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dc.contributor.authorSmith, Rachel L.
dc.contributor.authorBlake, Geoffrey
dc.contributor.authorBoogert, Adwin
dc.contributor.authorPontoppidan, Klaus Martin
dc.contributor.authorLockwood, Alexandra C.
dc.date.accessioned2016-01-28T07:13:59Z
dc.date.available2016-01-28T07:13:59Z
dc.date.issued2015-04
dc.identifier.urihttp://hdl.handle.net/10754/595124
dc.description.abstractObservations of CO isotopologues taken at high spectral resolution toward young stellar objects (YSOs) are valuable tools for investigating protoplanetary chemical reservoirs, and enable robust comparisons between YSOs and solar system material (meteorites and the Sun). Investigating a range of YSO environments also helps parameterize variations in the distribution and evolution of carbon-based molecules, furthering an understanding of prebiotic chemistry. We have begun a wide survey of massive YSOs using Keck-NIRSPEC at high spectral resolution (R=25,000). Fundamental and first-overtone near-IR CO rovibrational absorption spectra have thus far been obtained toward 14 massive, luminous YSOs at Galactocentric radii (RGC) ranging from ~4.5 to 9.7 kpc. From these data we can obtain precise [12CO]/[13CO] gas-phase abundance ratios along a Galactic gradient, and [12CO]/[13CO]Gas can be further evaluated against published [12CO2]/[13CO2]Ice and [12CO]/[13CO]Ice because all observations are in absorption, a robust study of molecular inheritance is possible by virtue of comparing 12C/13C along the same lines-of-sight. Initial results for cold CO gas at RGC ~ 6.1 kpc and 9.4 kpc reveal [12C16O]/[13C16O] of 59+/‑8 and 74+/‑3, respectively, roughly following an expected 12C/13C Galactic gradient. Thus far, we find [12CO]/[13CO] in the cold CO gas to be lower than [12CO2]/[13CO2]Ice, suggesting that CO2 may not originate from CO reservoirs as often assumed. While very high-resolution observations of CO gas toward low-mass YSOs observed with VLT-CRIRES show significant heterogeneity in [12CO]/[13CO] at RGC ~ 8 kpc, this dispersion is not found for the massive YSOs. Both the low-mass and massive YSOs have higher [12CO]/[13CO] in warm vs. cold gas, and both show signatures suggesting possible interplay between CO ice and gas reservoirs. Overall, our results indicate that carbon isotopic evolution in massive YSO environments may follow different paths compared to low-mass YSOs, and assumptions used in determining carbon-based molecular pathways should be considered in concert with robust observations of a range of YSO environments.
dc.relation.urlhttp://adsabs.harvard.edu/abs/2015IAUGA..2257444S
dc.titleInvestigating Molecular Inheritance of Carbon in Star-forming Regions along a Galactic Gradient
dc.typePresentation
dc.conference.date12-17 April, 2015
dc.conference.nameEGU General Assembly 2015
dc.conference.locationVienna, Austria
dc.contributor.institutionNC Museum of Natural Sciences
dc.contributor.institutionCalifornia Institute of Technology
dc.contributor.institutionSOFIA Science Center/NASA AMES Research Center
dc.contributor.institutionSpace Telescope Science Institute
kaust.personLockwood, Alexandra C.


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