Vanth (moon)
- Michael E. Brown
- T.-A. Suer
Vanth is the first known moon of Plutinos and dwarf planet candidates ( 90482 ) Orcus. Due to its estimated size, it is probably part of a binary system.
Discovery and designation
Vanth was developed by Michael E. Brown and T.-A. Suer discovered in images from the Hubble Space Telescope on 13 November 2005. Vanth was at 0.25 arcsec distance from Orcus found a difference in the apparent brightness of 2.7 ± 1.0. The discovery was announced on 22 February 2007; the moon was given the provisional designation S/2005 ( 90482 ) 1
On 23 March 2009 Brown asked the readers of his weekly column to suggest a suitable name for the new moon to transmit the best of it on 5 April 2009 at the IAU. The name Vanth was selected from a wide range of proposals. Vanth was the only name that was purely Etruscan in origin. It was the most popular proposal, which was first described by Sonya Taafe.
On 7 April 2010, the moon of the International Astronomical Union ( IAU) was officially named after the Psychopompos Vanth, a demon in the Etruscan mythology that accompanied the souls of the dead to the underworld. Sometimes she wore scrolls on which the deeds of the deceased were recorded. Vanth appears on grave paintings and sarcophagi, where she is portrayed as a rule, with big wings, white robes, and a torch. It occurs occasionally as a juvenile accompanied by Charun, so Vanth is often associated with Charon, as Orcus (nicknamed the "anti- Pluto " because the orbital resonance with Neptune Orcus almost on the opposite side of the sun holds ) parallels to Pluto has.
Web properties
Vanth orbits Orcus an almost perfectly circular orbit at 8980 km average distance to the center ( 18.979 Orcusradien ). The orbital eccentricity is a maximum of 0.0036, the web is 90.20 ° (Other Information: 73 ° or 109 ° ) inclined to the ecliptic.
Vanth orbits Orcus in 9 days, 12 hours and 57 minutes, which in Orcus - year corresponds to approximately 9433.7 rounds (about 246.38 Earth years ).
Brown assumes that Orcus and Vanth as Pluto and Charon have a double bonded rotation, so always show each other the same page.
It is believed that the moon is probably a captured Kuiper belt object because it is not very similar to other " collision moons ". This would be influenced by the so-called Vanth Kozai effect, which means that the orbital inclination and eccentricity are coupled to each other ( the orbital inclination and the periapsis decreases when increasing the eccentricity, and vice versa). Since the almost circular path but rather speaks against a formation through a collision can not be excluded.
Physical Properties
One is of the same reflectivity and the same density as that of the central body, can assume a diameter of 262 km, which corresponds to about one quarter of the diameter of Orcus. Since Vanth is in contrast to Orcus colored more red, it is quite possible that the albedo by a factor of two is darker, which corresponds to a diameter of even 640 kilometers ( more than half the diameter of Orcus ).
Research
Since the discovery in 2005 Vanth could only be observed by ground-based telescopes, while its orbital elements are determined. The moon is too close to Orcus in order to determine the composition of its surface with ground-based telescopes can spectroscopically. When observed by the Hubble Space Telescope after all, could deviate from Orcus color can be found. In the infrared spectrum no absorption of water ice has been demonstrated, in contrast to Orcus.