Willem Jacob Luyten
Willem Jacob Luyten ( born March 7, 1899 in Semarang, Indonesia, † November 21, 1994 in Minneapolis ) was a Dutch astronomer who lived in the U.S. and worked. He played a key role in determining the mass - luminosity relation of stars, investigated the proper motion of stars, discovered many white dwarfs and some of the nearest neighboring star of the sun as Lutyens star. He worked at the Lick Observatory and Harvard College Observatory and taught at the University of Minnesota.
Life
Luytens ancestors came from the French Provence. The original family name Lutin goes back to lute player, who lived in the 14th century at the court of the Pope in Avignon and later settled in Burgundy and finally the Netherlands.
Luytens parents are from North Holland, however, were migrated to Indonesia, that his time was a Dutch colony. His father was a French teacher at the high school from Semarang, north of the island of Java. Here Willem Jacob was born in 1899. In 1912 the family returned to the Netherlands.
Luytens interest in astronomy grew in 1910 when Halley's comet was visible in the night sky. His first observations he led in 1912 by Java. In the Netherlands, he studied at the Universities of Amsterdam and Leiden. In Leiden he was the first student of Ejnar Hertzsprung. In 1921 he received his doctorate, with his doctoral thesis was based on the evaluation of the visual observation of 13,500 variable stars, which he had performed with the 6- inch ( 15 cm) refractor of the Observatory of Leiden. During his time in Leiden he was in contact with Jacobus Kapteyn, Willem de Sitter, Paul Ehrenfest and Albert Einstein.
1921, Luyten in the U.S., where he worked for two years at the Lick Observatory. Harlow Shapley in 1925 offered him a position at the Harvard College Observatory. Luyten worked seven years for Harvard, where he spent the last two years in Bloemfontein, South Africa. In South Africa, he met his future wife Willemina Miedema, with whom he was married for almost sixty years and had three children.
Although Luyten interested in many of the areas of astronomy, was his special attention to the sizes and the proper motion of the neighboring star of the sun. Particularly striking appeared to him the fact of apparent uneven distribution of stars. In the nearby surroundings of the sun ( 10 parsecs ) there are no red giants and only four luminous stars of spectral type A, although 99 % of the visible with the naked eye stars are more luminous than the sun. He performed precise measurements of proper motions, where he continued Hertz jump thesis that can be inferred from the degree of self-motion and the apparent brightness to the absolute magnitude and thus on the distance. Although this method is not as accurate as the determination of the parallax, but useful for a variety of stars. He noted that of the 700 stars within 10 parsecs around the Sun about 96 % fainter than they are. From 1925 to certain Luyten even the proper motion of over 200,000 stars.
In 1927, a systematic survey of the sky, " Bruce Proper Motion Survey", started. These photographic plates were analyzed, which were created 1896-1910 with the 60 cm refractor ( Bruce telescope) from Arequipa, Peru and abbildeten the entire southern sky. At over 1,000 plates, each exposed for three hours, stars were visible up to magnitude 17. Luyten made to Bloemfontein from over 300 photographic plates, which he compared by blink comparator with the older boards. This 94 263 stars were found with significant proper motions. Most were brighter than the 14th magnitude and showed movements of up to 0.1 seconds of arc per year. The evaluation took decades to complete and the final star catalog was not published until 1963.
When screening a large number of white dwarfs was discovered that the final stage of relatively low-mass stars (like our sun ) represent. 1921 were only three white dwarfs known, in 1963 there were several hundred.
Luyten extended his investigations to the northern sky. Since the Bruce telescope was unsuitable for this purpose because of its southern location, he initiated the "National Geographic / Palomar Observatory Sky Survey ", where he used the 1.2 m Schmidt telescope of Mount Palomar Observatory. Instead of toiling with the blink comparator, the evaluation was done by machine, using a special densitometer. Within a few years this way could the movement of more than 300,000 stars to be determined.
In 1967, Luyten into retirement. For his life's work to him numerous honors were bestowed. In 1968 he received the Bruce Medal of the Astronomical Society of the Pacific, 1970, he was inducted into the National Academy of Sciences.
The asteroid (1964 ) Luyten was named after him.