J/A+A/589/A44 W51 Main NH3 and CH3OH data cubes (Goddi+, 2016)
Hot ammonia around young O-type stars
III. High-mass star formation and hot core activity in W51 Main.
Goddi C., Ginsburg A., Zhang Q.
<Astron. Astrophys. 589, A44 (2016)>
=2016A&A...589A..44G 2016A&A...589A..44G (SIMBAD/NED BibCode)
ADC_Keywords: H II regions ; Interstellar medium
Keywords: accretion, accretion disks - line: profiles -
ISM: kinematics and dynamics - ISM: molecules - stars: protostars -
HII regions
Abstract:
This paper is the third in a series of NH3 multilevel imaging
studies in well-known, high-mass star-forming regions. The main goal
is to characterize kinematics and physical conditions of (hot and
dense) circumstellar molecular gas around O-type young stars.
We want to map at subarcsecond resolution highly excited inversion
lines of NH3 in the high-mass star-forming region W51 Main
(distance = 5.4kpc), which is an ideal target to constrain
theoretical models of high-mass star formation.
Using the Karl Jansky Very Large Array (JVLA), we mapped the hot and
dense molecular gas in W51 Main with ∼0.2"-0.3" angular resolution in
five metastable (J = K) inversion transitions of ammonia (NH3):
(J,K) = (6, 6), (7, 7), (9, 9), (10, 10), and (13, 13). These
lines arise from energy levels between ∼400K and ∼1700K above the
ground state. We also made maps of the (free-free) continuum emission
at frequencies between 25 and 36GHz.
Description:
Observations of NH3 toward the W51 complex were conducted using the
Karl G. Jansky Very Large Array (JVLA) of the National Radio Astronomy
Observatory (NRAO)1 in the B configuration.
By using the broadband JVLA K- and Ka-band receivers, we observed a
total of five metastable inversion transitions of NH3: (J,K) = (6, 6),
(7, 7), (9, 9), (10, 10), and (13, 13) at the 1cm band with
frequencies ranging from ∼25GHz for the (6, 6) line to ∼33GHz
for the (13, 13) line. Transitions were observed in pairs of
independently tunable basebands during 6h tracks (two targets per
track: W51 - this paper; NGC 7538 IRS1 - Paper I, Goddi et al.,
2015A&A...573A.108G 2015A&A...573A.108G) on three different dates in 2012: the (6, 6) and
(7, 7) lines on May 31 at K-band, the (9, 9) and (13, 13) lines on
June 21, and the (10, 10) transition on August 7, both at Ka-band.
Each baseband had eight sub-bands with a 4MHz bandwidth (∼40km/s at
30GHz), providing a total coverage of 32MHz (∼320km/s at 30GHz). Each
sub-band consisted of 128 channels with a separation of 31.25kHz
(∼0.3km/s at 30GHz). The typical on-source integration time was about
80min. Each transition was observed with fast switching, where 80s
scans on target were alternated with 40s scans on the nearby (1.2°
on the sky) QSO J1924+1540 (measured flux density 0.6-0.7Jy, depending
on frequency). We derived absolute flux calibration from observations
of 3C 48 (Sν=0.5-0.7Jy, depending on frequency), and bandpass
calibration from observations of 3C 84 (Sν=27-29Jy, depending on
frequency).
Objects:
---------------------------------------------
RA (2000) DE Designation(s)
---------------------------------------------
19 23 43.90 +14 30 34.8 W51e2 = W 51E2
---------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 186 6 List of fits datacubes
fits/* . 6 Individual fits datacubes
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See also:
J/ApJS/191/232 : CO survey of W51 molecular cloud (Bieging+, 2010)
J/ApJ/720/1055 : VBLA observations of W51 Main/South (Sato+, 2010)
J/A+A/582/A64 : W51/e2 and G34.3+0.2 IRAM spectra (Lykke+, 2015)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 30 I3 --- Nz Number of slices
32- 52 A21 --- Obs.Date Observation date
54- 65 E12.6 Hz bFreq Lower value of frequency interval
67- 78 E12.6 Hz BFreq Upper value of frequency interval
79- 85 F7.1 Hz dFreq Frequency resolution
87- 92 I6 Kibyte size Size of FITS file
94-126 A33 --- FileName Name of FITS file, in subdirectory fits
128-186 A59 --- Title Title of the FITS file
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Acknowledgements:
Ciriaco Goddi, C.Goddi(at)astro.ru.nl
References:
Goddi et al., Paper I 2015A&A...573A.108G 2015A&A...573A.108G
Goddi et al., Paper II 2015A&A...573A.109G 2015A&A...573A.109G
(End) Patricia Vannier [CDS] 25-Apr-2016