J/ApJ/753/62 Kinematic distance ambiguity in HII regions (Jones+, 2012)
Kinematic distance assignments with H I absorption.
Jones C., Dickey J.M.
<Astrophys. J., 753, 62 (2012)>
=2012ApJ...753...62J 2012ApJ...753...62J
ADC_Keywords: H II regions ; H I data ; Infrared sources ; Radio sources
Keywords: Galaxy: structure; H II regions
Abstract:
Using H I absorption spectra from the International Galactic Plane
Survey, a new method is implemented to resolve the kinematic distance
ambiguity for 75 H II regions with known systemic velocities from
radio recombination lines. A further 40 kinematic distance
determinations are made for H II region candidates without known
systemic velocities through an investigation of the presence of H I
absorption around the terminal velocity. New kinematic distance
determinations can be used to further constrain spiral arm parameters
and the location and extent of other structures in the Milky Way disk.
H I absorption toward continuum sources beyond the solar circle is
also investigated. Follow-up studies of H I at higher resolution than
the 1' to 2' of existing Galactic Plane Surveys will provide kinematic
distances to many more H II regions on the far side of the Galactic
center. On the basis of the velocity channel summation technique
developed in this paper, a much larger sample of H II regions will be
analyzed in a future paper to remove the near-far distance ambiguity.
Description:
This paper makes use of radio and infrared archival data. Radio
continuum and emission/absorption spectra are extracted from the VLA
Galactic Plane Survey (VGPS; Stil et al. 2006AJ....132.1158S 2006AJ....132.1158S) and
Southern Galactic Plane Survey (SGPS; McClure-Griffiths et al.
2005ApJS..158..178M 2005ApJS..158..178M), two components of the International Galactic
Plane Survey (IGPS). While the Wide-field Infrared Survey Explorer
(WISE; Wright et al. 2010AJ....140.1868W 2010AJ....140.1868W) and Spitzer Galactic Legacy
Infrared Mid-Plane Survey Extradinordinarie (GLIMPSE; Benjamin et al.
2003PASP..115..953B 2003PASP..115..953B) provide infrared image cutouts used in Section 7.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 131 185 Kinematic distance ambiguity resolutions (KDARs)
from velocity channel summations ΣSch
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See also:
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
II/293 : GLIMPSE Source Catalog (I + II + 3D) (IPAC 2008)
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/626/887 : HI clouds in Southern Galactic Plane Survey (Kavars+, 2005)
J/ApJS/154/553 : Inner galaxy massive star formation regions (Sewilo+, 2004)
J/ApJ/582/756 : Velocities of HII regions (Kolpak+, 2003)
J/A+A/171/261 : RRLs of Southern HII Regions (Caswell+ 1987)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 7 F7.3 deg GLON Galactic longitude of the source (1)
9- 14 F6.3 deg GLAT Galactic latitude of the source (1)
16- 19 F4.2 --- Bnoise [0.07/0.5]? Baseline noise of the absorption
spectrum (σ(e-τ))
21- 23 I3 K Tcont [8/503]? Continuum temperature of the "on"
source pixel
25- 31 F7.2 km/s Vterm [-141/126.1]? Terminal velocity (VT)
33 A1 --- f_Vrrl [DT] Double or Triple sources (2)
35- 40 F6.1 km/s Vrrl [-122/115]? Velocity from radio recombination
lines (VRRL) (3)
42- 46 A5 --- Ref Reference for velocities (4)
48- 52 F5.2 --- Svel [-9/50]? Summation of velocity interval
S(VRRL) to VT for Case III HII regions (5)
54- 57 F4.2 --- e_Svel [0.5/4.1]? Svel uncertainty
59- 64 F6.2 --- Sin [4.6/144.3]? Sch for the whole inner Galaxy
66- 69 F4.2 --- e_Sin [0.6/4.6]? Sin uncertainty
71- 75 F5.2 --- Stp [-5.5/55.1]? Sch for the tangent point
interval
77- 80 F4.2 --- e_Stp [0.3/2.4]? Stp uncertainty
82- 86 F5.2 --- Sout [-9.2/24.9]? Sch for the outer Galaxy
88- 91 F4.2 --- e_Sout [0.6/4]? Sout uncertainty
93- 96 A4 --- KDAR KDAR determination (6)
98-102 F5.2 kpc dGR [2.8/12.3]? Galactic radius distance (dGR)
104-107 F4.2 kpc E_dGR [0.2/2.7]? Positive error on dGR
109-112 F4.2 kpc e_dGR [0.3/2.1]? Negative error on dGR
114-118 F5.2 kpc dlos [2/19.5]? Kinematic distance (dlos) (7)
120-123 F4.2 kpc E_dlos [0.5/2.6]? Positive error on dlos (7)
125-128 F4.2 kpc e_dlos [0.02/2.3]? Negative error on dlos (7)
130-131 A2 --- n_dlos [*f ] Remarks on dlos (8)
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Note (1): Galactic coordinates of the source - corresponding to the location of
the highest continuum temperature (see Section 3).
Note (2): Sources with (multiple) double or triple RRL velocity component
profiles are denoted by "D" and "T," respectively.
Note (3): Velocities from "Urq11" (Urquhart et al. 2012MNRAS.420.1656U 2012MNRAS.420.1656U) are
derived from 13CO emission.
Note (4): Reference as follows:
Ar02 = Araya et al. 2002ApJS..138...63A 2002ApJS..138...63A
ARM00 = Argon et al. 2000ApJS..129..159A 2000ApJS..129..159A
CH87 = Caswell & Haynes 1987, Cat. J/A+A/171/261
GG76 = Georgelin & Georgelin 1976A&A....49...57G 1976A&A....49...57G
GBT11 = Anderson et al. 2011, Cat. J/ApJS/194/32 (GBTRS)
L81 = Lockman 1981ApJ...245..459L 1981ApJ...245..459L
L89 = Lockman 1989, Cat. VIII/58
LPH96 = Lockman et al. 1996ApJ...472..173L 1996ApJ...472..173L
Sw04 = Sewilo et al. 2004, Cat. J/ApJS/154/553
Urq11 = Urquhart et al. 2012MNRAS.420.1656U 2012MNRAS.420.1656U
W70 = Wilson et al. 1970A&A.....6..364W 1970A&A.....6..364W
Note (5): note S(VRRL) to VT is not measured for regions located at the
tangent point.
Note (6): KDAR (Kinematic Distance Ambiguity Resolution) as follows:
N = near side;
N-TP = located before the tangent point;
TP = tangent point;
TP-F = located at least as far as the tangent point;
F = far side;
O = outer Galaxy;
EG = extragalactic;
? = uncertain.
Note (7): Errors are consistent with uncertainties of 15km/s in velocity for
HII regions located in the inner Galaxy, and 20km/s for the outer
Galaxy. See Figure 7 for kinematic locations.
Note (8): Remarks on the dlos computation (see section 8):
* = Distances marked with an asterisk (*) are based on the last velocity
which shows absorption in the outer Galaxy; except in the case of
G26.610-0.210 (f)
f = the GBTHRDS (Green Bank Telescope HII Region Discovery Survey, Anderson
et al. 2011, Cat. J/ApJS/194/32) has three RRL velocities listed, one
of which is negative (-35.7km/s).
** = Distances marked with a double asterisk (**) are based on poor quality
KDARs.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 12-Feb-2014