Astronomy and Astrophysics – Astronomy
Scientific paper
Dec 2000
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000dps....32.6530k&link_type=abstract
American Astronomical Society, DPS Meeting #32, #65.30; Bulletin of the American Astronomical Society, Vol. 32, p.1645
Astronomy and Astrophysics
Astronomy
Scientific paper
In recent years millimeter-wave interferometers have imaged the gas and dust surrounding over a dozen T Tauri and Herbig Ae stars (see Sargent 1996 in Disks and Outflows from Young Stars, pp. 1-23, for review). These studies demonstrate the potential to improve dramatically our understanding of disk physical and chemical structure, providing unique insights that will ultimately enable a more comprehensive understanding of star and planet formation. In particular, through the comparison of disk properties such as (D/H) fractionation with those of comets and Kuiper belt objects the origin of primitive solar system bodies can be investigated. In this study, 1.3 mm transitions of the deuterated species DCN and HDO were detected toward the T Tauri star LkCa 15 using the Owens Valley Radio Observatory Millimeter Array (for previous observations of various molecules toward LkCa 15 see Qi, PhD thesis, 2000). The resulting DCN abundance was compared to that found for HCN and H13CN. The measured intensity ratios of the (DCN/HCN) transitions lead to (D/H) ratios of <0.5, but are clearly influenced by opacity in the HCN 1-0 transition. Observations of the optically thin isotope H13CN, yield an estimated DCN/HCN ratio of ~ 0.01. This value is much larger than the estimated protosolar D/H of ~ 1.6e-5 (Gautier & Morel 1997 A&A 323, L9) and quite close to that observed in dark molecular clouds, 0.01-0.05 (Wooten 1987 Astrochem 120, 311), indicating that the assignment of cometary origin using D/H fractionation is a complicated endeavor. Through the combination of the observations presented here and chemical models of circumstellar material, the temperature dependence of fractionation and enrichment of deuterium through gas-grain surface reactions can be explored. Further, although H2O cannot be observed and thus HDO/H2O was not measured, differences in the morphology of maps of the observed emission from DCN and HDO may shed light on differences in fractionation seen in the material around young stars. This work was supported by the NASA Graduate Student Researchers Program, NGT5-50231, and the National Science Foundation, AST 9981546.
Blake Geoffrey A.
Kessler Jacqueline E.
Qi Chong
No associations
LandOfFree
D/H Fractionation in Circumstellar Disks does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with D/H Fractionation in Circumstellar Disks, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and D/H Fractionation in Circumstellar Disks will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1042082