Nessus is a centaur, a dynamically unstable population of minor planets between the classical asteroids and the trans-Neptunian objects. It orbits the Sun at a distance of 11.9–37.4 AU once every 122 years and 4 months (44,670 days; semi-major axis of 24.64 AU). Its orbit has an eccentricity of 0.52 and an inclination of 16° with respect to the ecliptic. At its perihelion (11.9 AU), it moves much closer to the Sun than Uranus (19.2 AU) but not as close as Saturn (9.6 AU), while at its aphelion (37.4 AU), it moves out well beyond the orbit of Neptune (30.1 AU).[4]
The orbits of centaurs are unstable due to perturbations by the giant planets. Nessus is an "SE object" because currently Saturn controls its perihelion and its aphelion is within the Kuiper belt. It is estimated to have a relatively long orbital half-life of about 4.9 million years.[15] Fifty clones of the orbit of Nessus suggest that it will not pass within 1 AU (or 150 million kilometers) of any planet for at least 20,000 years.[16]
A symbol derived from that for 2060 Chiron, U+2BDC⯜NESSUS (), was devised in the late 1990s by German astrologer Robert von Heeren. It replaces Chiron's K with an N for Nessus.[19]
As of 2018, no rotational lightcurve of Nessus has been obtained from photometric observations. However, a brightness variation of 0.5 magnitude was measured in the 1990s, indicating that the body has a non-spherical, elongated shape.[14] The body's rotation period and pole remain unknown.[4][13]
Diameter and albedo
According to the Herschel Space Observatory with its PACS instrument, Nessus measures 57 kilometers in diameter and its surface has an albedo of 0.086,[8] while infrared observations with the Spitzer Space Telescope gave a diameter of 60 kilometers with an albedo of 0.065.[9] The Collaborative Asteroid Lightcurve Link assumes a carbonaceous standard albedo of 0.057 and derives a diameter of 68.48 kilometers based on an absolute magnitude of 9.55.[13]
In popular culture
Nessus is a playable destination in the 2017 video game Destiny 2, after previously being referenced in the series' 2014 debut entry Destiny. Known simply as "Nessus," it is described as a planetoid that has been terraformed by a cybernetic species known as the Vex into a "machine world."[23]
^ abcDuffard, R.; Pinilla-Alonso, N.; Santos-Sanz, P.; Vilenius, E.; Ortiz, J. L.; Mueller, T.; et al. (April 2014). ""TNOs are Cool": A survey of the trans-Neptunian region. XI. A Herschel-PACS view of 16 Centaurs". Astronomy and Astrophysics. 564: 17. arXiv:1309.0946. Bibcode:2014A&A...564A..92D. doi:10.1051/0004-6361/201322377. S2CID119177446.
^ abcJohn Stansberry; Will Grundy; Mike Brown; Dale Cruikshank; John Spencer; David Trilling; Jean-Luc Margot (2007). Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope. arXiv:astro-ph/0702538. Bibcode:2008ssbn.book..161S.
^ abcdeBelskaya, Irina N.; Barucci, Maria A.; Fulchignoni, Marcello; Dovgopol, Anatolij N. (April 2015). "Updated taxonomy of trans-neptunian objects and centaurs: Influence of albedo". Icarus. 250: 482–491. Bibcode:2015Icar..250..482B. doi:10.1016/j.icarus.2014.12.004.
^"Asteroid (7066) Nessus" (Ephemeris at epoch 58447 MJD). AstDyS-2, Asteroids – Dynamic Site; Department of Mathematics, University of Pisa, Italy. Retrieved 26 November 2018.
^ abDavies, John K.; McBride, Neil; Ellison, Sara L.; Green, Simon F.; Ballantyne, David R. (August 1998). "Visible and Infrared Photometry of Six Centaurs". Icarus. 134 (2): 213–227. Bibcode:1998Icar..134..213D. doi:10.1006/icar.1998.5931.