(90482) Orcus and Vanth

compiled by Wm. Robert Johnston
last updated 11 April 2010

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: 39.301 AU
orbital period P: 246.38 y (=89,991.0 d)
eccentricity e: 0.22248
perihelion distance q: 30.557 AU
aphelion distance Q: 48.044 AU
inclination i: 20.59398°
argument of perihelion omega: 72.41°
ascending node OMEGA: 268.7244°
mean anomaly M: 162.48°
perihelion passage TP: 1896-01-26.7
Epoch: 10 APR 2007
data arc: 1951-2004 (112 obs.)

orbital data, secondary:
semimajor axis a: 8,980 ± 23 km [B09a]
semimajor axis/primary radius a/Rp: (19?)
orbital period P: 9.5393±0.0001 d [B09a]
eccentricity e: 0.002; <0.0036 [B09a]
inclination i: 90.2° ± 0.6° [B09a]
ascending node OMEGA: 50.0° ± 0.6° [B09a]
mean anomaly M: 143.1° ± 0.02° [B09a]
epoch: JD 2454439.280 [B09a]

other data, primary:
diameter: 946 +74/-72 km [S07a] (combined)
940±70 km [B09a] (combined)
820-900 km [B09a]
absolute magnitude H: 2.27±0.03 [D05b]
rotation period: (13.18841±0.00111 h) [R07a]
amplitude delta M: 0.04 ± 0.02 [O05a]
0.18 ± 0.08 [R07a]
color index B-V: 0.68±0.04 [D05b]
color index V-R: 0.37±0.04 [D05b]
color index V-I: 0.74±0.04 [D05b]
color index V-J: 1.08±0.04 [D05b]
color index V-H: 1.21±0.05 [D05b]
slope parameter G: (0.15) assumed
geometric albedo: 0.197 +0.034/-0.028 [S07a];
0.28±0.04 [B09a]
mass: (6.32±0.01)x1020 kg [B09a]
density: 1.45±0.3 g cm-3 [B09a];
1.5-1.6 g cm-3 [B09a]
type: ?

other data, secondary:
diameter: (262 ± 170 km);
280-640 km [B09a]
diameter ratio Ds/Dp: (0.29 ± 0.17)
absolute magnitude H: 4.88±0.05 [B09a]
component magnitude difference: 2.54±0.01 (F606W) [B09a];
(2.61±0.07) (V) [B09a]
rotation period: ?

--(90482) Orcus--discovery and notes:

Primary discovered 17 February 2004 by M. Brown, C. Trujillo, and D. Rabinowitz from Palomar Observatory, California, USA. Linked to prediscovery observations from 8 November 1951. Alternate designation 2004 DW.

Companion discovered by M. E. Brown and T.-A. Suer using Hubble Space Telescope observations from 13 November 2005; reported 22 February 2007. The name Vanth was assigned April 2010.

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

--Links, more technical:

--Links, less technical:

--Links to ADS abstracts:


© 2007-2009, 2010 by Wm. Robert Johnston.
Last modified 11 April 2010.
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