CoCoA: Cold Cores with the Atacama Large Millimeter/submillimeter Array (ALMA)

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Understanding star formation is one of the most fundamental problems in astrophysics. Most of the stars in the Universe form in dense clusters. Low-mass stars, like our own Sun, are much more commonly formed in star clusters. High-mass stars, that are at least eight-times more massive than the Sun, on the other hand, are very rare. High mass stars live a short, but very bright, life characterized by their strong stellar winds, and sometimes a death in supernovae explosions. The investigators will test models that high-mass stars originate in "cores" where many solar masses of dense gas are concentrated into a small volume. In the investigator’s CoCoA project, they surveyed these high-mass cores with NSF’s Atacama Large Millimeter/Submillimeter Array (ALMA) observatory. The investigator will test predictions that high-mass are born in cold high-mass cores that are very turbulent. An international team of collaborators, that includes observers as well as theorists, will support this work. Custom-made numerical simulations will be used to study source properties in detail. Some of the analysis tools will be transformed into simple high-school level experiments that will be introduced to students via a local community center. The investigator seeks to introduce the scientific process to minority students.The CoCoA project has performed a systematic search for the earliest phase of high-mass star formation that builds on the ATLASGAL survey at 870 mu wavelength that covers the entire inner Galactic plane. The clumps extracted for the survey are massive, dense, and devoid of infrared sources up to 70 mu wavelengths. Using sensitive high-resolution ALMA data towards all potential candidate starless high-mass clumps within 5 kpc, CoCoA will reveal if there are any high-mass cores embedded within these clumps. The investigators will deliver information on the internal density and temperature structure of high-mass cores, and robust constraints on the lifetimes of the elusive early phase of high-mass star formation, at an unprecedented level of detail. This will involve detailed studies of the fragmentation properties of the high-mass clumps. The ALMA-based dust polarization data for a small sub-sample will tell us whether magnetic fields play any role in the early phase of high-mass star formation. In summary, the synthesis of this massive dataset will place stringent constraints on the existing theories on high-mass star formation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.