stereoisomer Archives

Observed Stereoisomeric Ratio (OSR) - defined as the column density ratio between the higher and the lower-energy isomer - for the different stereoisomeric pairs gathered in Table 1 (points), overlaid with the thermodynamic equilibrium prediction (g×e−∆E/Tkin at g = 1, colored area), as a function of the relative energy (∆E= Ehigher- Elower) between isomers. The points corresponding to the detections are colored according to the particular source Tkin (see Tables 1 and 2), following the color code of the vertical bar. For CH3CH2OH, CH3CH2OCHO, CH2CHCH2CN, CH3CH2CH2CN and (CH3)2CHOH, the observational points were “corrected” (indicated with *) accounting for the double degeneracy of one of the isomers in the pair (the higher-energy for the first three, the lower-energy for the last two), multiplying the corresponding ratios shown in Table 1 by 1/g=1/2, 1/2, 1/2, 2 and 2, respectively, to match the displayed thermodynamic prediction which omits this fact. -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Imaging & Spectroscopy, Status Report

Interstellar Stereoisomerism

by Keith CowingMarch 29, 2026March 29, 2026

The increasing detection of new molecules in the interstellar medium (ISM) shows that stereoisomerism is a fundamental contributor to interstellar molecular complexity.

A diagram of left-handed and right-handed versions of the amino acid isovaline, found in the Murchison meteorite. NASA

Astrochemistry, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Comets and Asteroids, Genomics, Proteomics, Bioinformatics, Imaging & Spectroscopy, Interstellar, Meteorites & Asteroids, Origin & Evolution of Life, Press Release

Astrochemistry: The Mystery of Life’s Handedness Deepens

by Keith CowingNovember 22, 2024November 22, 2024

The mystery of why life uses molecules with specific orientations has deepened with a NASA-funded discovery that RNA — a key molecule thought to have potentially held the instructions for […]