(136199) Eris and Dysnomia
(=2003 UB313)

compiled by Wm. Robert Johnston
last updated 30 December 2008

Orbital elements and other data (Assumed or derived values in parenthesis, my estimates in italics and parenthesis. Source identifications in brackets, see this link for sources):

orbital data, primary (osculating elements) [JPL]:
semimajor axis a: 67.732 AU
orbital period P: 557.4 y (=203,603 d)
eccentricity e: 0.4400
perihelion distance q: 37.93 AU
aphelion distance Q: 97.53 AU
inclination i: 44.1595°
argument of perihelion omega: 151.56°
ascending node OMEGA: 35.8844°
mean anomaly M: 197.96°
perihelion passage TP: 2258-03-06
Epoch: 10 APR 2007
data arc: 1954-2006 (195 obs.)

orbital data, secondary:
semimajor axis a: 37,430 ± 140 km [B07a]
semimajor axis/primary radius a/Rp: (24?)
orbital period P: 15.772 ± 0.002 d [B07a]
eccentricity e: <0.010 [B07a]
inclination i: 61.3°±0.7° or 142°±3° [B07a]

other data, primary:
diameter: 3,000 ± 400 km [B06a]
2,400 ± 100 km [B06b]
2,657 +216/-208 [S07a]
absolute magnitude H: -1.17 ± 0.36 [JPL]
-1.12 ± 0.01 [B06b]
rotation period: 1.08 ± 0.02 d? [R08a]
amplitude delta M: 0.1? [R08a]
color index B-V: (0.71) [B05d]
color index V-R: (0.45) [B05d]
color index R-I: (0.33) [B05d]
color index R-J: (0.56) [B05d]
color index J-H: (-0.29) [B05d]
color index H-K: (-0.40) [B05d]
slope parameter G: (0.15) assumed
geometric albedo: 0.60 ± 0.15 [B06a]
0.87 ± 0.07 [B06b]
0.689 +0.122/-0.010 [S07a]
mass: (1.66±0.02) x 1022 kg [B07a]
(0.0027 ME)
density: 2.26 ± 0.25 g/cm3 [G06a]
type: ?

other data, secondary:
diameter: (350-490 km?)
diameter ratio Ds/Dp: (0.13?)
component magnitude difference: 4.43 ± 0.05 [I8600]
rotation period: ?

--(136199) Eris--discovery and notes:

Primary discovered 21 October 2003 by M. E. Brown, C. A. Trujillo, and D. Rabinowitz from Palomar Observatory, announced 2005 with provisional designation 2003 UB313. Linked to observations from 1954. Permanent number assigned 7 September 2006, name assigned 14 September 2006.

Companion discovered by M. E. Brown et al. by observations from the Keck II adaptive optics telescope made 10 September 2005; announced 1 October 2005. Name assigned 14 September 2006.

Eris had been nicknamed "Xena" by the discovery team, who had also nicknamed the satellite "Gabrielle".

See more information and links at Asteroid/Comet Connection Catchall Catalog page

--Links, more technical:

--Links, less technical:

--Links to ADS abstracts:


© 2005-2007, 2008 by Wm. Robert Johnston.
Last modified 30 December 2008.
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