Up for auction "Astronomer" Ira Sprague Bowen Hand Signed 3X5 Card.

ES-272A

Ira Sprague Bowen

(December 21, 1898 – February 6, 1973) was an American physicist and astronomer.

In 1927 he discovered that nebulium was not really a chemical

element but instead doubly ionized oxygen.  Bowen was born in Seneca Falls, New York in 1898 to Philinda

Sprague and James Bowen. Due to frequent moves of his family he was home

schooled until the death of his father in 1908. From that point on he attended

the Houghton College where his mother worked as

teacher. After graduation from high school in 1915 Bowen stayed at the junior

college of Houghton College and later joined Oberlin

College from which he graduated in 1919. During the time at Oberlin

College Bowen did some research on the properties of steel together with the

scientist Robert Hadfield. The results were published in

1921. Bowen started studying physics at

the University of Chicago in fall 1919.

Already in 1921 Bowen took a position in the research group of Robert Andrews Millikan. He was assigned

to do ultraviolet spectroscopy of chemical elements. Millikan was persuaded by George Ellery Hale to move to the California Institute of Technology

in 1921 and Bowen moved with him. The contact with Hale enabled Bowen also to

work at the Mount Wilson Observatory and the Palomar Observatory. Bowen gave lectures on

general physics at Caltech and did research on cosmic rays and followed his

studies on UV spectroscopy. He also did calculations on spectra for the light

elements of the periodic table. With that data and the inspiration from a

chapter on gaseous nebula and the emission of radiation at low density in the

book Astronomy by Henry Norris Russell, Raymond Smith Dugan and John Quincy Stewart he achieved his best known

discovery. The green emission lines of the Cat's Eye Nebula

at 4959 and 5007 Ångström were discovered by William

Huggins in 1864. Because no known element was showing these emission

lines in the experiment it was concluded in the late 1890s that a new element

was responsible for that lines, it was called nebulium.

Bowen was able to calculate the forbidden transitions of doubly ionized oxygen to be exactly where

the lines had been found. The low probability for collisions in the nebula made

it impossible for the oxygen to get from the excited stated to the ground state

and so the forbidden transitions were the main path for the relaxation. Bowen

published his findings in 1927 and concluded that nebulium was not really a chemical

element. Bowen was the first director of the Palomar Observatory, serving from 1948 to 1964.

Before his retirement in 1964 and even afterwards Bowen was involved in the improvement

of the optical design of several large optical instruments, for example the

100 inch Irenee duPont at the Las Campanas Observatory. He is also known

in the context of meteorology for the introduction of the Bowen ratio,

which quantifies the ratio of sensible to latent heat over an evaporating

surface.