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Published December 10, 2004 | Submitted + Published
Journal Article Open

Discovery of a Candidate Inner Oort Cloud Planetoid


We report the discovery of the minor planet (90377) Sedna, the most distant object ever seen in the solar system. Prediscovery images from 2001, 2002, and 2003 have allowed us to refine the orbit sufficiently to conclude that Sedna is on a highly eccentric orbit that permanently resides well beyond the Kuiper Belt with a semimajor axis of 480 ± 40 AU and a perihelion of 76 ± 4 AU. Such an orbit is unexpected in our current understanding of the solar system but could be the result of scattering by a yet-to-be-discovered planet, perturbation by an anomalously close stellar encounter, or formation of the solar system within a cluster of stars. In all of these cases a significant additional population is likely present, and in the two most likely cases Sedna is best considered a member of the inner Oort Cloud, which then extends to much smaller semimajor axes than previously expected. Continued discovery and orbital characterization of objects in this inner Oort Cloud will verify the genesis of this unexpected population.

Additional Information

© 2004 American Astronomical Society. Receivved 2004 March 16; accepted 2004 April 21. We thank the staff at Palomar Observatory for their dedicated support of the robotic operation of the Samuel Oschin Telescope and the Palomar QUEST camera. We are grateful to D. Stern, A. Dey, S. Dawson, and H. Spinrad for obtaining critical follow-up observations at Keck Observatory and M. Schwartz of Tenagra Observatory for making his robotic telescope available for follow-up. We commend Project Pluto for making their fine ''orb_fit'' software freely usable by all. Re'em Sari has been inspirational in discussing scenarios of origin. This research is supported by a Presidential Early Career Award from NASA Planetary Astronomy.

Attached Files

Published - 0004-637X_617_1_645.pdf

Submitted - 0404456.pdf


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