J/A+A/627/A37 Class I disk Oph-IRS 67 (Artur de la Villarmois+ 2019)
Revealing the chemical structure of the Class I disk Oph-IRS 67.
Artur de la Villarmois E., Kristensen L.E., Jorgensen J.K.
<Astron. Astrophys. 627, A37 (2019)>
=2019A&A...627A..37A 2019A&A...627A..37A (SIMBAD/NED BibCode)
ADC_Keywords: YSOs ; Millimetric/submm sources
Keywords: ISM: molecules - stars: formation - protoplanetary disks -
astrochemistry - ISM: individual objects: Oph-IRS 67
Abstract:
Recent results suggest that the first steps towards planet formation
may be already taking place in protoplanetary discs during the first
100000yr after stars form. It is therefore crucial to unravel the
physical and chemical structures of such discs in their earliest
stages while they are still embedded in their natal envelopes and
compare them with more evolved systems.
The purpose of this paper is to explore the structure of a line-rich
Class I protobinary source, Oph-IRS 67, and analyse the differences
and similarities with Class 0 and Class II sources.
We present a systematic molecular line study of IRS 67 with the
Submillimeter Array (SMA) on 1-2" (150-300AU) scales. The wide
instantaneous band-width of the SMA observations (∼30GHz) provide
detections of a range of molecular transitions that trace different
physics, such as CO isotopologues, sulphur-bearing species, deuterated
species, and carbon-chain molecules.
We see significant differences between different groups of species.
For example, the CO isotopologues and sulphur-bearing species show a
rotational profile and are tracing the larger-scale circumbinary disc
structure, while CN, DCN, and carbon-chain molecules peak at the
southern edge of the disc at blue-shifted velocities. In addition, the
cold gas tracer DCO+ is seen beyond the extent of the circumbinary
disc.
The detected molecular transitions can be grouped into three main
components: cold regions far from the system, the circumbinary disc,
and a UV-irradiated region likely associated with the surface layers
of the disc that are reached by the UV radiation from the sources. The
different components are consistent with the temperature structure
derived from the ratio of two H2CO transitions, that is, warm
temperatures are seen towards the outflow direction, lukewarm
temperatures are associated with the UV-radiated region, and cold
temperatures are related with the circumbinary disc structure. The
chemistry towards IRS 67 shares similarities with both Class 0 and
Class II sources, possibly due to the high gas column density and the
strong UV radiation arising from the binary system. IRS 67 is,
therefore, highlighting the intermediate chemistry between deeply
embedded sources and T-Tauri discs.
Description:
The observations of Oph-IRS 67 were done with the Sub-Millimeter Array
(SMA) in compact and extended configurations; program code:
2016B-S0004, PI: Elizabeth Artur de la Villarmois. The calibration and
imaging were done in CASA. The extended and compact observations were
combined, appling a Briggs weighting with robustness parameter of 1.
The datacubes are 20 FITS files that correspond to 4 spectral windows
for each sideband (lower and upper) and each receiver (230 and
240GHz), plus 4 continuum images. Each spectral window has a bandwidth
of ∼2GHz.
Objects:
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RA (2000) DE Designation(s)
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16 32 01.00 -24 56 42.0 Oph-IRS 67 = WLY 2-67
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 144 20 List of fits files
fits/* . 20 Individual fits files
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
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- 32 I5 --- Nz ? Number of slices for the datacubes
34- 57 A24 "datime" Obs.date Observation date
59- 65 F7.3 GHz Freq Observed frequency or lower value of frequency
interval for datacubes
67- 73 F7.3 GHz BFreq ? Upper value of frequency interval
for datacubes
75- 80 I6 Hz dFreq ? Frequency resolution for datacubes
82- 87 I6 Kibyte size Size of FITS file
89-102 A14 --- FileName Name of FITS file, in subdirectory fits
104-144 A41 --- Title Title of the FITS file
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Acknowledgements:
Elizabeth Artur de la Villarmois, elizabeth.artur(at)nbi.ku.dk
(End) Patricia Vannier [CDS] 27-May-2019