J/A+A/616/A107 (Sub)millimeter RRL in high-mass star-forming clumps (Kim+, 2018)
New detections of (sub)millimeter hydrogen radio recombination lines
towards high-mass star-forming clumps.
Kim W.-J., Urquhart J.S., Wyrowski F., Menten K.M., Csengeri T.
<Astron. Astrophys. 616, A107 (2018)>
=2018A&A...616A.107K 2018A&A...616A.107K (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; H II regions ; Millimetric/submm sources ;
Interstellar medium ; Star Forming Region
Keywords: surveys - stars: massive - stars: formation - H II regions -
submillimeter: ISM
Abstract:
Previous radio recombination line (RRL) observations of dust clumps
identified in the APEX Telescope Large Area Survey of the Galaxy
(ATLASGAL) have led to the detection of a large number of RRLs in the
3mm range. Here, we aim to study their excitation with shorter
wavelength (sub)millimeter radio recombination line (submm-RRL)
observations. We made observations of submm-RRLs with low principal
quantum numbers (n≤30) using the APEX 12m telescope, toward 104 HII
regions associated with massive dust clumps from ATLASGAL. The
observations covered the H25α, H28α, and H35β
transitions. Toward a small subsample the H26α, H27α,
H29α, and H30α lines were observed to avoid contamination
by molecular lines at adjacent frequencies. We have detected
submm-RRLs (signal-to-noise ≥3σ) from compact HII regions
embedded within 93 clumps. The submm-RRLs are approximately a factor
of two brighter than the mm-RRLs and consistent with optically thin
emission in local thermodynamic equilibrium (LTE). The average ratio
(0.31) of the measured H35β/H28α fluxes is close to the LTE
value of 0.28. No indication of RRL maser emission has been found. The
Lyman photon flux, bolometric, and submm-RRL luminosities toward the
submm-RRL detected sources present significant correlations. The
trends of dust temperature and the ratio of bolometric luminosity to
clump mass, Lbol/Mclump, indicate that the HII regions are related
to Lbol/Mclump, indicate that the HII regions are related to the
most massive and luminous clumps. By estimating the production rate of
ionizing photons, Q, from the submm-RRL flux, we find that the
Q(H28α) measurements provide estimates of the Lyman continuum
photon flux consistent with those determined from 5GHz radio continuum
emission. Six RRL sources show line profiles that are a combination of
a narrow and a broad Gaussian feature. The broad features are likely
associated with high-velocity ionized flows. We have detected
submm-RRLs toward 93 ATLASGAL clumps. Six RRL sources have
high-velocity RRL components likely driven by high-velocity ionized
flows. Their observed properties are consistent with thermal emission
that correlates well with the Lyman continuum flux of the HII regions.
The sample of HII regions with mm/submm-RRL detections probes, in our
Galaxy, luminous clumps (Lbol>104L☉) with high
Lbol/Mclump. We also provide suitable candidates for further
studies of the morphology and kinematics of embedded, compact HII
regions with the Atacama Large Millimeter/submillimeter Array (ALMA).
Description:
Gaussian fit parameters of submillimeter hydrogen recombination lines
toward 93 dust clumps and properties of dust clumps and embedded
central stars are provided.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 66 333 Line parameters of all hydrogen RRLs
table6.dat 85 104 Properties of clumps and embedded sources
fig2sp/* . 93 Individual submm RRL spectrum image
fits/* . 11 Transition repertories with fits spectra
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See also:
J/MNRAS/473/1059 : Complete sample of Galactic clump properties
(Urquhart+, 2018)
J/A+A/602/A37 : Millimeter RRL in ATLASGAL-selected massive clumps
(Kim+, 2017)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID [1/104] ID of ATLASGAL clump
5- 22 A18 --- Name ATLASGAL clump name (AGALLLL.lll+BB.bbb)
24- 34 A11 --- Trans RRL transitions
35- 37 I3 km/s RRLVlsr LSR velocity of RRLs
39- 40 I2 km/s dv RRL linewidth
42- 43 I2 km/s e_dv rms uncertainty on dv
45- 50 F6.1 Jy.km/s Fint RRL velocity-integrated flux on Jy scale
52- 55 F4.1 Jy.km/s e_Fint rms uncertainty on velocity-integrated flux
57- 61 F5.2 Jy Fpeak RRL peak intensity on Jy scale
63- 66 F4.2 Jy rms rms noise per channel
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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- 3 I3 --- ID [1/104] ID of ATLASGAL clump
5- 22 A18 --- Name ATLASGAL clump name (AGALLLL.lll+BB.bbb)
24- 28 F5.1 km/s sysVlsr LSR systemic velocity of clumps
30- 34 F5.1 km/s RRLVlsr LSR velocity of recombination line
36- 39 F4.1 kpc Dist ?=- Heliocentric distance
41- 44 F4.1 K Tdust ?=- Dust temperature
46- 48 F3.1 [Lsun] logLbol ?=- Log of bolometric luminosity
50- 52 F3.1 [Msun] logMclump ?=- Log of the clump mass
54- 56 F3.1 --- logL/M ?=- Log of ratio of Lbol and Mclump
58- 61 F4.1 [ph/s] logLyman ?=- Lyman photon flux of radio continuum
63 I1 --- Fig2 [2]? indicates an image of all spectra
65 A1 --- H25a [*] indicates a h25alpha spectrum
67 A1 --- H26a [*] indicates a h26alpha spectrum
69 A1 --- H27a [*] indicates a h27alpha spectrum
71 A1 --- H28a [*] indicates a h28alpha spectrum
73 A1 --- H29a [*] indicates a h29alpha spectrum
75 A1 --- H30a [*] indicates a h30alpha spectrum
77 A1 --- H35b [*] indicates a h35beta spectrum
79 A1 --- H39a [*] indicates a h39alpha spectrum
81 A1 --- H40a [*] indicates a h40alpha spectrum
83 A1 --- H41a [*] indicates a h41alpha spectrum
85 A1 --- H42a [*] indicates a h42alpha spectrum
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Acknowledgements:
Won-Ju Kim, wjkim(at)mpifr-bonn.mpg.de, kim(at)iram.es
(End) Won-Ju Kim [IRAM, Spain], Patricia Vannier [CDS] 10-May-2018