Johannes Franz Hartmann (January 11, 1865 – September 13, 1936) was a German physicist and astronomer. In 1904, while studying the spectroscopy of Delta Orionis he noticed that most of the spectrum had a shift, except the calcium lines, which he interpreted as indicating the presence of interstellar medium
He was the director of the Observatorio Astronómico de La Plata from November 1922 to May 1934. He oriented the work of the observatory towards astrophysics. He discovered three asteroids.
His doctorate was from the University of Leipzig in 1891 on lunar eclipses.
- ^ Asimov, Asimov's Biographical Encyclopedia of Science and Technology 2nd Revised edition
- ^ Hartmann, J. (1904). "Investigations on the spectrum and orbit of delta Orionis". Astrophysical Journal 19: 268–286. Bibcode:1904ApJ....19..268H. doi:10.1086/141112.
- ^ Hockey, Thomas (2009). The Biographical Encyclopedia of Astronomers. Springer Publishing. ISBN 978-0-387-31022-0. Retrieved August 22, 2012.