4-8 October 2015
Hans Harnack Haus
Europe/Berlin timezone
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Contribution Poster

Poster session

A 3mm line survey of Barnard 1b: looking into the chemical content of a protostellar system

Speakers

  • Dr. Nuria MARCELINO

Primary authors

Co-authors

Content

The Barnard 1 cloud is one of the highest column density regions in the Perseus molecular complex, which comprises several dense cores at different evolutionary stages of star formation. Of those, B1b has been recently found to contain two very young protostellar objects, B1b-N and B1b-S, separated by 20''. IRAM PdBI observations show the presence of slow molecular outflows arising from each core, whose obtained parameters are consistent with B1b-N being a First Hydrostatic Core candidate and B1b-S a very young Class 0 object. Nevertheless, the sources are deeply embedded in a high density ($\sim10^5$ cm$^{-3}$) and low kinetic temperature ($\sim$12 K) protostellar envelope.

We present the results of a spectral line survey towards the B1b system, covering the whole 3 mm band at the IRAM 30m telescope (82.5-117.5 GHz). These broad-band unbiased studies provide a complete view of the molecular complexity and the opportunity to detect new species, which are challenging the current chemical models in pre/proto-stellar cores. So far we have detected 426 lines from 107 molecular species and isotopologues, for which we have obtained column densities and abundances. More than 100 lines remain unidentified. Our results show a rich and complex spectra, in particular of deuterated species and complex organics --some of them detected for the first time in cold pre/proto-stellar cores (e.g. CH$_3$O, CH$_3$OCHO and CH$_3$OCH$_3$). This peculiar chemistry should be related to the physical state of the B1b-N and b-S cores towards the formation of a protostar. We have also detected a large number of molecular ions and derived the local value of the cosmic ionization rate. This is a key parameter to determine the evolution of the gas during the earliest phases of star formation.