90482 Orcus
90482 Orcus (originally known by the provisional designation 2004 DW) is a Kuiper Belt object (KBO) that was discovered by Michael Brown of Caltech, Chad Trujillo of the Gemini Observatory, and David Rabinowitz of Yale University. The discovery images of this object were acquired on February 17, 2004. Precovery images as early as November 8, 1951 were later identified.
The
apparent magnitude of the object is 18.5, which is the same brightness as
50000 Quaoar. The orbit indicates that the object is a
Plutino. Therefore, the object is probably larger than Quaoar, since it is farther from the
Sun. Using an assumed
albedo of 0.09, Trujillo estimates its diameter to be approximately 1600 km, which makes Orcus the sixth-largest discovered KBO, after ,
Pluto, , and
90377 Sedna.
Since it shares a similar size and
orbit to that of
Pluto, it too must be named after a deity of the
underworld. In accordance with
International Astronomical Union astronomical naming conventions, the discoverers' suggested name of
Orcus was approved and published
November 22,
2004. Orcus is both another name for the Greek deity
Hades and a separate god of the dead in
Roman mythology.
*
MPEC 2004-D09 announcing the discovery but attributing it to
Raymond J. Bambery,
Steven H. Pravdo,
Michael D. Hicks,
Kenneth J. Lawrence,
Daniel MacDonald,
Eleanor F. Helin and
Robert Thicksten /
NEAT*
MPEC 2004-D13 correcting MPEC 2004-D09
*
Chad Trujillo's page on 2004 DW*
First BBC article*
First New Scientist article
