Ejnar Hertzsprung
Encyclopedia
Ejnar Hertzsprung was a Danish
chemist
and astronomer
.
Hertzsprung was born in Copenhagen
. In the period 1911–1913, together with Henry Norris Russell
, he developed the Hertzsprung–Russell diagram
.
In 1913 he determined the distances to several Cepheid variable stars by statistical parallax
, and was thus able to calibrate the relationship discovered by Henrietta Leavitt between Cepheid period and luminosity
. In this determination he made a mistake, possibly a slip of the pen, putting the stars 10 times too close. He used this relationship to estimate the distance to the Small Magellanic Cloud
.
From 1919 to 1946 Hertzsprung worked at Leiden Observatory
in The Netherlands, from 1937 as director.
Perhaps his greatest contribution to astronomy was the development of a classification system for stars to divide them by spectral type, stage in their development, and luminosity. The so-called "Hertzsprung–Russell Diagram" has been used ever since as a classification system to explain stellar types and evolution.
He discovered two asteroid
s, one of which is the Amor asteroid
1627 Ivar
.
Hertzsprung died in Roskilde
in 1967.
Named after him
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
chemist
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
and astronomer
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
.
Hertzsprung was born in Copenhagen
Copenhagen
Copenhagen is the capital and largest city of Denmark, with an urban population of 1,199,224 and a metropolitan population of 1,930,260 . With the completion of the transnational Øresund Bridge in 2000, Copenhagen has become the centre of the increasingly integrating Øresund Region...
. In the period 1911–1913, together with Henry Norris Russell
Henry Norris Russell
Henry Norris Russell was an American astronomer who, along with Ejnar Hertzsprung, developed the Hertzsprung–Russell diagram . In 1923, working with Frederick Saunders, he developed Russell–Saunders coupling which is also known as LS coupling.-Biography:Russell was born in 1877 in Oyster Bay, New...
, he developed the Hertzsprung–Russell diagram
Hertzsprung–Russell diagram
The Hertzsprung–Russell diagram is a scatter graph of stars showing the relationship between the stars' absolute magnitudes or luminosities versus their spectral types or classifications and effective temperatures. Hertzsprung–Russell diagrams are not pictures or maps of the locations of the stars...
.
In 1913 he determined the distances to several Cepheid variable stars by statistical parallax
Parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. The term is derived from the Greek παράλλαξις , meaning "alteration"...
, and was thus able to calibrate the relationship discovered by Henrietta Leavitt between Cepheid period and luminosity
Luminosity
Luminosity is a measurement of brightness.-In photometry and color imaging:In photometry, luminosity is sometimes incorrectly used to refer to luminance, which is the density of luminous intensity in a given direction. The SI unit for luminance is candela per square metre.The luminosity function...
. In this determination he made a mistake, possibly a slip of the pen, putting the stars 10 times too close. He used this relationship to estimate the distance to the Small Magellanic Cloud
Small Magellanic Cloud
The Small Magellanic Cloud is a dwarf galaxy. It has a diameter of about 7,000 light-years and contains several hundred million stars. It has a total mass of approximately 7 billion times the mass of our Sun....
.
From 1919 to 1946 Hertzsprung worked at Leiden Observatory
Leiden Observatory
Leiden Observatory is an astronomical observatory in the city of Leiden, Netherlands. It was established by Leiden University in 1633, to house the quadrant of Snellius, and is the oldest operating University observatory in the world Leiden Observatory (Sterrewacht Leiden in Dutch) is an...
in The Netherlands, from 1937 as director.
Perhaps his greatest contribution to astronomy was the development of a classification system for stars to divide them by spectral type, stage in their development, and luminosity. The so-called "Hertzsprung–Russell Diagram" has been used ever since as a classification system to explain stellar types and evolution.
He discovered two asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...
s, one of which is the Amor asteroid
Amor asteroid
The Amor asteroids are a group of near-Earth asteroids named after the asteroid 1221 Amor. They approach the orbit of the Earth from beyond, but do not cross it. Most Amors do cross the orbit of Mars...
1627 Ivar
1627 Ivar
1627 Ivar is a large Mars-crosser asteroid that was discovered in 1929 by Ejnar Hertzsprung at the Union Observatory in Johannesburg, South Africa...
.
Hertzsprung died in Roskilde
Roskilde
Roskilde is the main city in Roskilde Municipality, Denmark on the island of Zealand. It is an ancient city, dating from the Viking Age and is a member of the Most Ancient European Towns Network....
in 1967.
Honors
Awards- Gold Medal of the Royal Astronomical SocietyGold Medal of the Royal Astronomical Society-History:In the early years, more than one medal was often awarded in a year, but by 1833 only one medal was being awarded per year. This caused a problem when Neptune was discovered in 1846, because many felt an award should jointly be made to John Couch Adams and Urbain Le Verrier...
in 1929 - Bruce MedalBruce MedalThe Catherine Wolfe Bruce Gold Medal is awarded every year by the Astronomical Society of the Pacific for outstanding lifetime contributions to astronomy. It is named after Catherine Wolfe Bruce, an American patroness of astronomy, and was first awarded in 1898...
in 1937
Named after him
- Hertzsprung (crater)Hertzsprung (crater)Hertzsprung is an enormous lunar crater that is located on the far side of the Moon, beyond the western limb. In dimension, this formation is larger than several of the lunar mare areas on the near side. It lies in the northwestern fringe of the blast radius of the Mare Orientale impact basin...
on the Moon - AsteroidAsteroidAsteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...
1693 Hertzsprung1693 Hertzsprung1693 Hertzsprung is a main-belt asteroid discovered on May 5, 1935 by Van Gent, H. at Johannesburg .- External links :*...
Sources
- Sky & Telescope, January, 1968, Sky Publishing Corporation, Cambridge