Karl Nikolaus Adalbert Krueger (9 December 1832 – 21 April 1896) was a German

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...

. Born in Marienburg,

Prussia Prussia, , Old Prussian: ''Prūsa'' or ''Prūsija'' was a German state on the southeast coast of the Baltic Sea. It formed the German Empire under Prussian rule when it united the German states in 1871. It was ''de facto'' dissolved by an ...

(now Malbork,

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...

), he was editor of '' Astronomische Nachrichten ''from 1881 until his death. Krueger died of a heart condition in

Kiel Kiel () is the capital and most populous city in the northern German state of Schleswig-Holstein, with a population of 246,243 (2021). Kiel lies approximately north of Hamburg. Due to its geographic location in the southeast of the Jutland ...

at the age of 63.

Life and work

In 1851, Krueger entered the University of Berlin where he studied mathematics and science. In 1853, showing a special preference for astronomical studies, Krueger moved to the

University of Bonn The Rhenish Friedrich Wilhelm University of Bonn (german: Rheinische Friedrich-Wilhelms-Universität Bonn) is a public research university located in Bonn, North Rhine-Westphalia, Germany. It was founded in its present form as the ( en, Rhine ...

and became an assistant to the astronomer

Friedrich Wilhelm Argelander Friedrich Wilhelm August Argelander (22 March 1799 – 17 February 1875) was a German astronomer. He is known for his determinations of stellar brightnesses, positions, and distances. Life and work Argelander was born in Memel in the Kingd ...

at the Bonn Observatory. Under Argelander's supervision he produced data for the comprehensive astrometric star catalogue known as the Bonner Durchmusterung, together with fellow student

Eduard Schönfeld Eduard Schönfeld (22 December 18281 May 1891) was a German astronomer. Education Schönfeld was born at Hildburghausen, in the Duchy of Saxe-Meiningen, where he had a distinguished career at the gymnasium. On leaving the gymnasium, he desired t ...

. Starting in Bonn, he undertook a lifelong study of the orbit of the minor planet

Themis In Greek mythology and religion, Themis (; grc, Θέμις, Themis, justice, law, custom) is one of the twelve Titan children of Gaia and Uranus, and the second wife of Zeus. She is the goddess and personification of justice, divine order, fai ...

, whose perturbations by Jupiter eventually enabled him in 1873 (while at Helsinki Observatory) to determine the mass of the latter planet. He was awarded his doctorate by the University of Bonn in August 1854 for his dissertation titled "''De ascensionibus rectis, a Flamsteedio quadrantis muralis ope observatis''". In 1858 a

heliometer A heliometer (from Greek ἥλιος ''hḗlios'' "sun" and ''measure'') is an instrument originally designed for measuring the variation of the sun's diameter at different seasons of the year, but applied now to the modern form of the instrument ...

previously used by Friedrich Winnecke came into his hands, and was successfully employed in a series of parallax determinations. Krueger was made '' Privatdozent'' in the University in 1860. In 1862 Krueger was appointed Professor of Astronomy and Director of the Helsinki Observatory, working there for 14 years. At the time of his appointment he married Maria Wilhelmina Amalia, the eldest daughter of Friedrich Argelander. While in Helsinki, Krueger carefully determined the position of the stars of the

Double Cluster The Double Cluster (also known as Caldwell 14) consists of the open clusters NGC 869 and NGC 884 (often designated h Persei and χ (chi) Persei, respectively), which are close together in the constellation Perseus. Both visible with the ...

in Perseus. The large proper motion of the star Groombridge 34 was first detected by him. He also performed observations of

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as e ...

s, several comets and minor planets, in addition to his theoretical work. After leaving Helsinki, Krueger directed the

Gotha Gotha () is the fifth-largest city in Thuringia, Germany, west of Erfurt and east of Eisenach with a population of 44,000. The city is the capital of the Gotha (district), district of Gotha and was also a residence of the Ernestine House of Wet ...

Observatory (1876-1880), succeeding the recently deceased

Peter Andreas Hansen Peter Andreas Hansen (born 8 December 1795, Tønder, Schleswig, Denmark; died 28 March 1874, Gotha, Thuringia, Germany) was a Danish-born German astronomer. Biography The son of a goldsmith, Hansen learned the trade of a watchmaker at Flensburg, ...

. In Gotha he continued to record data for the

Astronomische Gesellschaft Katalog The ''Astronomische Gesellschaft Katalog'' (AGK) is an astrometric star catalogue. Compilation for the first version, AGK1, was started in 1861 by Friedrich Argelander and published between 1890 and 1954, listing 200 000 stars down to ninth m ...

, an astrometric star catalogue. Krueger was appointed as Director of the Royal Prussian Observatory in Kiel in 1880. In 1881, with the approval of the

Astronomical Society A list of notable groups devoted to promoting astronomy research and education. Africa * African Astronomical Society South Africa *Astronomical Society of Southern Africa Asia China * Chinese Astronomical Society India * Akash Mitra Mandal *A ...

(''Astronomische Gesellschaft''), Krueger became the editor of one of the foremost astronomical journals of the day, '' Astronomische Nachrichten''; following the death of the former editor Christian Peters the year before. Following the death of Krueger in 1896, the editorship passed to his former assistant and son-in-law

Heinrich Kreutz Heinrich Carl Friedrich Kreutz (September 8, 1854 – July 13, 1907) was a German astronomer, most notable for his studies of the orbits of several sungrazing comets, which revealed that they were all related objects, produced when a very lar ...

References

External links

Obituaries
listed in the

Astrophysics Data System The SAO/NASA Astrophysics Data System (ADS) is an online database of over 16 million astronomy and physics papers from both peer reviewed and non-peer reviewed sources. Abstracts are available free online for almost all articles, and full scanned ...

List of Adalbert Krueger's publications
in the Astrophysics Data System * Obituary printed in ''Astrophysical Journal'' * Obituary printed in ''Astronomical Journal'' {{DEFAULTSORT:Kruger, Adalbert 1832 births 1896 deaths People from the Province of Prussia 19th-century German astronomers People from Malbork