Investigating Molecular Inheritance of Carbon in Star-forming Regions along a Galactic Gradient

Handle URI:
http://hdl.handle.net/10754/595124
Title:
Investigating Molecular Inheritance of Carbon in Star-forming Regions along a Galactic Gradient
Authors:
Smith, Rachel L.; Blake, Geoffrey; Boogert, Adwin; Pontoppidan, Klaus Martin; Lockwood, Alexandra C.
Abstract:
Observations 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.
Conference/Event name:
EGU General Assembly 2015
Issue Date:
Apr-2015
Type:
Presentation
Additional Links:
http://adsabs.harvard.edu/abs/2015IAUGA..2257444S
Appears in Collections:
Presentations

Full metadata record

DC FieldValue Language
dc.contributor.authorSmith, Rachel L.en
dc.contributor.authorBlake, Geoffreyen
dc.contributor.authorBoogert, Adwinen
dc.contributor.authorPontoppidan, Klaus Martinen
dc.contributor.authorLockwood, Alexandra C.en
dc.date.accessioned2016-01-28T07:13:59Zen
dc.date.available2016-01-28T07:13:59Zen
dc.date.issued2015-04en
dc.identifier.urihttp://hdl.handle.net/10754/595124en
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.en
dc.relation.urlhttp://adsabs.harvard.edu/abs/2015IAUGA..2257444Sen
dc.titleInvestigating Molecular Inheritance of Carbon in Star-forming Regions along a Galactic Gradienten
dc.typePresentationen
dc.conference.date12-17 April, 2015en
dc.conference.nameEGU General Assembly 2015en
dc.conference.locationVienna, Austriaen
dc.contributor.institutionNC Museum of Natural Sciencesen
dc.contributor.institutionCalifornia Institute of Technologyen
dc.contributor.institutionSOFIA Science Center/NASA AMES Research Centeren
dc.contributor.institutionSpace Telescope Science Instituteen
kaust.authorLockwood, Alexandra C.en
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