Magnetic Fields in O, B, and A Stars

The 'AAS-IoP Astronomy ebooks' series, to which this volume is a recent addition, is rapidly becoming established as a major source of specialized monographs, with more than 30 books already available at the time of writing, and a similar number in preparation (according to the series' website). Many (though not all) of the titles are so specialized that in days past one may have associated them with review papers, not books. The volume under review is no exception. The authors are able to review the literature (to which they are substantial contributors) rather thoroughly, incorporating a lot of detail on individual objects. I was left wondering who would want to work through such an exhaustive treatise; the stated aim is to educate scientists working on [early-type] stars, who are not yet expert in magnetic field studies . Well, okay, though I'd have thought that active researchers will already be familiar with the material, while those outside the field may find it hard to see the wood for the trees. Perhaps the answer is new postgraduate students about to undertake a relevant project, though that can't be more than a handful of people each year. In any case, this is really a book for the specialist, although a couple of introductory chapters provide a more general introduction to the principles and practice of magnetic-field measurement thatmay be of wider interest. Ian D. Howarth, April 2022, The Observatory -- Ian D. Howarth * The Observatory *