Visit ASIAA Homepage Registration Deadline: August 15, 2019 (Taiwan Time)
Science with the Submillimeter Array: Present and Future
November 4(Mon)-5(Tue), 2019
ASIAA, Taipei, Taiwan

Poster Presentation

Probing the Chemistry of Low Mass - and High Mass Star Forming Regions using the Submillimeter Array

Author(s): Ivalu Christensen(Lund University, Sweden), Nimesh Patel(Center for Astrophysics | Harvard & Smithsonian (USA), Andrew Burkhardt (Center for Astrophysics | Harvard & Smithsonian (USA)

Presenter: Nimesh Patel (Center for Astrophysics | Harvard & Smithsonian)

The physical processes leading to the formation of high-mass stars remain poorly understood compared to low-mass stars. Astrochemistry can provide important clues, since observations of molecular lines can be used as probes of physical conditions, and many molecular lines are important coolants in the gas in star-forming regions. We study the chemistry of high mass star forming regions (SFR) G35.2-0.7N (G35.2N) and low mass SFR IRAS 16293-2422 (I16293), where previous studies show multiple condensations in both. We used Submillimeter Array archival data to analyze the continuum and line emission in both sources. I16293 is well known to have two components, where both are observed with our beam size of 1”. Continuum emission of G35.2N reveals three cores, with our beam size of 3”. We identified 33 species in the lines observed in the I16293, 17 in G35.2-0.7N. Our study allows a comparison of the chemistry between low and high-mass SFRs, with I16293 representing a typical low-mass hot corino and G35.2N, high-mass hot cores. We find 7 molecules in common - CO isotopologues, SO, CH$_3$CN, CH$_3$OH and HNCO. Although G35.2N appears to be not as rich in lines, complex organic molecules are observed in one of its cores. LTE column densities and excitation temperatures are determined for CH$_3$CN, HNCO, C2H5OH, CH$_3$OCHO and $^{13}$C isotopologues of some of these species, which show G35.2N core A and I16293 have comparable column densities. However, the excitation temperatures are lower for the high mass SFR. We also present results on fractionation of [X-CHO]/[X-CH$_3$]. Previous studies have observed the latter ratio as an identifier of high-mass SFR. The fraction in I16293 of [CH$_3$OCHO]/[CH$_3$OCH$_3$] is 0.89 and 0.66 for cores A and B, respectively, while for G35.2N core A, it is 0.26. From the dust continuum emission, we derive masses of 0.2 and 0.1 $_{\odot}$ for I16293 corino A and B, respectively and for G35.2N cores A and B, 20.4 and 145.4 M$_{\odot}$, respectively. Finally, the detection of various molecular species in all sources are compared using Venn diagrams.

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