Day of Archaeology 2011–2017: Global Community, Public Engagement, and Digital Practice.

The Day of Archaeology (http://www.dayofarchaeology.com) was a volunteer-led international archaeological blogging event that ran from 2011 to 2017. The project asked people who define themselves as archaeologists to submit one or more blog posts about their working day on a chosen day in June or July. This article explores the history of the Day of Archaeology project and the practicalities of running a large-scale collaborative blogging project, before examining some of the topics covered in the posts. An assessment of the impact of the project follows. Overall, we hope in this work to answer some of the basic questions regarding this type of collaborative, online, global engagement – what we did, who we reached, what they talked about – and also to provide some insights for any other similar initiatives that may follow us in the future

The origin and abundances of the chemical elements revisited

The basic scheme of nucleosynthesis (building of heavy elements from light ones) has held up very well since it was first proposed more than 30 years ago by E.M. Burbidge, G.R. Burbidge, A.G.W. Cameron, W.A. Fowler, and F. Hoyle. Significant advances in the intervening years include (a) observations of elemental and a few isotopic ratios in many more extrasolar-system sites, including metal-poor dwarf irregular galaxies, where very little has happened, and supernovae and their remnants, where a great deal has happened, (b) recognition of the early universe as good for making all the elements up to helium, (c) resolution of heavy element burning in stars into separate carbon, neon, oxygen, and silicon burning, with fine tuning of the resulting abundances by explosive nucleosynthesis in outgoing supernova shock waves, (d) clarification of the role of Type I supernovae, (e) concordance between elements produced in short-lived and long-lived stars with those that increased quickly and slowly over the history of the galaxy, and (f) calibration of calculations of the evolution and explosion of massive stars against the detailed observations of SN 1987A. The discussion presupposes a reader (a) with some prior knowledge of astronomy at the level of recognizing what is meant by an A star and an AGB star and (b) with at least a mild interest in how we got to where we currently are. © 1991 Springer-Verlag