Submitting Campus

Daytona Beach


Physical Sciences

Document Type


Publication/Presentation Date



Using the deepest and finest resolution images of the universe acquired with the Hubble Space Telescope and a similar image taken 7 yr later for the Great Observatories Origins Deep Survey, we have derived proper motions for the point sources in the Hubble Deep Field–North. Two faint blue objects, HDF 2234 and HDF 3072, are found to display significant proper motion, 10:0 ± 2:5 and 15:5 ± 3:8 mas yr¯1. Photometric distances and tangential velocities for these stars are consistent with disk white dwarfs located at ~500 pc. The faint blue objects analyzed by Ibata et al. and Mendez & Minniti do not show any significant proper motion; they are not halo white dwarfs, and they do not contribute to the Galactic dark matter. These objects are likely to be distant active galactic nuclei.

Publication Title

The Astrophysical Journal


Institute of Physics Publishing, Inc.

Grant or Award Name

National Science Foundation grant 0307315

Additional Information

Dr. von Hippel was not affiliated with Embry-Riddle Aeronautical University at the time this paper was published.