“Sugli spettri prismatici della luce delle stelle fisse”
(on prismatic spectra from light and fixed stars)

INAF – Rome Astronomical Observatory

This is the first memoir by Secchi on stellar spectra. On the left-hand corner, the shows the scheme of the stellar spectrometer that he used for this type of research and, next to it, the scheme of the thermosheliometer. Also included are the stellar spectra observed by Secchi. Based on his first studies, Secchi formulated his spectral classification, which was published in two memoirs of 1867 and 1869; in the latter he extended his original division into classes, by adding a fourth class comprising red stars, whose typical spectrum was chosen by Secchi as being that of star n. 152 from the Schjellerup catalogue. In 1872 Secchi summarized his results in a third memoir, in which he also added the observations carried out with the objective prism. [i.c.]

Bibl.: Chinnici 1999.