Shock Chemistry in Bipolar Molecular Outflows

Bachiller, R.; Gutiérrez, Manuel Pérez

doi:10.1017/s0074180900061623

Cited by 2 publications

(1 citation statement)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Second, at this position we found some heating and the NH 3 /N 2 H + abundance ratio shows lower values than those in the southern part of BIMA 4 (Fig. 10a,d; temperature enhancement and chemical variations are signatures of shocked molecular gas, e. g., L1157 : Bachiller & Pérez Gutiérrez 1997). Third, the N 2 H + line broadening along outflow B (which is also observed in NH 3 ) indicates that the outflow is already interacting with the molecular cloud (Fig.…”

Section: Outflow Bmentioning

confidence: 67%

Star formation in a clustered environment around the UCH ${\mathsf{II}}$ region in IRAS 20293+3952

Palau¹,

Estalella²,

Girart

et al. 2007

A&A

View full text Add to dashboard Cite

Aims. We aim at studying the cluster environment surrounding the UCH ii region in IRAS 20293+3952, a region in the first stages of formation of a cluster around a high-mass star. Methods. BIMA and VLA were used to observe the 3 mm continuum, N 2 H + (1-0), NH 3 (1, 1), NH 3 (2, 2), and CH 3 OH (2-1) emission of the surroundings of the UCH ii region. We studied the kinematics of the region and computed the rotational temperature and column density maps by fitting the hyperfine structure of N 2 H + and NH 3 . Results. The dense gas traced by N 2 H + and NH 3 shows two different clouds, a main cloud to the east of the UCH ii region, of ∼0.5 pc and ∼250 M , and a western cloud, of ∼0.15 pc and ∼30 M . The dust emission reveals two strong components in the northern side of the main cloud, BIMA 1 and BIMA 2, associated with Young Stellar Objects (YSOs) driving molecular outflows, and two fainter components in the southern side, BIMA 3 and BIMA 4, with no signs of star forming activity. Regarding the CH 3 OH, we found strong emission in a fork-like structure associated with outflow B, as well as emission associated with outflow A. The YSOs associated with the dense gas seem to have a diversity of age and properties. The rotational temperature is higher in the northern side of the main cloud, around 22 K, where there are most of the YSOs, than in the southern side, around 16 K. There is strong chemical differentiation in the region, since we determined low values of the NH 3 /N 2 H + ratio, ∼50, associated with YSOs in the north of the main cloud, and high values, up to 300, associated with cores with no detected YSOs, in the south of the main cloud. Such a chemical differentiation is likely due to abundance/depletion effects. Finally, interaction between the different sources in the region is important. First, the UCH ii region is interacting with the main cloud, heating it and enhancing the CN (1-0) emission. Second, outflow A seems to be excavating a cavity and heating its walls. Third, outflow B is interacting with the BIMA 4 core, likely producing the deflection of the outflow and illuminating a clump located ∼0.2 pc to the northeast of the shock. Conclusions. The star formation process in IRAS 20293+3952 is not obviously associated with interactions, but seems to take place where density is highest.

show abstract

Section: Outflow Bmentioning

confidence: 67%

Star formation in a clustered environment around the UCH ${\mathsf{II}}$ region in IRAS 20293+3952

Palau¹,

Estalella²,

Girart

et al. 2007

A&A

View full text Add to dashboard Cite

show abstract

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

Villarmois

Kristensen

Jørgensen

2019

A&A

View full text Add to dashboard Cite

Context. Recent results suggest that the first steps towards planet formation may be already taking place in protoplanetary discs during the first 100,000 years 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 (150-300 AU) scales. The wide instantaneous band-width of the SMA observations (∼30 GHz) 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 H 2 CO 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.

show abstract

Shock Chemistry in Bipolar Molecular Outflows

Cited by 2 publications

References 18 publications

Star formation in a clustered environment around the UCH ${\mathsf{II}}$ region in IRAS 20293+3952

Star formation in a clustered environment around the UCH ${\mathsf{II}}$ region in IRAS 20293+3952

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

Contact Info

Product

Resources

About