SIMBAD references

2002ApJ...567..980G - Astrophys. J., 567, 980-998 (2002/March-2)

Methanol and silicon monoxide observations toward bipolar outflows associated with class 0 objects.


Abstract (from CDS):

We report Swedish-ESO Submillimetre Telescope observations of seven bipolar outflows thought to be associated with Class 0 objects in the υ=0J=3⟶2 and J=2⟶1 transitions of SiO and Jk=3k⟶2k and Jk=2k⟶1k transitions of CH3OH. Methanol and silicon monoxide emission from outflowing gas were detected toward the lobes of four objects (NGC 2264G, IRAS 16293-2422, Serpens S68N, and Serpens SMM 4). The SiO line profiles are characteristics of C-type bow shocks, showing a peak at a radial velocity close to but displaced from the ambient cloud velocity and a gradual decrease in intensity from the peak toward higher flow velocities. There is a significant correlation between the column density of SiO and the terminal SiO flow velocity, which suggests a velocity-selective enhancement in the production of SiO molecules. We find that the SiO abundance in the lobes is enhanced with respect to that of the ambient cloud by a factor of at least 330 in IRAS 16293-2422 and SMM 4, 170 in NGC 2264G, and 80 in S68N. The CH3OH abundance is enhanced by a factor of 500 in IRAS 16293-2422, 330 in SMM 4, 80 in S68N, and 23 in NGC 2264G. In addition, we find that the dependence of the SiO/CO and CH3OH/CO abundance ratios with radial flow velocity shows a steep increase in the range from ∼0 to ∼4-5 km.s–1 and a gradual decline toward higher flow velocities. In the remaining three sources (CG 30, IRAS 13036-7644, and VLA 1623-243), emission in methanol was detected from a narrow line at the velocity of the ambient cloud, and no emission was detected in silicon monoxide. Weak methanol emission from a low-velocity outflow component was detected toward CG 30.

Abstract Copyright:

Journal keyword(s): ISM: Abundances - ISM: individual (IRAS 16293-2422, NGC 2264G, Serpens) - ISM: Jets and Outflows - ISM: Molecules - Stars: Formation

Simbad objects: 30

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