Protostars and Planets VI, Heidelberg, July 15-20, 2013

Poster 1S027

Observations of isotopic heterogeneities toward embedded cores and binary systems: potential tracers of varying chemical evolutionary pathways in protostellar gas

Smith, Rachel L. (North Carolina Museum of Natural Sciences; Appalachian State University)
Pontoppidan, Klaus M. (Space Telescope Science Institute)
Blake, Geoffrey A. (California Institute of Technology)
Boogert, A.C. Adwin (IPAC, NASA Herschel Science Center, Caltech)
Lockwood, Alexandra C. (California Institute of Technology)

Detailed observations of protostellar gas have enabled the study of isotopic anomalies and peculiarities related to solar system chemical evolution, including the discrepancy in 12C/13C between the solar system and local ISM, and the oxygen isotope anomaly observed in meteorites. Further, comparing targets differing in mass, morphology, parent cloud and galactocentric radius offers an expanded view into the protostellar evolutionary process across a range of potential protoplanetary systems. Using the near-infrared CO rovibrational bands obtained with VLT-CRIRES at very high resolution (R ~ 95,000), we derived precise column densities of observable CO isotopologues (12C16O, 13C16O, 12C18O and 12C17O) toward 13 lines-of-site, representing 7 local star-forming clouds. Sources ranged from low-mass embedded cores, protostellar disks, foreground clouds, including 3 binary systems. We found significant heterogeneity in 12CO/13CO abundance ratios (~ 85 to 165) as compared to the solar system and local ISM, which may be in part due to the interplay between the CO ice and gas reservoirs as most strongly evidenced in our cold-gas sources. The finding of more similar values in 12CO/13CO toward the binary systems DoAr24E (Ophiuchus), EC 90 (Serpens), and potentially for VV CrA (Corona Australis), suggests that these data could be tracing homogeneities in chemical evolutionary pathways in binary gas reservoirs (spanning a radius of a few hundred AU) as compared to embedded cores separated in either the same parent cloud or between star-forming clouds. Heterogeneities in oxygen isotope ratios are found toward several objects in the same star-forming cloud (Ophiuchus) and between objects in 5 different clouds, with a potential correlation with evolutionary stage. Using Keck-NIRSPEC (R ~ 25,000), we have recently expanded these observations of protostellar carbon and oxygen reservoirs to include high mass, high luminosity protostars at varying locations toward the Galactic plane.

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