Periodic Reporting for period 1 - MOLDISK (Linking chemistry and physics in the planet-forming zones of disks)
Reporting period: 2022-01-01 to 2023-06-30
The ALMA observations focused on methanol (CH3OH), a key molecule in interstellar chemistry, as well as on more complex O- and N-containing molecules, in programs co-led by van Gelder. A surprising finding is that abundance ratios of various complex molecules are remarkably constant among dozens of sources, in spite of their very different physical conditions. This points to a common formation site, likely on ices in the cold pre-stellar phase prior to collapse of the cloud. If correct, we should then see these same molecules in the ices with future JWST observations. Also, detailed modeling was performed to explain why some protostellar systems do not show complex molecules. In particular, the presence of a disk, lowering the temperature in the immediate environment, was found to be able to "hide" emission from gaseous complex molecules by freezing them out onto grains.
JWST was launch December 25 2021, followed by commissioning (leading to an overview paper on JWST-MIRI in orbit performance) and started routine observations by mid-July 2022. The first data from our guaranteed and open time programs on protostars and disks started to arrive soon after. One early highlight, led by Leiden colleague Melissa McClure, was the observation of the "darkest" ices to date in a dense cold cloud with nearly 100 mag of extinction. It demonstrated that the ice composition is remarkably robust as function of extinction and also hinted at the presence of more complex molecules in ices. The analysis of ices and gas in protostellar systems is onging, supported by Leiden Laboratory for Astrophysics measurements: in collaboration with colleague Harold Linnartz, a database of ice spectra for use by the entire worldwide community was published and made available online by postdoc Will Rocha. Additional spectra are being measured by PhD student Katie Slavicinska. Finally, the JWST spectra of protoplanetary disks turn out to be richer than expected, with even 13C isotopologs and benzene detected for the first time in a disk, leading to several "first results" papers.