Evolution of C, N, and O chemistry in planet-forming disks

C2H, HCN, and C18O emission observed towards HD 163296.

The volatile chemistry in disks is expected to evolve over time, though this evolution is poorly constrained observationally. We performed a survey of C2H, HCN, and C18O (tracers of the C, N, and O chemistry) in a sample of disks spanning young embedded sources through evolved protoplanetary disks, offering a systematic view of the volatile chemical evolution in disks. Understanding such chemical evolution is an important step in predicting how the volatile composition of planet-forming material changes at different stages in the disk lifetime

A survey of C2H, HCN, and C18O in protoplanetary disks (arXiv:1904.09315)

An evolutionary study of volatile chemistry in protoplanetary disks (arXiv:2006.12584)

Complex organics in protostars and protoplanetary disks

Low-mass protostars and solar system comets show close similarities in their organic compositions.

A key aim of astrochemistry is to understand the origin and inheritance of complex (6+ atoms) organic molecules throughout the star and planet formation sequence. I have performed observational surveys of complex organics towards protostellar envelopes, protostellar disks, and protoplanetary disks to help further our understanding of the types and abundances of organics present at different stages. Comparisons with comets, the most primitive objects in our solar system, reveal compositional similarities to protostellar material, suggestive of chemical inheritance from the earliest stages of star formation.

Complex organic molecules towards embedded low-mass protostars (arXiv:1705.05338)

Organic complexity in protostellar disk candidates (arXiv:1907.0779)

A survey of CH3CN and HC3N in protoplanetary disks (arXiv:1803.04986)

Experimental studies of ice-phase chemistry

Schematic of different microphysical processes that regulate ice chemistry.

Laboratory studies of ice chemistry offer insight into the energetics and mechanisms that drive chemistry in star-forming environments, a necessary complement to observational studies. My experimental work has focused on understanding (1) the formation of NH4 + salts, which may be important for sequestering nitrogen in comets, and (2) the chemistry of photo-produced oxygen atoms, which can react with hydrocarbons to form organics even at very low temperatures.

Kinetics and mechanisms of the acid-base reaction between NH3 and HCOOH in interstellar ice analogs (arXiv:1608.00010)

Methanol formation via oxygen insertion chemistry in ices (arXiv:1707.01120)

Oxygen atom reactions with C2H6, C2H4, and C2H2 in ices (arXiv:1903.10981)

Phosphorus in protostars

The outflow of B1-a traced by SiO, where PN and PO were detected.

Phosphorus is a key bioelement on Earth, yet there are very few astronomical constraints on how it is inherited during the star formation sequence. We detected the phosphorus molecules PO and PN towards the low-mass protostar B1-a, just the second detection towards a Sun-like (low-mass) star forming region. The phosphorus carriers are emitting from a shocked outflow and have a very low gas-phase abundance, implying that most phosphorus is sequestered in dust grains.

Detection of phosphorus-bearing molecules towards a Solar-type protostar (arXiv:1910.04539)