Query : 2019A&A...627A..37A

2019A&A...627A..37A - Astronomy and Astrophysics, volume 627A, 37-37 (2019/7-1)

Revealing the chemical structure of the Class I disc Oph-IRS 67.


Abstract (from CDS):

Context. Recent results suggest that the first steps towards planet formation may be already taking place in protoplanetary discs during the first 100 000 yr 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. Aims. 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. Methods. 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. Results. 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. Conclusions. 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.

Abstract Copyright: © ESO 2019

Journal keyword(s): ISM: molecules - stars: formation - protoplanetary disks - astrochemistry - ISM: individual objects: Oph-IRS 67

VizieR on-line data: <Available at CDS (J/A+A/627/A37): list.dat fits/*>

Simbad objects: 7

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Number of rows : 7
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 3C 273 BLL 12 29 06.6998257176 +02 03 08.597629980   13.05 14.830 14.11   ~ 5559 1
2 NVSS J162914-300003 Rad 16 29 14.9 -30 00 01           ~ 6 1
3 WLY 2-67 Y*O 16 32 00.99624 -24 56 41.9640           ~ 57 0
4 LDN 1689 DNe 16 32 22.5 -24 28 29           ~ 124 0
5 IRAS 16293-2422 cor 16 32 22.56 -24 28 31.8           ~ 1158 1
6 NAME LDN 483-mm mm 18 17 29.8 -04 39 38           ~ 21 0
7 3C 454.3 Bla 22 53 57.7480438728 +16 08 53.561508864   16.57 16.10 15.22   ~ 2664 2

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