| Discovery [1] | |
|---|---|
| Discovered by | Pan-STARRS 1 |
| Discovery site | Haleakala Obs. |
| Discovery date | 24 June 2011 |
| Designations | |
| 2011 MM4 | |
| 2011 MM4 | |
| centaur [2] [3] [4] · damocloid distant [1] | |
| Orbital characteristics [2] | |
| Epoch 23 March 2018 (JD 2458200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 6.99 yr (2,552 d) |
| Aphelion | 31.121 AU |
| Perihelion | 11.138 AU |
| 21.129 AU | |
| Eccentricity | 0.4729 |
| 97.12 yr (35,473 d) | |
| 49.176° | |
| 0° 0m 36.36s / day | |
| Inclination | 100.48° |
| 282.45° | |
| 6.86° | |
| TJupiter | −0.4 |
| Physical characteristics | |
| 64 km [3] [5] | |
| 0.083 [3] [5] | |
| 9.5 [1] [2] | |
2011 MM4, provisional designation : 2011 MM4, is a sizable centaur and retrograde damocloid from the outer Solar System, approximately 64 kilometers (40 miles) in diameter. It was discovered on 24 June 2011, by astronomers with the Pan-STARRS 1 at the Haleakala Obs. in Hawaii. [1] [3]
2011 MM4 orbits the Sun at a distance of 11.1–31.2 AU once every 97 years and 2 months (35,473 days; semi-major axis of 21.13 AU). Its orbit has an eccentricity of 0.47 and an inclination of 100° with respect to the ecliptic. [2] The body's observation arc begins at Pan-STARRS in June 2010. [1]
2011 MM4 is a member of the centaurs, a population of inward-moving bodies transiting from the Kuiper belt to the group of Jupiter-family comets. Orbiting mainly between Jupiter and Neptune, they typically have a semi-major axis of 5.5 to 30.1 AU. Centaurs are cometary-like bodies with an eccentric orbit. Their short dynamical lifetime is due to the perturbing forces exerted on them by the outer planets of the Solar System. [6]
The object is on a retrograde orbit as it has an inclination of more than 90°. [2] [7] There are only about a hundred known retrograde minor planets out of nearly 800,000 observed bodies, and, together with 2013 LU28 and 2008 YB3 , it is among the largest such objects. [7] The object also meets the orbital definition for being a damocloid. This is a small group of cometary-like objects without a coma or tail and a Tisserand's parameter with respect to Jupiter of less than 2 besides a retrograde orbit.
As of 2025 [update] , 2011 MM4 has not been numbered or named by the Minor Planet Center.
According to the survey of centaurs and scattered-disk objects carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, 2011 MM4 measures 64 kilometers in diameter and its surface has an albedo of 0.083, [5] which makes it too small to be considered as a dwarf-planet candidate.
As of 2021 [update] , no rotational lightcurve of has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown. [2] [8]