J/MNRAS/450/2025 HIPASS-ZoA HII regions (Alves+, 2015)
The HIPASS survey of the Galactic plane in radio recombination lines.
Alves M.I.R., Calabretta M., Davies R.D., Dickinson C., Staveley-Smith L.,
Davis R.J., Chen T., Barr A.
<Mon. Not. R. Astron. Soc., 450, 2025-2042 (2015)>
=2015MNRAS.450.2025A 2015MNRAS.450.2025A (SIMBAD/NED BibCode)
ADC_Keywords: Galactic plane ; H II regions ; Morphology ; Radio lines
Keywords: radiation mechanisms: general - methods: data analysis - HII regions -
ISM: lines and bands - Galaxy structure - radio lines: ISM
Abstract:
We present a Radio Recombination Line (RRL) survey of the Galactic
plane from the Hi Parkes All-sky Survey and associated Zone of
Avoidance survey, which mapped the region l=196°-0°-52°
and |b|≤5° at 1.4GHz and 14.4-arcmin resolution. We combine three
RRLs, H168α, H167α, and H166α to derive fully
sampled maps of the diffuse ionized emission along the inner Galactic
plane. The velocity information, at a resolution of 20km/s, allows us
to study the spatial distribution of the ionized gas and compare it
with that of the molecular gas, as traced by CO. The
longitude-velocity diagram shows that the RRL emission is mostly
associated with CO gas from the molecular ring and is concentrated
within the inner 30° of longitude. A map of the free-free emission
in this region of the Galaxy is derived from the line-integrated RRL
emission, assuming an electron temperature gradient with
Galactocentric radius of 496±100K/kpc. Based on the thermal
continuum map, we extracted a catalogue of 317 compact (≲15-arcmin)
sources, with flux densities, sizes, and velocities. We report the
first RRL observations of the southern ionized lobe in the Galactic
Centre. The line profiles and velocities suggest that this
degree-scale structure is in rotation. We also present new evidence of
diffuse ionized gas in the 3-kpc arm. Helium and carbon RRLs are
detected in this survey. The He line is mostly observed towards HII
regions, whereas the C line is also detected further away from the
source of ionization. These data represent the first observations of
diffuse C RRLs in the Galactic plane at a frequency of 1.4GHz.
Description:
The results presented in this paper use a combination of the HIPASS
(Staveley-Smith, 1996PASA...13..187S 1996PASA...13..187S) and ZOA (Staveley-Smith et al.,
1998AJ....116.2717S 1998AJ....116.2717S) data sets for the Galactic plane region
l=196°-0°-52° and |b|≤5°.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 101 317 List of 317 HII regions in the range
l=196°-0°-52° and |b|≤5°,
extracted from the thermal continuum map of
Fig. 7 using Sextractor
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See also:
VIII/73 : HI Parkes All Sky Survey Catalogue (HIPASS) (Meyer+, 2004)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Sequential number
5- 10 F6.2 deg GLON Galactic longitude
12- 16 F5.2 deg GLAT Galactic latitude
18- 21 F4.1 arcmin amaj ?=- Semi-major axis
23- 26 F4.1 arcmin bmin ?=- Semi-minor axis
28- 30 I3 deg PA []?=- Position angle measured counterclockwise
between the semimajor axis of the source
and the longitude axis
32- 36 F5.1 Jy Sp Peak flux at 1.4GHz (in Jy/beam)
38- 41 F4.1 Jy e_Sp Error in peak flux (in Jy/beam)
43- 47 F5.1 Jy S Integrated flux at 1.4GHz
49- 52 F4.1 Jy e_S Error in integrated flux
54- 59 F6.1 km/s V1 RRL central velocity from a one- or
two-component Gaussian fit
61- 66 F6.1 km/s V2 ?=- Second RRL central velocity from a
two-component Gaussian fit
68 I1 --- Flag Flag parameter (1)
70-101 A32 --- Notes General remarks on the source (2)
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Note (1): Flag parameter as follows:
2 = the source was originally blended with another one
8 = the source is truncated owing to its proximity to the image boundary
Note (2): These are taken from Paladini et al. (2003, Cat. J/A+A/397/213) and
follow the definitions given by Kuchar & Clark (1997, Cat. J/ApJ/488/224) to
define if a source is:
C, in a complex field;
S, with a strong source nearby;
X, with a strong source nearby (<10Jy), radio or optical counterpart.
The value within the square brackets corresponds to the number of sources
in the Paladini et al. (2003, Cat. J/A+A/397/213) catalogue that match a
given source in this survey.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 10-Dec-2015