Interstellar Grains: 50 Years On

TL;DR

This paper reviews 50 years of research on interstellar grains, emphasizing the author's contributions and advocating for a biological origin hypothesis that unifies diverse astronomical observations.

Contribution

It highlights the author's pioneering role in developing the graphite-silicate-organic grain model and promotes a biological provenance theory for interstellar grains.

Findings

The graphite-silicate-organic model is rooted in early peer-reviewed work.

A biological origin hypothesis offers a unifying explanation for various data.

The biological model remains controversial but influential.

Abstract

Our understanding of the nature of interstellar grains has evolved considerably over the past half century with the present author and Fred Hoyle being intimately involved at several key stages of progress. The currently fashionable graphite-silicate-organic grain model has all its essential aspects unequivocally traceable to original peer-reviewed publications by the author and/or Fred Hoyle. The prevailing reluctance to accept these clear-cut priorities may be linked to our further work that argued for interstellar grains and organics to have a biological provenance - a position perceived as heretical. The biological model, however, continues to provide a powerful unifying hypothesis for a vast amount of otherwise disconnected and disparate astronomical data.