Astronomer and former Hubble Fellow Scott Sheppard is the newest member of DTM’s Research Staff. Sheppard’s research focuses on observations of small, primordial bodies in our Solar System and planetary systems around other stars and what those observations imply for theories of planetary system formation. Sheppard completed his Ph.D. at the University of Hawaii’s Institute for Astronomy in 2004, was a Hubble Fellow at DTM from 2004 to 2007, and joined the Research Staff on 1 July.

Sheppard produced the first large sampling of light curves for Kuiper Belt Objects (KBOs). A third of the objects he observed exhibited variability at sufficiently short periods to imply that these objects are rubble piles lacking internal strength, a result suggesting that collisions were frequent at some stage of Kuiper Belt history. He discovered the first contact binary KBO, which points to capture and progressive in-spiralling by tidal friction as earlier theory by others had suggested. The discovery also yielded the first measurement of the density of a KBO, with a sufficiently low value (near 1 g/cm³) to indicate a porous structure.

Sheppard and colleagues carried out systematic surveys to detect and characterize the small irregular satellites of the giant planets, objects that were captured by their primary early in Solar System history. He is the discoverer or co-discoverer of more than one third of the 163 known Solar System satellites. He showed further that Jovian irregular satellites belong to families that can be traced to a single parent that was captured by Jupiter and later disrupted, a result that constrains the number of objects available for capture and the energy of subsequent collisions.

Sheppard and his colleague Chad Trujillo discovered three Neptune Trojans, asteroids sharing the planet’s semimajor axis but leading or following it by 60°. That one of the Neptune Trojans has a high inclination implies that the body was dynamically excited, that the Neptune Trojans occupy a thick cloud, and that they constitute a population of primitive objects having many parallels with the Jupiter Trojans.

For more information on Sheppard’s research, see his Web site and publications.