Astrophysics in 1991

Abstract

ABSTRACT. Science, notoriously, progresses amoeba-like, thrusting out pseudopods in unpredictable directions and dragging the rest of the body after or, occasionally, retreating in disorder. This review attempts to shine a narrow and not unprejudiced beam of light on areas of astrophysics where the author believes that something interesting happened in 1991. Length scales range from the kilometers of comets to the gigaparsecs of cosmology, and time scales from milliseconds upward. Eight selfcontained sections discuss the surface of Venus, late activity in Comet Halley, convective overshoot, blue stragglers, new examples and kinds of X-ray binaries and recycled pulsars, hard X and y rays from the galactic-center region, microlensing, and biased cold dark matter. The last two sections contain very short descriptions, with references, of a number of items that did not fit into the main sections but seemed a shame to leave out.

Decaying neutrinos and the nature of the dark matter in galaxy clusters

“…In a comprehensive article on the astronomical developments of 1991, Trimble (1992) included a section entitled "The Decay and Death of Sciama's Particle." This judgmental title was based on the failure of Davidsen et al ( 1991 ) to detect the predicted emission line (at ~ 15 eV in the rest frame) from the dark matter (DM) in the cluster A665.…”