In a previous post I took a look at the collaboration numbers among astronomers, and verified that groups of more than five coauthors have become prevalent in the last five years or so. A natural question that arises from this is “What are the most popular topics in astronomy publications?”.
To answer this question, one can look for the “Keywords” section that appears in most “recent” (i.e., from 1970 onwards) astronomy papers, and count the number of actual keywords listed. Once again, the NASA ADS Astronomy Abstract Service proves invaluable for this task. So without further ado, here are the results:
These keywords correspond to refereed articles only, and they have all been converted to lower case. The search gave 128, 394 different keywords. The 3 least-frequent keywords were “zz ceti”, “zz psc” and “zz uma”, with only one instance each. The keyword “dark energy” was number 311 in the list, “mars” was number 881, and “extrasolar planets” was number 1,410.
It is also interesting to look at the frequency of keywords over time. I picked four keywords (“stars: atmospheres”, “brown dwarfs”, “gamma rays: observations”, and “astrochemistry”), and plotted their available yearly counts since 1990. I did this for each of three journals: The Astrophysical Journal (ApJ, shown in red below), Monthly Notices of the Royal Astronomical Society (MNRAS, blue), and Astronomy & Astrophysics (A & A, green). I also included the yearly counts for all the journals combined (shown in black):
Check out this cool interactive website built by Stefano Meschiari, in which you can choose a keyword and see its behavior in time.