A (SIMBAD/NED BibCode)
ADC_Keywords: H II regions ; Radio continuum ; Interstellar medium
Keywords: Galaxy: structure; H II regions; radio lines: ISM; surveys
Abstract:
The WISE Catalog of Galactic H II Regions contains ∼2000 H II region
candidates lacking ionized gas spectroscopic observations. All
candidates have the characteristic H II region mid-infrared morphology
of WISE 12µm emission surrounding 22µm emission, and
additionally have detected radio continuum emission. We here report
Green Bank Telescope hydrogen radio recombination line (RRL) and radio
continuum detections in the X-band (9GHz; 3cm) of 302 WISE H II region
candidates (out of 324 targets observed) in the zone
225°≥l≥-20°, |b|≤6°. Here we extend the sky coverage of
our H II region Discovery Survey, which now contains nearly 800 HII
regions distributed across the entire northern sky. We provide LSR
velocities for the 302 detections and kinematic distances for 131 of
these. Of the 302 new detections, 5 have (l, b, v) coordinates
consistent with the Outer Scutum-Centaurus Arm (OSC), the most distant
molecular spiral arm of the Milky Way. Due to the Galactic warp, these
nebulae are found at Galactic latitudes >1° in the first Galactic
quadrant, and therefore were missed in previous surveys of the
Galactic plane. One additional region has a longitude and velocity
consistent with the OSC but lies at a negative Galactic latitude
(G039.183-01.422; -54.9km/s). With Heliocentric distances >22kpc and
Galactocentric distances >16kpc, the OSC H II regions are the most
distant known in the Galaxy. We detect an additional three HII regions
near ~=150° whose LSR velocities place them at Galactocentric
radii >19kpc. If their distances are correct, these nebulae may
represent the limit to Galactic massive star formation.
Description:
We draw our targets from the MIR objects in the WISE catalog of
Anderson+, 2014, J/ApJS/212/1. We also include in our sample Sharpless
H II regions (Sharpless 1959, VII/20). See section 2 for further details.
Our observations were made with the GBT 100m telescope from 2012 July
through 2014 August. There are seven radio recombination lines (RRLs)
that can be cleanly observed simultaneously with the GBT in the
X-band: H87α to H93α. We average these seven RRLs (each at
two orthogonal polarizations) to create a single average RRL spectrum.
We followed the same GBT observational procedure as in the original
HRDS (Green Bank Telescope H II Region Discovery Survey (GBT HRDS;
Bania et al. 2010ApJ...718L.106B 2010ApJ...718L.106B).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 70 369 Hydrogen recombination line parameters
for the 302 HII regions
table2.dat 78 302 Radio continuum parameters
table4.dat 64 131 Kinematic distances
--------------------------------------------------------------------------------
See also:
VI/128 : Log of CGPS exposures (Taylor+, 2003-)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
VIII/58 : A Survey of Radio H II Regions in the Northern Sky (Lockman+ 1989)
VII/20 : Catalogue of HII Regions (Sharpless 1959)
J/MNRAS/450/2025 : HIPASS-ZoA HII regions (Alves+, 2015)
J/ApJ/798/L27 : CO obs. of molecular clouds in the 2nd quadrant (Sun+, 2015)
J/ApJS/212/1 : The WISE catalog of Galactic HII regions (Anderson+, 2014)
J/ApJ/764/34 : HRDS IV. H, He and C radio recombination lines (Wenger+, 2013)
J/ApJ/754/62 : HRDS III. HII region kinematic distances (Anderson+, 2012)
J/A+A/537/A1 : Infrared fluxes of HII regions and PNe (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/ApJS/181/255 : CO in Galactic HII regions (Anderson+, 2009)
J/ApJ/690/706 : Distances of Galactic HII regions (Anderson+, 2009)
J/PASJ/59/1185 : Water maser in galactic IRAS sources (Sunada+, 2007)
J/A+A/470/161 : UBV photometry of HII regions exciting stars (Russeil+, 2007)
J/ApJ/653/1226 : Physical properties of galactic HII regions (Quireza+, 2006)
J/ApJS/165/338 : Radio recombination lines in HII regions (Quireza+, 2006)
J/A+A/397/133 : Star-forming complexes in the Galaxy (Russeil+, 2003)
J/ApJ/488/224 : 4.85 GHz fluxes of H II regions (Kuchar+ 1997)
J/A+A/275/67 : Velocity Field of the outer Galaxy (Brand+ 1993)
http://astro.phys.wvu.edu/wise : WISE catalog of Galactic HII regions
http://www.cv.nrao.edu/hrds : GBT HII Region Discovery Survey home page
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Source, GLLL.lll+BB.bbb or
Snnn, Sharpless 1959 (Cat. VII/20)
17 A1 --- m_Name Source Velocity Component (a,b,c) (G1)
19- 25 F7.3 deg GLON Galactic Longitude, Source
27- 32 F6.3 deg GLAT Galactic Latitude, Source
34- 39 F6.1 mK TL [2.5/2047] Hydrogen Radio Recombination
Line Intensity
41- 43 F3.1 mK e_TL [0.1/6] Uncertainty in TL, 1σ
45- 48 F4.1 km/s FWHM [7.8/55.5] FWHM line width
50- 52 F3.1 km/s e_FWHM [0.1/6] Uncertainty in FWHM, 1σ
54- 59 F6.1 km/s VLSR [-211.6/136.2] Local Standard of Rest Velocity
61- 63 F3.1 km/s e_VLSR [0.1/3.2] Uncertainty in VLSR, 1σ
65- 68 F4.1 mK rms [1/11.7] Observation r.m.s. noise
70 A1 --- Note [*] Note (1)
--------------------------------------------------------------------------------
Note (1):
* = Discrete HII region velocity for sources with multiple velocity
component spectra.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Source identification (GLLL.lll+BB.bbb)
17- 23 F7.3 deg GLON Galactic longitude, Source
25- 30 F6.3 deg GLAT Galactic latitude, Source
32- 36 I5 mK TRA [33/34987]? Peak intensity in RA scan direction
38- 40 I3 mK e_TRA [2/448]? Uncertainty in TRA
42- 46 I5 mK TDec [27/35718]? Peak intensity in DE scan direction
48- 50 I3 mK e_TDec [2/225]? Uncertainty in TDec
52- 54 I3 arcsec ASRA [48/927]? FWHM angular size in RA scan direction
56- 58 I3 arcsec e_ASRA [1/203]? Uncertainty in ASRA
60- 62 I3 arcsec ASDec [47/887]? FWHM angular size in DE scan direction
64- 65 I2 arcsec e_ASDec [1/43]? Uncertainty in ASDec
67- 71 I5 mJy S [8/28327]? GBT integrated flux density at 8665MHz
73- 76 I4 mJy e_S [5/2553]? Uncertainty in S
78 A1 --- Note [CP] Continuum emission morphology;
data quality (1)
--------------------------------------------------------------------------------
Note (1): Comments concerning continuum emission morphology and data quality
as follows:
C = Complex: Source has complex continuum structure; this single Gaussian
component model only crudely represents the true source characteristics.
P = Peaked: Continuum peak lies within 10 arcsec of the nominal target
position. These are the highest quality continuum data.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Source, GLLL.lll+BB.bbb or
Snnn, Sharpless 1959 (Cat. VII/20)
17 A1 --- m_Name Source Velocity Component (a,b) (G1)
19- 23 F5.1 km/s VLSR [-99.1/106] Local Standard of Rest Velocity
25- 27 F3.1 kpc Dnear [0.4/7.1]? Near distance
29- 32 F4.1 kpc Dfar [2.7/23.5]? Far distance
34- 36 F3.1 kpc Dtan [2.2/8.4]? Tangent point distance
38- 41 F4.1 kpc RGal [3.8/25.3] Galactocentric radius
43- 48 F6.1 km/s VTP [-170/169]? Tangent point velocity
50 A1 --- KDAR [FNOT] Kinematic distance ambiguity
resolution (1)
52- 55 F4.1 kpc Dist [2.3/23.5] Derived heliocentric distance
57- 59 F3.1 kpc e_Dist [0/5.5] Uncertainty in Dist
61- 64 I4 pc Zdist [-499/778] Distance from Galactic plane
--------------------------------------------------------------------------------
Note (1): Kinematic distance ambiguity resolution (KDAR) as follows:
N = near distance;
F = far distance;
O = outer Galaxy source;
T = tangent point distance.
--------------------------------------------------------------------------------
Global notes:
Note (G1): For sources with multiple velocity components detected along the
line of sight, the source names are given additional letters, "a", "b",
"c", in order of decreasing peak line intensity.
--------------------------------------------------------------------------------
Nomenclature note:
GLLL.lll+BB.bbb sources are <[ABB2014] WISE GLLL.ll+BB.bbb> in Simbad and
Snnn are <Sh 2-NNN> in Simbad.
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 29-Jan-2016