J/A+A/631/A137 IRAS 16293-2422 CH3CCH spectral cubes (Calcutt+, 2019)
The ALMA-PILS survey: propyne (CH3CCH) in IRAS 16293-2422.
Calcutt H., Willis E.R., Jorgensen J.K., Bjerkeli P., Ligterink N.F.W.,
Coutens A., Muller H.S.P., Garrod R.T., Wampfler S.F., Drozdovskaya M.N.
<Astron. Astrophys. 631, A137 (2019)>
=2019A&A...631A.137C 2019A&A...631A.137C (SIMBAD/NED BibCode)
ADC_Keywords: Infrared sources ; Interstellar medium ; Spectroscopy
Keywords: astrochemistry - stars: formation - stars: protostars -
ISM: molecules - ISM: individual objects: IRAS 16293-2422
Abstract:
Propyne (CH3CCH) has been detected in a variety of environments,
from Galactic star-forming regions to extragalactic sources. Such
molecules are excellent tracers of the physical conditions in
star-forming regions.
This study explores the emission of CH3CCH in the low-mass
protostellar binary, IRAS 16293-2422, examining the spatial scales
traced by this molecule, as well as its formation and destruction
pathways.
ALMA observations from the Protostellar Interferometric Line Survey
(PILS) are used to determine the abundances and excitation
temperatures of CH3CCH towards both protostars, exploring spatial
scales from 70 to 2400au. The three-phase chemical kinetics model
MAGICKAL is also used, to explore the chemical reactions of this
molecule.
CH3CCH is detected towards both IRAS 16293A and IRAS 16293B and is
found to trace the hot corino component around each source in the PILS
dataset. Eighteen transitions above 3σ are detected, enabling
robust excitation temperatures and column densities to be determined
in each source. In IRAS 16293A, an excitation temperature of 90K and a
column density of 7.8x1015cm-2 best fits the spectra. In IRAS
16293B, an excitation temperature of 100K and 6.8x1015cm-2 best
fits the spectra. The chemical modelling finds that in order to
reproduce the observed abundances, both gas-phase and grain-surface
reactions are needed.
CH3CCH is a molecule whose brightness and abundance in many
different regions can be utilised to provide a benchmark of molecular
variation with the physical properties of star-forming regions. It is
essential when making such comparisons, that the abundances are
determined with a good understanding of the spatial scale of the
emitting region, to ensure that accurate abundances are derived
Description:
This data collection contains 15 spectral cubes (RA, Dec, Frequency)
extracted from the ALMA-PILS dataset. Additional reduction and
processing issues are given in Jorgensen et al. (2016A&A...595A.117J 2016A&A...595A.117J).
Each FITS file represents a small frequency range around the CH3CCH
lines discussed in the paper.
Objects:
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RA (2000) DE Designation(s)
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16 32 22.56 -24 28 31.8 IRAS 16293-2422 = JCMTSF J163222.8-242837
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 166 15 List of spectral cubes
fits/* . 15 Individual spectral cubes
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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- 29 I2 --- Nz Number of pixels along Z-axis
31- 56 A26 "datime" Obs.Date Observaiton date
58- 64 F7.3 GHz bFreq Lower value of frequency interval
66- 72 F7.3 GHz BFreq Upper value of frequency interval
74- 81 F8.1 Hz dFreq Frequency resolution
83- 86 I4 Kibyte size Size of FITS file
88-117 A30 --- FileName Name of FITS file, in subdirectory fits
119-166 A48 --- Title Title of the FITS file
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Acknowledgements:
Hannah Calcutt, hannah.calcutt(at)chalmers.se
(End) Patricia Vannier [CDS] 16-Oct-2019