Molecules with ALMA at Planet Forming Scales

Molecules with ALMA at Planet Forming Scales

Planets form and obtain their compositions in disks around young stars, and the outcome of this process is intimately linked to the disk chemistry and structure.

‘Molecules with ALMA at Planet-forming Scales’ (MAPS) is an ALMA Large Program (2018.1.01055.L) designed to expand our understanding of the chemistry of planet formation by exploring protoplanetary disk chemical structures down to 10 au scales.

Together these observations provide constraints on a range of disk properties related to planet formation. In particular, MAPS was designed to answer the following key questions…

  • How are dust and chemical substructures linked?
  • Where do molecules reside vertically in the disks?
  • What are the main organic reservoirs, C/N/O/S, and D/H ratios in the planet-forming disk regions?
  • How can we probe ionization and dynamic disk processes?

You can find out more about the MAPS results at the dedicated project website.

MAPS IX: The distribution and properties of large organic molecules

Within MAPS, I led the analysis of the largest molecules observed. My paper, MAPS IX, investigates the prebiotically-interesting molecules HC3N, CH3CN, c-C3H2, which are robustly detected in all disks apart from IM Lup. We use rotation diagram analysis to infer a radially-resolved column density and rotational temperature profile for each molecule in each disk. Based on this, we find significant reservoirs of these large organics in the inner 50-100 au of the disks, emitting from very close to the midplane. Comparison of the ratio of small to large organic molecules in the disks suggests a similar composition to observations of comets. In combination, our results suggest that planets form in an environment rich with precursors of life-essential molecules, and this material has a composition similar to our own Solar System.

MAPS IX Diagram

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Dr John D. Ilee
Postdoctoral Research Fellow