Using NOEMA, I targeted 5 outbursting sources and was sensitive to four CO
isotopologues. All 5 had optically thin emission of C17O, and I used this to determine
a mass within ~1000 au around each star. All 5 sources proved to be gravitationally unstable
within this region.
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Chemical Accounting of an Outbursting Object with NOEMA
Calahan, J.K., Bergin E.A., van't Hoff M. et al.
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Astrophysical Journal 975, 2 (2024)
V1057 Cyg is a classic FU Ori-type object, a suspected binary system that still has a
enough mass within 1000 au to be considered gravitationally unstable. This source stood
out in our NOEMA survey as being very line-rich, with strong detections of multiple
complext organic molecules, sulfur bearing molecules, and a ~3 sigma detection of HDO.
V1057 Cyg then is used as a chemical bridge, connecting between protostars, protoplanetary disks,
and comets.
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Taking the Temperature of a Massive Planet-hosting Disk
Calahan, J.K., Bergin E.A., Zhang Ke et al.
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Astrophysical Journal Supplemental Series 257, 1 (2021)
I reproduce the spatially resolved CO emission and SED in the HD 163296 protoplanetary disk,
and produce a 2D temperature structure that has been used for future chemical modeling and planet
formation studies. HD 163296 has large gaps and rings, and I explore the impact of assumed
gas depletion within those dust gaps, and see that within the gap the temperature can increase by 10% and
the local UV field is elevated.
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Hunting for Inflow in Starless Cores
Calahan, J.K., Shirley Y., Svoboda B. et al.
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Astrophysical Journal 862, 1 (2018)
The first sign of star formation is infall within a core of dust and gas.
Using the Bolocam Galactice Plane Survey, we followed up 101 starless cores
with the 12m telescope on Kitt Peak, looking for signs of infall in the HCO+ 1-0 line.
We find that 6% of our sample show infall motion. This project was also a teaching
opportunity for the Astronomy Club at the University of Arizona, and most co-authors were
fellow undergraduates that I brought to the telescope, and I taught them about the project, and
how to help with observations.