Brouwer Award for Ortwin Gerhard

June 30, 2017

The Division on Dynamical Astronomy (DDA) of the American Astronomical Society has named Dr. Ortwin Gerhard from the Max Planck Institute for Extraterrestrial Physics (MPE) as the 2017 recipient of its Dirk Brouwer Award. Gerhard receives the distinction for his achievements in modelling the inner Milky Way galaxy.

The inner Galaxy is not only obscured by dust in the disk plane, but we also view it in projection from our location within the outer disk. In order to unravel the inner structure, Ortwin Gerhard and his group have utilized data from many wavebands and combined them “with increasingly sophisticated modelling techniques” to build a picture of a barred disk galaxy, in which the inner bar is the box/peanut structure visible in infrared surveys (see MPE Press Release: The inside of our Milky Way in 3D).

The image shows the top view of the current best model for the Milky Way. Dotted lines originating from the Sun (the circled dot) indicate sightlines through the central bulge, the bar, and the inner disk of the Milky Way. The Sun is located in the outer disk at approximately 8.2 kpc distance from the centre.

The committee stresses that the picture of the inner Galaxy established by Gerhard’s group is cosmologically important because it establishes that baryons are completely dominant in the inner part of our fairly typical Galaxy. His team not only made use of N-body simulations, they also developed and used the made-to-measure method (aka NMAGIC) for tailoring N-body simulations to match observational data.

Gerhard was a major player in the planetary nebula project, which extended our knowledge of the dynamics of elliptical galaxies to the largest scales yet probed. His collaborative studies of planetary nebulae in clusters of galaxies led to the first measurements of the motions of the intracluster stars in the Virgo and Coma clusters, and therefore to insights into the processes by which the diffuse intracluster light is produced.

First in Heidelberg, then in Basel and finally at the MPE in Garching, Ortwin Gerhard has built “research groups of international standing, wherein he has fostered a strong and coherent research programme that involves graduate students and postdocs”. Several of his former students and postdocs are now leaders in Galactic Dynamics in their own right. His international service to the astronomical community includes his service as President of IAU Division VII and as Vice-President and President of IAU Commission 33.

For his contributions to understanding the dynamics and structure of the inner Milky Way as well as more distant elliptical galaxies and clusters the DDA honours Ortwin Gerhard now with the Dirk Brouwer Award, which was established in 1976 to recognize outstanding contributions to the field of Dynamical Astronomy, including celestial mechanics, solar system dynamics, planetary and exo-planetary dynamics, astrometry, geophysics, stellar systems, galactic and extra galactic dynamics. The main criteria, which are not necessarily weighted equally, are (a) excellence in scientific research; (b) impact and influence in the field; (c) excellence in teaching and training of students; (d) outstanding advancement and other support of the field through administration, public service or engineering achievement. Ortwin Gerhard will deliver an invited lecture at the 2018 DDA Meeting.


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