Anders Jonas Ångström

Summary

Anders Jonas Ångström (Swedish pronunciation: ) (born August 13, 1814, in Timrå, Västernorrland and died June 21, 1874 in Uppsala, Uppland) was a Swedish astronomer and physicist. He is one of the founders of spectroscopy. He is known for having established a catalog of Fraunhofer lines of the Sun in which he measured the wavelengths with a unit of length equal to 10-10 m, which was subsequently called the ångström.

Anders Jonas Ångström was born on the Lögdö steel mill estate in the parish of Hässjö in the municipality of Timrå in the historical province of Medelpad. He was the second son of Johann Ångström, a Lutheran minister, and Anna Catharina Thunberg. When Anders was only a few years old, his father was transferred to Ullånger and a few years later to Sättna near Sundsval. The pastor had a very low salary and had to cultivate his garden to feed his family. However, he did everything possible to ensure that his three sons received a higher education. Anders went to high school in Härnösand. He studied mathematics and physics at the University of Uppsala from 1833. He was awarded the title of privat docent in physics in 1839 and immediately became a lecturer in physics at Uppsala University when the chair of physics was vacant. His older brother, Johan, was a physician and botanist. His younger brother, Carl Arendt, was a mining engineer.

Anders joined the Stockholm Observatory in 1842 to acquire practical astronomical observation. The following year he was appointed head of the Uppsala Observatory while continuing to teach physics and astronomy at Uppsala University. In 1846-1847, he took charge of the astronomy courses during the absence of the full professor.

In 1856, Anders Ångström married Augusta Carolina Bédoire, who came from an opulent family of import-export merchants, bankers and industrialists, founded in the second half of the 17th century by Jean Bédoire, known as the Elder, a Huguenot born in Saintonge, who had established himself as an importer of French wine in Stockholm, where he was also a representative of the Compagnie de Commerce du Nord founded by Colbert in 1669. Anders and Augusta had a son, Knut Johan, born on January 12, 1857, who became professor of physics and researcher at the University of Uppsala in 1891.

In 1858, after two years as a professor of physics, Anders Ångström succeeded Adolph Ferdinand Svanberg as chair of physics at Uppsala University. At the age of 44, he finally had a stable position. The following year, the physicists at Uppsala University moved to a new building, which allowed Ångström to introduce practical work into the physics master”s degree course. However, Ångström was more of a researcher than a teacher. He was rather reserved and could even appear inaccessible to some students.

For many years he served as Secretary of the Uppsala Academy of Sciences to the satisfaction of the Swedish and foreign members.

Anders Jonas Ångström died of meningitis in Uppsala on June 21, 1874 (at the age of 59), a few weeks before his 60th birthday and 6 months after being elected on December 22, 1873, as a corresponding member of the Academy of Sciences in Paris.

Terrestrial magnetism

The study of terrestrial magnetism was part of the astronomers” skills. Angstrôm became interested in this field at the beginning of his career as a teacher-researcher. He took readings of the magnetic field intensity in different places in Sweden. In 1843 and 1844, he traveled to France and Germany where he met the specialist in terrestrial magnetism Johann von Lamont. The Stockholm Academy of Sciences also asked him to analyze the magnetic field measurements taken during the 1851-1853 round-the-world expedition of the Royal Swedish Navy frigate L”Eugénie. He would not complete this work until shortly before his death.

Spectroscopy

A. J. Ångström published a paper in Swedish in 1853 entitled Optiska Undersökningar (Optical Research) which was translated and published in English two years later. He established the principles of spectral analysis.

From 1859 to 1861, the physicist Gustav Kirchhoff and the chemist Robert Bunsen made a systematic study of the emission spectra of about thirty elements. In 1872, Ångström received the Rumford Medal of the Royal Society “for discovering that an incandescent gas emits light lines of the same wavelength as those it absorbs when cold. In awarding the medal, Sir Edward Sabine said that the discoverer of this fundamental principle deserved to be counted among the founders of spectral analysis.

Solar spectrum

In 1859, Julius Plücker identified the Hα and Hβ emission lines of Hydrogen with the Fraunhofer C and F lines in sunlight. In 1862, Ångström discovered that the Fraunhofer f and h lines in the solar spectrum corresponded to the Hγ and Hδ lines of hydrogen. He deduced that Hydrogen is present in the solar atmosphere, as well as other elements.

The identification of the four Hydrogen lines and the precise measurement of their wavelengths allowed Johann Jakob Balmer to establish the relationship between them and Niels Bohr to propose his model of the Hydrogen atom which opened the field of quantum mechanics.

In 1868, Angström published the result of five years of research in the form of a book in French entitled Recherches sur le spectre solaire, Spectre normal du soleil in which he described his measuring instruments and methods of calculating wavelengths. To analyze the light, he had a spectrometer and three gratings with 220, 132 and 88 lines per millimeter. It is the network of 132 lines

In his book, Angström gave a list of wavelengths of more than 1000 Fraunhofer lines and, for some, their origin. He added an atlas in which the spectrum from 4000 to 7000 Angström (drawn by Robert Thalén) was represented graphically in 12 segments spread over 6 plates. This atlas was published separately in 1869 under the title Normal spectrum of the sun: Atlas, containing the wavelengths of the Frauenhoferian lines given in 1

The atlas of Ångström and Thalén will indeed be authoritative until the end of the century and the unit of measurement they defined will be universally adopted, first by spectroscopists, then by astronomers and finally by atomic physicists.

Spectrum of an aurora borealis

Ångström was the first to obtain the spectrum of an aurora borealis in 1867. He detected the characteristic oxygen line in the yellow-green region at 557.7 nm, which is sometimes called the Ångström line. But he was mistaken in assuming that this line should also be observed in zodiacal light.

Heat studies

Ångström developed a method for measuring the thermal conductivity of materials. It consisted of applying pulses of heat to the end of a rod and measuring the difference in temperature at its two ends as a function of time. In this way he discovered that thermal conductivity is proportional to electrical conductivity.

Anders Jonas Angström has been elected to many academies and has received numerous awards:

Notoriety

Its name was given :

External links

Sources

  1. Anders Jonas Ångström
  2. Anders Jonas Ångström