Erik Bertil Holmberg

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Erik Bertil Holmberg (born November 13, 1908 in Tofteryd , † March 2, 2000 in Partille ) was a Swedish astronomer .


He received his doctorate in 1937 at Lund University for an investigation of double and multiple galaxies under the guidance of Knut Lundmark . He was a professor at the Lund Observatory and later Professor and Director at the Astronomical Observatory at Uppsala University .

Scientific work

He became known for his studies of the interaction of galaxies . As early as 1941, he simulated the gravitational forces that arise when two galaxies interact. To do this, he used an arrangement of incandescent lamps , which in their arrangement represent the distribution of the galaxies and with their brightness the respective local strength of the gravitational field . With the help of photocells , he was able to measure the encounter between two galaxies and found out that two galaxies that meet each other often merge into one large galaxy. However, his results could only be confirmed about 20 years later, when the computers were good enough to calculate such interactions.

Later he dealt with the evaluation of observation data (measurement of the brightness of galaxies) and defined the Holmberg radius named after him . With this value it is possible to estimate the radius of a galaxy independent of its orientation in space. The radius is measured at which the surface brightness is 26.5 magnitudes per square arc second (measured in the blue wavelength range of visible light ). Holmberg also found a relationship between the brightness of a galaxy and its color ( Holmberg relationship ) and showed that elliptical galaxies are generally older than spiral galaxies .

See also

Holmberg catalog

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