2007 Annual Science Report
NASA Goddard Space Flight Center Reporting | JUL 2006 – JUN 2007
Accomplishments of Graduate Student Yani Radeva
During this reporting period, Ms. Yana Radeva was a graduate student at the University of Maryland, pursuing her Ph. D. under the joint mentorship of GCA co-I Prof. Michael A’Hearn (Astronomy Dept.) and Michael Mumma (GCA P. I.). Radeva completed her second-year research project during this period. She investigated the organic composition of Oort cloud comet C/2001 WM1 (LINEAR), as revealed in high-dispersion infrared spectra acquired with the NIRSPEC cross-dispersed echelle grating spectrometer at the Keck-2 telescope (Mauna Kea, HI).
At the DPS/AAS Annual Meeting in 2006, Radeva reported provisional quantitative measurements of organic volatiles and water obtained on 25 Nov. 2001 UT. Emission lines were detected from multiple parent species (including H2O, HCN, CH4, C2H2, C2H6, H2CO, CH3OH) and from OH prompt emission. Radeva extracted calibrated spectra and from them obtained provisional rotational temperatures, production rates, relative abundances of organic molecules with respect to H2O, and the ortho-para ratio for H2O.
During this reporting period, she refined her analysis procedures, leading to final quantitative results. Her results demonstrate that WM1 is depleted in its organic chemistry, compared to the “organics-normal” group identified in a previously analyzed sample of Oort cloud comets. WM1 is thus the third “organics-depleted” comet characterized by us, the other two being OC comet C/2000 S4 (LINEAR) and JFC 73P/Schwassman-Wachmann 3.
Radeva, Y. L., Bonev, B. P., Villanueva, G. L., Mumma, M. J., DiSanti, et al. 2006, “The Organic Composition of Comet C/2000 WM1 (LINEAR) Revealed at Infrared Wavelengths”, Poster presentation at DPS/AAS Annual Meeting, (Pasadena, Oct. 2006).
Radeva, Y. L., Bonev, B. P., Mumma, M. J., DiSanti, Villanueva, G. L., et al. 2007, “The Depleted Organic Composition of Comet C/2000 WM1 (LINEAR) as seen at Infrared Wavelengths”, Oral presentation at DPS/AAS Annual Meeting, (Orlando, Oct. 2007).
PROJECT INVESTIGATORS:Yana Radeva