Cornelis Easton:The Milky Way as a spiral galaxy

TL;DR

Cornelis Easton was an amateur astronomer who made significant contributions to mapping the Milky Way, proposing its spiral structure, and studying star density correlations, with his work influencing early galactic models.

Contribution

The paper highlights Easton's novel proposal of the Milky Way as a spiral galaxy and his detailed mapping and analysis of its structure, which was pioneering for his time.

Findings

Easton proposed the spiral structure of the Milky Way.

He created detailed maps and isophotal charts of the Milky Way.

Easton identified correlations between star density and surface brightness.

Abstract

Cornelis Easton (1864-1929) became a journalist and newspaper editor. During most of his career he was active as an amateur astronomer and contributed important papers in international astronomical journals This concerned three areas. The first was mapping the Milky Way. The book, La Voie Lactee dans l'hemisphere boreal, which he published in 1893, made some impression. Since it had in addition to drawings of the surface brightness of the Milky Way, also extensive descriptions and discussions of features in the structure and a comprehensive, essentially complete, listing and discussion on everything that had ever been published on the Milky Way. Later he produce an isophotal chart and used photographs to improve the map. Easton had been struck by the idea that what he saw was actually a spiral nebula, but then seen edge-on. Considering bright and dark areas he proposed a form for the spiral in the Milky Way System with the center in the direction of the constellation Cygnus. His publications on this Theory of the Milky Way in the Astrophysical Journal in 1900 and 1913 drew much attention, although many astronomers, including Jacobus Kapteyn, kept quite some reservations. The third area concerned correlations between surface densities of stars and surface brightness of the Milky Way. Easton maintained that there was such a correlation for relatively bright stars. T There is a publication Easton failed to include in his list of his publications, namely an 1894 short article in Nature. The elliptical companion NGC205 of the Andromeda Nebula between had on in 1874 and 1889 rotated by 15 degrees. Isophote twists are responsible for the apparent rotation. In 1903 Kapteyn and the University of Groningen bestowed an honorary doctorate upon Easton.