Shining a Light on the Kinematics and Chemical Complexity of Massive Protostars
Abstract
Massive protostars are powerful sources of radiative and mechanical feedback that regulate star-forming clouds. They are also stellar laboratories with which to study astrochemical processes within these molecular clouds. Analysis of their spectra yields important clues for the formation of many organic molecules. Using archival ALMA Band 7 data, this project characterizes the spectra of four massive protostars from the SOFIA Massive (SOMA) Star Formation Survey, and one additional protostar. We analyzed 7m-array spectra with CASA and identified and fit lines with CASSIS. Seven other SOMA protostars previously studied with ALMA Band 6 data by our group were added to increase the sample. To describe the chemical complexity of each source, we define a spectral line density metric based on the average number of lines per GHz. The sources have a wide range of spectral line densities from ~1 per GHz in G351.47 to >60 per GHz in G337.41. For this source, we also analyzed high resolution moment maps of molecular emission from ALMA 12m-array data. For sources with multiple transitions of key molecules, such as CH3OH, SO2 and CH3OCHO, we derive gas temperatures and column densities from rotational diagrams. From infrared spectral energy distribution (SED) fitting, we derive luminosities, core envelope masses, protostellar masses and clump mass surface densities of the sources and evaluate correlations of these properties with chemical complexity. Line parameters FWHM and integrated intensity of three common species, CH3OH, SO in Band 7 and H2S in Band 6, are also compared against the SED-derived protostellar properties. Overall, these results help to define the chemical and dynamical evolutionary sequences of massive protostars and provide important observational constraints with which to test theoretical models.
- Publication:
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American Astronomical Society Meeting Abstracts
- Pub Date:
- January 2023
- Bibcode:
- 2023AAS...24130806L