Jacobus Kapteyn

Jacobus Cornelius Kapteyn (January 19th, 1851 - June 18th, 1922) was a Astronome Dutch, known for its intensive study of the Milky Way and like discoverer of the first evidence of galactic rotation.

Kapteyn was born with Barneveld, and entered to the university of Utrecht in 1868 to study there the Mathématiques and the Physique. Starting from 1875, after having completed its thesis, it will work during three years with the Observatoire of Leyde, before becoming the first professor of Astronomie and theoretical Mécanique at the university of Groningue, where it will remain until his retirement in 1921.

Between 1876 and 1900, for lack of observatory at its disposal, it proposed to study the photographic plates taken by David Gill, which led at the time the photographic cover of the star S of the southern hemisphere, via the observatory of the Cape, in South Africa. This collaboration will give place to the publication of Cape Photographic Durchmusterung , a Catalog of stars listing the position and the magnitude of 454  875 stars of the southern hemisphere.

In 1897, during its work on these boards, it discovered the star of Kapteyn. It was at the time the star having the own Mouvement fastest never discovered. It from now on in second position, is détrôné by the star of Barnard.

In 1904, studying the own movements of stars, Kapteyn foot-note that those were not random, as it at the time was believed; the stars could be catalogued in two flows, moving in opposite directions. It will be realized later that the data of Kapteyn brought the first proof of the rotation of the Galaxie, which will lead to discovered differential Rotation by Bertil Lindblad and Jan Oort.

In 1906, Kapteyn proposed a plan for the study of the distribution of stars in the Galaxy, by counting stars in various directions. This study used the measurement of the Magnitude connect, of the spectral Type, the radial Speed and the own Mouvement of stars in 206 zones. This enormous project was the first statistical analysis coordinated in astronomy, and implied the collaboration of more than 40 different observatories.

Honorary distinctions

Rewards Éponymes

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