Kathryn A. Dyl

Millimeter-Wave and Vibrational State Assignments for the Rotational Spectrum of Glycolaldehyde

Glycolaldehyde (CHOCH2OH), the simplest two-carbon α-hydroxy aldehyde, has become of great interest in the field of astrochemistry due to its recent detection toward the Sagittarius B2 (N-LMH) molecular cloud. The original interstellar identification was based on an extrapolation of prior microwave rotational spectroscopy of glycolaldehyde. The millimeter and submillimeter spectra of this molecule from 128 to 354 GHz were subsequently measured after the interstellar detection. We present here the millimeter spectrum of this molecule from 72 to 122.5 GHz along with a combined millimeter and submillimeter pure rotational analysis of the ground and the first three vibrationally excited states of glycolaldehyde that enables a more complete molecular partition function to be determined. These results show that excited vibrational state contributions to the partition function are an important consideration when determining the column density of a molecule with low-lying torsional states.

Early Solar System hydrothermal activity in chondritic asteroids on 1–10-year timescales

Chondritic meteorites are considered the most primitive remnants of planetesimals from the early Solar System. As undifferentiated objects, they also display widespread evidence of water–rock interaction on the parent body. Understanding this history has implications for the formation of planetary bodies, the delivery of water to the inner Solar System, and the formation of prebiotic molecules. The timescales of water–rock reactions in these early objects, however, are largely unknown. Here, we report evidence for short-lived water–rock reactions in the highly metamorphosed ordinary chondrite breccia Villalbeto de la Peña (L6). An exotic clast (d = 2cm) has coexisting variations in feldspar composition and oxygen isotope ratios that can only result from hydrothermal conditions. The profiles were modeled at T = 800 °C and P(H2O) = 1 bar using modified grain-boundary diffusion parameters for oxygen self-diffusion and reaction rates of NaSiCa-1Al-1 exchange in a fumarole. The geochemical data are consistent with hydrothermal activity on the parent body lasting only 1–10 y. This result has wide-ranging implications for the geological history of chondritic asteroids.