J/A+A/609/A16 OMC 1 reduced H2CO(3-2) datacubes (Tang+, 2018)
Kinetic temperature of massive star-forming molecular clumps measured with
formaldehyde.
III. The Orion Molecular Cloud 1.
Tang X.D., Henkel C., Menten K.M., Wyrowski F., Brinkmann N., Zheng X.W.,
Gong Y., Lin Y.X., Esimbek J., Zhou J.J., Yuan Y., Li D.L., He Y.X.
<Astron. Astrophys. 609, A16 (2018)>
=2018A&A...609A..16T 2018A&A...609A..16T (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Radio lines
Keywords: stars: formation - stars: massive - ISM: clouds - ISM: molecules -
radio lines: ISM
Abstract:
We mapped the kinetic temperature structure of the Orion molecular
cloud 1 (OMC-1) with para-H2CO(JKaKc=303-202, 322-221, and
321-220) using the APEX 12m telescope. This is compared with the
temperatures derived from the ratio of the NH3 (2,2)/(1,1) inversion
lines and the dust emission. Using the RADEX non-LTE model, we derive
the gas kinetic temperature modeling the measured averaged line ratios
of para-H2CO 322-221/303-202 and
321-220/303-202. The gas kinetic temperatures derived from
the para-H2CO line ratios are warm, ranging from 30 to >200K with an
average of 62±2K at a spatial density of 105cm-3. These
temperatures are higher than those obtained from NH3 (2,2)/(1,1) and
CH3CCH(6-5) in the OMC-1 region. The gas kinetic temperatures
derived from para-H2CO agree with those obtained from warm dust
components measured in the mid infrared (MIR), which indicates that
the para-H2CO(3-2) ratios trace dense and warm gas. The cold dust
components measured in the far infrared (FIR) are consistent with
those measured with NH3 (2,2)/(1,1) and the CH3CCH(6-5) line
series. With dust at MIR wavelengths and para-H2CO(3-2) on one side
and dust at FIR wavelengths, NH3 (2,2)/(1,1), and CH3CCH(6-5) on
the other, dust and gas temperatures appear to be equivalent in the
dense gas (n(H2)≳104cm-3) of the OMC-1 region, but provide a
bimodal distribution, one more directly related to star formation than
the other. The non-thermal velocity dispersions of para-H2CO are
positively correlated with the gas kinetic temperatures in regions of
strong non-thermal motion (Mach number ≳2.5) of the OMC-1, implying
that the higher temperature traced by para-H2CO is related to
turbulence on a ∼0.06pc scale. Combining the temperature measurements
with para-H2CO and NH3 (2,2)/(1,1) line ratios, we find direct
evidence for the dense gas along the northern part of the OMC-1 10km/s
filament heated by radiation from the central Orion nebula.
Description:
Reduced H2CO(3-2) datacubes (brightness unity in Ta* (K)).
Objects:
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RA (2000) DE Designation(s)
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05 35 14 -05 22.4 Orion Molecular Cloud 1 = OMC 1
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 117 3 List of fits datacubes
fits/* . 3 Individual datacubes
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See also:
J/A+A/598/A30 : Massive star forming molecular clumps Tkin (Tang+, 2017)
J/A+A/600/A16 : Six LMC star forming region spectra (Tang+, 2017)
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- 21 I2 --- Nx Number of pixels along X-axis
23- 24 I2 --- Ny Number of pixels along Y-axis
26- 27 I2 --- Nz Number of slices
29- 37 F9.2 m/s bVrad Lower value of radial velocity interval
39- 45 F7.1 m/s BVrad Upper value of radial velocity interval
47- 53 F7.3 m/s dVrad Radial velocity resolution
55- 58 I4 Kibyte size Size of FITS file
60- 76 A17 --- FileName Name of FITS file, in subdirectory fits
78-117 A40 --- Title Title of the FITS file
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Acknowledgements:
Xindi Tang, xdtang(at)mpifr-bonn.mpg.de
References:
Tang et al., Paper I 2017A&A...598A..30T 2017A&A...598A..30T, Cat. J/A+A/598/A30
Tang et al., Paper II 2017A&A...600A..16T 2017A&A...600A..16T, Cat. J/A+A/600/A16
(End) Patricia Vannier [CDS] 22-Sep-2017