J/MNRAS/492/895 Ultracompact HII regions extended emission (de la Fuente+, 2020)
Ultracompact H II regions with extended emission: the complete view.
de la Fuente E., Porras A., Trinidad M.A., Kurtz S.E., Kemp S.N.,
Tafoya D., Franco J., Rodriguez-Rico C.
<Mon. Not. R. Astron. Soc., 492, 895-914 (2020)>
=2020MNRAS.492..895D 2020MNRAS.492..895D (SIMBAD/NED BibCode)
ADC_Keywords: H II regions ; Radio continuum ; Interstellar medium
Keywords: stars: pre-main-sequence - ISM: bubbles - HII regions -
radio continuum: ISM
Abstract:
In this paper, we present the results of a morphological study
performed on a sample of 28 ultracompact HII (UC HII) regions located
near extended free-free emission, using radio continuum (RC)
observations at 3.6cm with the C and D Very Large Array (VLA)
configurations, with the aim of determining a direct connection
between them. By using previously published observations in B and D
VLA configurations, we compiled a final catalogue of 21 UC HII regions
directly connected with the surrounding extended emission (EE). The
observed morphology of most of the UC HII regions in RC emission is
irregular (single- or multipeaked sources) and resembles a classical
bubble structure in the Galactic plane with well-defined cometary
arcs. RC images superimposed on colour composite Spitzer images
reinforce the assignations of direct connection by the spatial
coincidence between the UC components and regions of saturated 24µm
emission. We also find that the presence of EE may be crucial to
understand the observed infrared excess because an underestimation of
ionizing Lyman photons was considered in previous works (e.g. Wood &
Churchwell; Kurtz, Churchwell & Wood).
Description:
The sources targeted in our VLA observations were selected according
to the following criteria: (i) following Wood & Churchwell
(1989ApJS...69..831W 1989ApJS...69..831W) and Kurtz et al. (1994ApJS...91..659K 1994ApJS...91..659K, Cat.
J/ApJS/91/659), the sources must exhibit UC HII region colours with IR
excess in their IRAS fluxes and (ii) the sources must have EE
associated with the UC HII region in either Kurtz et al.
(1999ApJ...514..232K 1999ApJ...514..232K, 3.6cm VLA configuration D) or Kim & Koo
(2001ApJ...549..979K 2001ApJ...549..979K, 21cm VLA configuration DnC) observations. The
resulting sample consists of 28 UC HII+ EE regions and they are listed
in Table 1.
Snapshot-mode interferometric observations were carried out with the
VLA of the National Radio Astronomy Observatory (NRAO) in the C and D
configurations. Continuum emission at 3.6cm was observed in the C
configuration (VLA-C) on 1998 December 1st and 13th, and in the D
configuration (VLA-D) on 2005 April 3rd. The total on-source
integration times were ∼9.5min for the VLA-C observations and ∼15min
for the VLA-D observations. The total spectral bandwidth was
δν=50MHz for all the observations. As mentioned above, a
total of 28 regions were targeted, of which 15 were observed with the
VLA-D, 12 with the VLA-C, and one source was observed in both
configurations.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 57 28 The sample of 28 ultracompact HII regions with
extended emission
table2.dat 54 53 VLA observational parameters and UC HII fluxes
table3.dat 49 14 Combined multiconfiguration VLA image parameters
table4.dat 40 28 Results from morphological study of extended
emission
table5.dat 68 21 The final catalogue of UC HII + EE
table6.dat 55 39 Results on the energetics for the initial sample
table7.dat 53 26 Energetics results for the final catalogue
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See also:
J/ApJS/91/659 : Ultracompact HII regions radio images (Kurtz+ 1994)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Name Name of the HII region (GLLL.ll+BB.bb)
14 A1 --- f_Name [c] Flag on Name (G1)
16- 26 A11 --- OName IRAS name of the HII region (HHMMm+DDMMA)
28- 29 I2 h RAh Right ascension (J2000) (1)
31- 32 I2 min RAm Right ascension (J2000) (1)
34- 38 F5.2 s RAs Right ascension (J2000) (1)
40 A1 --- DE- Declination sign (J2000) (1)
41- 42 I2 deg DEd Declination (J2000) (1)
44- 45 I2 arcmin DEm Declination (J2000) (1)
47- 50 F4.1 arcsec DEs Declination (J2000) (1)
52- 55 F4.1 kpc Dist Distance
57 I1 --- r_Dist [1/6] Reference for Dist (2)
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Note (1): Right ascension and Declination were precessed from 1950 coordinates
of Wood & Churchwell (1989ApJS...69..831W 1989ApJS...69..831W) and
Kurtz et al. (1994ApJS...91..659K 1994ApJS...91..659K, Cat. J/ApJS/91/659) papers
Note (2): References as follows:
1 = Wood & Churchwell (1989ApJS...69..831W 1989ApJS...69..831W)
2 = Churchwell, Walmsley & Cesaroni (1990A&AS...83..119C 1990A&AS...83..119C)
3 = Kurtz et al. (1994ApJS...91..659K 1994ApJS...91..659K, Cat. J/ApJS/91/659)
4 = Watson et al. (1997ApJ...487..818W 1997ApJ...487..818W)
5 = Kurtz et al. (1999ApJ...514..232K 1999ApJ...514..232K)
6 = Araya et al. (2002ApJS..138...63A 2002ApJS..138...63A, Cat. J/ApJS/138/63)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Name Name of the HII region (GLLL.ll+BB.bb)
14 A1 --- f_Name [c] Flag on Name (G1)
16- 26 A11 --- OName IRAS name of the HII region (HHMMm+DDMMA)
28 A1 --- VLA [BCD] VLA configuration (1)
30- 34 F5.2 Jy Snu Integrated flux density (2)
36- 40 F5.2 arcsec Beam1 Beam size, major axis
42- 45 F4.2 arcsec Beam2 Beam size, minor axis
47- 49 I3 deg PA [] Position angle
51- 54 F4.2 mJy/beam rms Observational rms
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Note (1): For those sources observed with the VLA configuration C, VLA
configurations B and D images were recreated using data from
Kurtz et al. (1994ApJS...91..659K 1994ApJS...91..659K, Cat. J/ApJS/91/659) and
Kurtz et al. (1999ApJ...514..232K 1999ApJ...514..232K), respectively
Note (2): UC HII integrated flux densities were obtained using suitable boxes
covering the whole RC emission above 3 times the noise level
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Name Name of the HII region (GLLL.ll+BB.bb)
14 A1 --- f_Name [c] Flag on Name (1)
16- 25 A10 --- OName IRAS name of the HII region (HHMMm+DDMMA)
27- 29 A3 --- VLA VLA configurations combined to produce the
MRIs
31- 34 F4.2 arcsec Beam1 Beam size, major axis
36- 39 F4.2 arcsec Beam2 Beam size, minor axis
41- 43 I3 deg PA [] Position angle
45- 49 F5.3 mJy/beam rms Observational rms
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Note (1): Flag as follows:
c = The MRI of G19.60-0.23 is not shown in Fig. 2 but is shown superimposed
on the Spitzer image in Fig. 3.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Name Name of the HII region (GLLL.ll+BB.bb)
14 A1 --- EE [YN] Presence of extended emission
(Y:yes, N:No)
16 A1 --- ConEElit [YPUN-] Indicates if there is a direct
connection between the UC HII region and
the large-scale extended emission
(literature) (1)
18 I1 --- r_ConEElit [1/3]? Reference for ConEElit (2)
20 A1 --- ConEEtw [YPN] Indicates if there is a direct
connection between the UC HII region and
the large-scale extended emission
(this work) (1)
22- 24 F3.1 arcmin EEsize1 Extended emission size (x-axis) (3)
26- 28 F3.1 arcmin EEsize2 Extended emission size (y-axis) (3)
30 I1 --- RCpeaks [1/5] Number of radio continuum (RC) peaks
32- 34 A3 --- MorphType Morphological type according to
Wood & Churchwell (1989ApJS...69..831W 1989ApJS...69..831W) (4)
36 A1 --- Ch06/07 [YN] Presence of Bubble-like structures from
IRAC images according to Churchwell et al.
(2006ApJ...649..759C 2006ApJ...649..759C, Cat. J/ApJ/649/759;
2007ApJ...670..428C 2007ApJ...670..428C, Cat. J/ApJ/670/428)
38 A1 --- Simp12 [YN] Presence of Bubble-like structures from
IRAC and MIPS images according to
Simpson et al. (2012MNRAS.424.2442S 2012MNRAS.424.2442S,
Cat. J/MNRAS/424/2442)
40 A1 --- Bubble [YPN] Presence of Bubble-like structures
according to this work
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Note (1): Flag as follows:
Y = yes
N = no
P = possible
U = unlikely
Note (2): References as follows:
1 = Koo et al. (1996ApJ...456..662K 1996ApJ...456..662K)
2 = Kurtz et al. (1999ApJ...514..232K 1999ApJ...514..232K)
3 = Kim & Koo (2001ApJ...549..979K 2001ApJ...549..979K)
Note (3): EE size was obtained fitting a box to the contour of lower value on
3.6cm maps
Note (4): Morphological type as follows:
I = spherical (or unresolved)
II = cometary (parabolic)
III = core halo
IV = shell
V = irregular (or multiply peaked)
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Name Name of the HII region (GLLL.ll+BB.bb)
14 A1 --- f_Name [cd] Flag on Name (1)
16- 26 A11 --- OName IRAS name of the HII region (HHMMm+DDMMA)
28- 29 I2 h RAh Right ascension (J2000)
31- 32 I2 min RAm Right ascension (J2000)
34- 37 F4.1 s RAs Right ascension (J2000)
39 A1 --- DE- Declination sign (J2000)
40- 41 I2 deg DEd Declination (J2000)
43- 44 I2 arcmin DEm Declination (J2000)
46- 49 F4.1 arcsec DEs Declination (J2000)
51- 54 F4.1 kpc Dist Distance
56 I1 --- r_Dist [1/5] Reference for Dist (2)
58- 60 F3.1 arcmin Size1 Size (x-axis)
62- 64 F3.1 arcmin Size2 Size (y-axis)
66 A1 --- Bubble [YP] Presence of Bubble-like structures (3)
68 I1 --- RCpeaks [1/5] Number of radio continuum (RC) peaks
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Note (1): Flag as follows:
c = This source was studied in detail and confirmed to host a hot core by
de la Fuente et al. (2018RMxAA..54..129D 2018RMxAA..54..129D)
d = The source G60.87-0.11, located ∼1.5arcmin to the West of this source,
is proposed as a new UC HII+EE, but more data are needed to confirm this
Note (2): References as follows:
1 = Wood & Churchwell (1989ApJS...69..831W 1989ApJS...69..831W)
2 = Churchwell et al. (1990A&AS...83..119C 1990A&AS...83..119C)
3 = Kurtz et al. (1994ApJS...91..659K 1994ApJS...91..659K, Cat. J/ApJS/91/659)
4 = Araya et al. (2002ApJS..138...63A 2002ApJS..138...63A, Cat. J/ApJS/138/63)
5 = Kurtz et al. (1999ApJ...514..232K 1999ApJ...514..232K)
Note (3): In this work, Y = Yes and P = Probably, based on the availability of
Spitzer data. However, for those marked with P and without MIPS data,
the 2MASS Ks image suggests that gas emission matches the morphology
of RC data (see Fig. 4 of the article).
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Name of the HII region (GLLL.ll+BB.bb)
14- 17 F4.1 10+4Lsun LIRAS Total luminosity measured via IRAS fluxes
19- 23 F5.2 [s-1] logN*c Logarithm of the ionizing photon rate
N*c (G2)
25- 28 A4 --- SpTypeI Spectral type from IRAS observations
30 A1 --- VLA [CD] VLA configuration
32- 36 F5.2 [s-1] logN**c Logarithm of the ionizing photon rate
N**c (G3)
38- 41 A4 --- SpTyper Spectral type from radio observations
43- 46 F4.2 --- fd(CD) Fraction of UV photons absorbed by dust
and hence without causing ionization for
VLA C or D configuration
48- 51 F4.2 --- fd(B) ? Fraction of UV photons absorbed by dust
and hence without causing ionization for
VLA B configuration
53 I1 --- r_fd(B) [1/2]? Reference for fd(B) (G4)
55 I1 --- EElev [1/3]? Different levels at which EE
reduces the values of fd explaining the
IR excess (1)
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Note (1): EElev as follows:
1 = Low
2 = Intermediate
3 = High
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Name Name of the HII region (GLLL.ll+BB.bb)
14- 17 F4.1 10+4Lsun LIRAS Total luminosity measured via IRAS fluxes
19- 23 F5.2 [s-1] logN*c Logarithm of the ionizing photon rate
N*c (G2)
25- 28 A4 --- SpTypeI Spectral type from IRAS observations
30 A1 --- VLA [CD] VLA configuration
32- 36 F5.2 [s-1] logN**c Logarithm of the ionizing photon rate
N**c (G3)
38- 41 A4 --- SpTyper Spectral type from radio observations
43- 46 F4.2 --- fd(B) ? Fraction of UV photons absorbed by dust
and hence without causing ionization for
VLA B configuration
48 I1 --- r_fd(B) [1/2]? Reference for fd(B) (G4)
50- 53 F4.2 --- fd(CD) Fraction of UV photons absorbed by dust
and hence without causing ionization for
VLA C or D configuration
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Global Notes:
Note (G1): Flag as follows:
c = These sources were previously catalogued as UC HII regions (Kim & Koo
2001ApJ...549..979K 2001ApJ...549..979K), but other peaks in our RC images seem to be
associated with the EE: G23.44-0.21 instead of G23.46-0.20, and
G25.69+0.03 instead of G25.72+0.05. See Section 4.2 for details.
Note (G2): The ionizing photon rate N*c is converted from the total
luminosity measured via IRAS fluxes, using model stellar atmospheres
(Panagia 1973AJ.....78..929P 1973AJ.....78..929P; Casoli et al. 1986A&A...169..281C 1986A&A...169..281C;
Wood & Churchwell 1989ApJS...69..831W 1989ApJS...69..831W; Kurtz et al.
1994ApJS...91..659K 1994ApJS...91..659K, Cat. J/ApJS/91/659)
Note (G3): The ionizing photon rate, N**c, is estimated from the 3.6cm
observations in the D configuration using equation (1) of
Kurtz et al. (1994ApJS...91..659K 1994ApJS...91..659K, Cat. J/ApJS/91/659)
Note (G4): References as follows:
1 = Wood & Churchwell (1989ApJS...69..831W 1989ApJS...69..831W)
2 = Kurtz et al. (1994ApJS...91..659K 1994ApJS...91..659K, Cat. J/ApJS/91/659)
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