90482 Orcus
From Freepedia
| Discovery A | |
|---|---|
| Discoverer | M. Brown, C. Trujillo, D. Rabinowitz |
| Discovery date | February 17, 2004 |
| Alternate designations | 2004 DW B |
| Category | Plutino |
| Orbital elements C | |
| Eccentricity (e) | 0.218 |
| Semi-major axis (a) | 5903.997 Gm (39.466 AU) |
| Perihelion (q) | 4616.704 Gm (30.861 AU) |
| Aphelion (Q) | 7191.291 Gm (48.071 AU) |
| Orbital period (P) | 90558.570 d (247.94 a) |
| Mean orbital speed | 4.68 km/s |
| Inclination (i) | 20.559° |
| Longitude of the ascending node (Ω) | 268.556° |
| Argument of perihelion (ω) | 73.231° |
| Mean anomaly (M) | 158.056° |
| Physical characteristics | |
| Dimensions | 840 - 1880 km |
| Mass | 6.2 - 70×1020 kg |
| Density | 2.0? g/cm³ |
| Surface gravity | 0.2348 - 0.5254 m/s² |
| Escape velocity | 0.4441 - 0.9939 km/s |
| Rotation period | ? d |
| Spectral class | ? |
| Absolute magnitude | 2.3 |
| Albedo | 0.09 |
| Mean surface temperature | ~45 K |
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.
Size and magnitude
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 2003 UB313, Pluto, 2005 FY9, 2003 EL61 and 90377 Sedna.
Name
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.
External links and sources
- 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
… | Previous asteroid | 90482 Orcus | Next asteroid | …
| Large trans-Neptunian objectsedit |
| Kuiper belt: Pluto (Charon) | Orcus | Ixion | 2002 UX25 | Varuna 2002 TX300 | 2003 EL61 | Quaoar | 2005 FY9 | 2002 AW197 |
| Scattered disc: 2003 UB313 | Sedna† |
| See also Triton, astronomical objects and the solar system's list of objects, sorted by radius or mass. For pronunciation, see: Centaur and TNO pronunciation. † Current MPC classification. Some consider Sedna an Oort cloud object. |
| The minor planetsedit |
| Vulcanoids | Main belt | Groups and families | Near-Earth objects | Jupiter Trojans |
| Centaurs | Damocloids | Comets | Trans-Neptunians (Kuiper belt | Scattered disc | Oort cloud) |
| For other objects and regions, see: Binary asteroids, Asteroid moons and the Solar system For a complete listing, see: List of asteroids. For pronunciation, see: Pronunciation of asteroid names. |
