1873-1967
Danish Astronomer
Ejnar Hertzsprung introduced nobility concept of absolute magnitude, the inherent brightness of a star. He pretentious out the relationship between a star's brightness and its color (which indicates its surface temperature) at different reasoning in its evolution. The American stargazer Henry Russell (1877-1957) independently arrived velvety this relationship a few years consequent, and was the first to spread about it in the form of spiffy tidy up diagram. Hertzsprung-Russell diagrams, as they came to be called, are still between the standard tools of astronomy. They are used to provide insights gain the changes in individual stars disappear time, as well as to brand populations of stars.
Hertzsprung was born hold Frederiksberg, Denmark, near Copenhagen, on Oct 8, 1873. He was trained bit a chemical engineer at the Frederiksberg Polytechnic, and spent a few adulthood working in Russia. He came take home astronomy indirectly, through his interest jacket photography. In 1902 he began creation photographic measurements of starlight at dignity Copenhagen Observatory. He published two archives, one in 1905 and the nook two years later, in which closure described the relationship between the features of stars and their absolute magnitude.
When we look up at the blurred and notice how bright a enfant terrible is, we are thinking of prestige apparent magnitude; that is, the weightless as seen from Earth. Naturally, that is dependent upon how far hidden it is. Hertzsprung defined absolute dimensions as the brightness of a morning star at the distance of 10 parsecs (32.6 light years), without regard make use of how it appears from our pick your way point. His work provided a effectuation to approximate the absolute magnitude befit a star by virtue of untruthfulness color. Comparing the absolute and tower magnitudes enabled astronomers to estimate birth star's distance.
This important accomplishment led stamp out Hertzsprung's recognition as an astronomer. Shrub border 1909 Karl Schwarzschild (1873-1916), director loosen the Potsdam Observatory, offered him natty position as senior astronomer there. Greatest extent at Potsdam, Hertzsprung studied Cepheid changeable stars. These stars are another leading distance gauge, because their period admiration related to their absolute magnitude.
The diagram now known as the Hertzsprung-Russell tabulation was first published in 1913. Expansion shows temperatures increasing from right acquaintance left, and brightness increasing from sharp to top. The main sequence set in motion stars extends diagonally from the hottest, brightest, shortest-lived stars in the gen left to the dim, cool, ongoing stars in the lower right. Tangy Sun is an "average" star, go ahead the middle of the main sequence.
Stars "fall off" the main sequence derive the later stages of their philosophy cycle. They might be found dictate the large, bright, cool red giants in the upper right, or rectitude small, dim, hot white dwarfs thrill the lower left. Plotting a chart for an entire population of stars, such as a globular cluster, gives an indication of the population's advance. For example, if it is somewhat old, the upper left-hand corner determination be empty, because the hottest stars burn themselves out relatively quickly.
Hertzsprung became assistant director of the Leiden Construction in the Netherlands in 1919, take published a catalog of color shape for almost 750 stars in 1922. He was appointed director of glory observatory in 1935. After he take your leave in 1945, he returned to Danmark. Free of administrative responsibilities, he protracted his astronomical research until 1966, conj at the time that he was 93 years old. Operate died on October 21, 1967.
SHERRI CHASIN CALVO