Letters of Intent received in 2019

LoI 2021-2115
GA Focus Meeting "Angelo Secchi and Stellar Spectroscopy"

Date: 20 August 2021 to 20 August 2021
Category: Focus meetings (GA)
Location: Busan, Korea, Rep of
Contact: ILEANA CHINNICI (chinnici@astropa.inaf.it)
Coordinating division: Division C Education, Outreach and Heritage
Other divisions:
Co-Chairs of SOC: CHINNICI Ileana (INAF, Palermo Observatory)
STERKEN Christian (Vrije Universiteit, Brussel)
CORBALLY, Christian (Vatican Observatory)
HEARNSHAW John (UNiversity of Canterbury, Christchurch)



- HISTORY OF ASTROPHYSICS: Angelo Secchi (1818-1878) was one of the protagonists of the transition from classical astronomy (celestial mechanics) to a new astronomy (astronomical spectroscopy), later called astrophysics.
- HISTORY OF SPECTRAL CLASSIFICATION: Secchi's early spectral classification of stars (1863-1872) was used as a reference for late 19th century classifications, especially Harvard classification.
- HISTORY OF JESUIT ASTRONOMY: Jesuits' contribution to astronomy was remarkable, not only for researches and speculations, but also for spreading the practise of astronomy all over the world. Secchi was a key-figure in this respect.
- HISTORY OF SOLAR PHYSICS: Secchi's book "Le Soleil" was one of the most important treatise of solar physics in 19th century and had a significant impact in the development of this branch of astronomy.
- HISTORY OF PLANETARY ASTRONOMY: Early spectroscopic observations of planets and comets were carried out by Secchi and other pioneers in astronomical spectroscopy.



Year 2021 marks the 150th anniversary of the establishment of the Italian Spectroscopical Society, the first astrophysical society, whose main proposer was Fr. Angelo Secchi, S.J. (1818-1878), a founder of modern astrophysics, who carried out pioneering studies in spectroscopy of stars, comets and planets and in solar physics; The XXXI IAU General Assembly can therefore become an important opportunity to recognize the contributions of this early astrophysicist in the development of astronomical spectroscopy and in the definition of the new discipline of astrophysics.
The Focus Meeting will include an extended historical section on early astrophysical research and a few contributions on their current developments. Secchi's works were interconnected with those of the other protagonists of early astrophysics and his figure can therefore be a crossing-point for an examination of the context where the transition from classical astronomy to modern astrophysics took place.

Fr. Angelo Secchi (1818-1878) represents an extraordinary scientist and man in an extraordinary epoch. A Jesuit, refugee for political reasons in the years 1848-1850 at the Stonyhurst College in England and at the Observatory of Georgetown University in United States, after his return to Italy he took charge of the Observatory of Collegio Romano and produced a large body of astronomical observations, being spectroscopy (of stars as well as of comets and planets) his main research activity. He proposed one of the first spectral classification of stars, which will be used, later, as a reference scheme for other important classification works (i. e. Harvard, end of 19th century). A man of several interests (including meteorology, geodesy, archaeology, etc.), he also promoted scientific cooperation and was co-founder of the Italian Society of Spectroscopists (1871), which was mainly aimed at monitoring solar activity. He was the author of many important astronomical books; his volume "Le Soleil" was one of the most important treatise of solar physics in 19th century and had a significant impact in the development of this branch of astronomy. Secchi also carried out the first spectroscopic observations of Uranus (1859) and was among the first astronomers who observed a cometary spectrum (1864).

Secchi contributed to determine an epochal change in astronomy, when, moving eventually away from positional astronomy and celestial mechanics, the intimate nature of stars and planets – notably their compositions – became the main subject of investigation. In this context, he stands among the founders of modern astrophysics in 19th century, together with William Huggins, Norman J. Lockyer, Jules C. Janssen, Carl H. Vogel, Charles A. Young and others: their scientific exchanges and debates led to the advancement of spectral classification, solar physics and planetary spectroscopy and to definitely establish the fundamental of astrophysics.

The Focus Meeting will present a first session with a wide description of the historical and scientific context where Secchi lived and operated; Secchi’s connections with the other pioneers of astrophysics; the evolution of spectral classification and /or spectroscopic instruments. A second session will illustrate the current perspectives of those astronomical branches that Secchi contributed to develop.