Holmberg, Erik Bertil (1908–2000)
Swedish astronomer known for his studies of external galaxies. In 1941 he
published the results of a remarkable simulation to study the effects of
interacting galaxies. His experiment consisted of an array of light bulbs
to represent, by their location, the stellar distribution in a galaxy and,
by their brightness, the local strength of gravity. Using photocells he
measured the simulated gravitational forces as, step by step, two galaxies
passed close to each other. One of his conclusions was that interacting
galaxies often merge into a single larger galaxy. But it was not for another
three decades, when fast enough computers became available, that his results
could be confirmed. In the late 1940s, he began developing standards for
measuring galaxy magnitudes from photographic plates, including the Holmberg
radius. His work was published in a large catalogue of galaxies that
has been widely used in extragalactic research, notably in statistical studies
of the space density of different types of galaxies. Holmberg found a correlation
between galaxy magnitudes and colors, the Holmberg relation,
and helped show that elliptical galaxies are generally older than spirals.
Related entry
• galaxy
interaction
Related category
• ASTRONOMERS
AND ASTROPHYSICISTS
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