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Deuterated Molecules in Star-Forming Regions

Kulczak-Jastrzębska M.

Acta Astronomica

2018

Vol. 68, No. 2

125--140

Imaging of the spatial distribution of deuterated molecules in several nearby low-mass star forming regions, as traced by the DCO+ (3-2) emission, suggests that the deuterated material is often displaced with respect to the highest column density regions, as traced by submillimeter dust continuum emission and sometimes appears to be associated with the high-velocity CO (2-1) emission, tracing outflow activity. High deuteration levels in isolated prestellar cores can be explained by gas-phase or grain-surface chemistry in dense, cold regions, where abundant gas-phase species are frozen onto dust grains - a process that is now relatively well understood. We argue that an alternative mechanism may operate in dense gas in the vicinity of embedded young stellar objects, where slow C-type shocks associated with molecular outflows may produce conditions favorable for deuterium fractionation either by increasing the gas volume density in the post-shock gas and thus, shortening the depletion and gas-phase reaction time-scales, or by evaporating grain mantle ices.

St 2-22 - Another Symbiotic Star with High-Velocity Bipolar Jets

Tomov T., Zamanov R., Gałan C., Pietrukowicz P.

Acta Astronomica

2017

Vol. 67, No. 3

225--242

We report the detection of high-velocity components in the wings of Hα emission line in spectra of symbiotic binary star St 2-22 obtained in 2005. This finding encouraged us to start the present investigation in order to show that this poorly-studied object is a jet-producing system. We have used high-resolution optical and low-resolution near-infrared spectra, as well as available optical and infrared photometry, to evaluate some physical parameters of the St 2-22 components and characteristics of the jets. We confirm that St 2-22 is a S-type symbiotic star. Our results demonstrate that an unnoticed outburst, similar to those in classical symbiotic systems, occurred in the first half of 2005. During the outburst, collimated bipolar jets were ejected by the hot component of St 2-22 with an average velocity of about 1700 km/s.