Dr. Otto Franz (Emeritus)

Stellar Astronomy

PhD University of Vienna, 1955

Dr. Otto Franz was hired as an astronomer at Lowell in 1965 by Dr. John Hall, the Observatory’s fourth director. While he has at times in his career at Lowell carried out general stellar, extragalactic and solar system studies, his primary research focus has been on the investigation of the physical and dynamical properties of binary stars and stellar aggregates.

Dr. Franz is one of the first astronomers to use the Hubble Space Telescope (HST) for the study of binary stars. In 1972 he became involved, as a member of the Astrometry Instrument Definition Team, with what was to be the Large Space Telescope (LST) and later was built as the 90-inch HST. He was the first to propose to NASA a space telescope project involving positional and brightness measurements of the components of binary stars. His proposal specified work that couldn’t be carried out with ground-based telescopes.

His role as a Hubble team member ensured that the telescope would provide the capability of resolving and investigating binary stars of angular separation and magnitude previously inaccessible for study by any other means. Being granted observing time on the HST has always been highly competitive, but as a team member, Dr. Franz’s initial access to the telescope was guaranteed, subject to team consensus.

He is currently working on the completion of a nearly 20-year Hubble Space Telescope research project on faint, low-mass binary stars, which is being carried out by multiple institutions to calibrate the Mass-Luminosity Relation (MLR) for the least massive stars in existence (Mass-Luminosity Relation states that the luminosity of a star is proportional to some power of the mass of a star).