The Atacama Large Millimeter Array (ALMA) has begun operations in the high desert of northern Chile offering unprecedented spatial resolution and sensitivity within the millimeter and sub-millimeter atmospheric windows. The study of planet birth is one of the key science areas enabled by ALMA due to the ability to resolve both gas phase molecular emission within the planet formation zones of young gas-rich circumstellar disks. In this talk I will explore the related physics and chemistry of gas-rich disks and emphasize new breakthroughs in our understanding brought about by ALMA in concert with data from the Herschel Space Observatory. In particular, I will report on the physical/chemical links in terms of snow-lines and the likely formation of pebbles and possibly planetesimals. Snow-lines represent chemical transitions (ice to vapor) in the disk and have long been posited as favorable sites for planet formation. With ALMA we have now directly and indirectly resolved the carbon monoxide snow-line on the disk surface in several disk systems. Here I will present the first detection of an optically thin isotopologue of carbon monoxide that is directly probing the gas surface density profile and chemistry of the disk midplane to radii that lie within the natal region of giant planet birth. Beyond the CO snowline we also detect the presence of striking rings in the emission of hydrocarbons, which we posit is linked to overall carbon and oxygen chemistry throughout the disk. We will discuss an emerging consensus where we are likely observing an active chemistry that leads to the implantation of key C, H, O, and N volatiles into pre-planetary materials with important implications for the formation of worlds such as our own.

New constraints on the chemistry of planet formation

255th National Meeting (2018)

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