Discovery of double stars by Giovanni Battista Hodierna in 1654

TL;DR

This paper uncovers Giovanni Battista Hodierna's early work on double stars from 1654, identifying star pairs and confirming some as physically bound, predating the more well-known astronomers Mayer and Herschel.

Contribution

It reveals Hodierna's pioneering catalogue of stellar binaries from 1654, predating Mayer and Herschel, and re-evaluates historical understanding of double star discovery.

Findings

Identified 12 primary stars and 11 multiple systems from Hodierna's 1654 catalogue.

Confirmed four systems as physically bound using modern data.

Revealed Hodierna's early contribution to double star astronomy.

Abstract

It has been generally accepted that the originators of the double star astronomy were Christian Mayer and William Herschel. We recovered the memory of the poorly known Italian astronomer Giovanni Battista Hodierna, who published the first catalogue of stellar binaries over a century before Mayer and Herschel. We analysed the fourth section of 1654 G. B. Hodierna's book "De systemate orbis cometici deque admirandis coeli characteribus". There, Hodierna listed a dozen pairs of stars whose identification with modern star names had been lost for centuries. To identify the pairs, we used Hodierna's Latin descriptions of location in constellations for all primary stars, ecliptic coordinates and angular separations to companions for some, and the Washington Double Star, Hipparcos, and Gaia catalogues. We were able to identify the twelve primaries and eleven multiple systems with companions, of which nine were double and two were triple. Besides, with up-to-date data, we confirmed that four systems are physically bound: Atlas and Pleione, alpha1,2 Lib, nu1,2 Dra, and theta1 Ori A, C, and D. The other seven pairs are alignments of very bright stars at different distances.