Biographies

Walter S. Adams and spectroscopy

Walter S. Adams and spectroscopy

Walter Sydney Adams was an astronomer who specialized in stellar spectroscopy. For 23 years he was director of the prestigious Monte Wilson Observatory.

He was born on December 20, 1876 in Kessab, near Antioquia, Syria. Son of missionaries, his family returned to the United States in 1898.

He studied and graduated from Dartmouth College where, in addition, he took the only astronomy course offered. He subsequently studied a master's degree in arts at the University of Chicago and Law in Pomona, graduating in 1926. He moved to Germany for a year to do other studies.

In 1901 Walter Sydney Adams became George Hale's assistant at the Yerkes Observatory. With Hale he later moved to the new observatory of Mount Wilson in 1904. He was assistant director from 1913 to 1923, in this year he was appointed director, a position he held until 1946.

His first works focused on the study of solar spectroscopy studying sunspots and solar rotation. Later he entered the study of stellar spectroscopy where he obtained his greatest successes and recognitions.

He found the difference between giant and dwarf stars with the use of the dark lines of their stellar spectra. Adams showed that it was possible to determine the luminosity and intrinsic brightness of a star by studying its spectrum. He described the method of spectroscopic parallax to determine the distance to the stars. He demonstrated the presence of carbon dioxide on the surface of Venus.

Walter Adams examined Sirius' companion and obtained his spectrum in 1915 determining that it was much hotter than the sun; He also deduced that, being so hot and being located at a distance of 8 light-years, it should be clearly visible and that it was not because it had a very small size with a great density, in this way he described the first white dwarf.

In 1925 he discovered that the light of these stars has a slight deviation from red due to high gravity, which is one of the confirmatory tests of the theory of general relativity.

Walter Sydney Adams died on May 11, 1956 in Pasadena, California. In his honor he named a minor planet and also a lunar crater.

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