2011 MM4

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
Discovery [1]
Discovered byPan-STARRS 1
Discovery siteHaleakala Obs.
Discovery date24 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 arc6.99 yr (2,552 d)
Aphelion31.121 AU
Perihelion11.138 AU
21.129 AU
Eccentricity0.4729
97.12 yr (35,473 d)
49.176°
0° 0m 36.36s / day
Inclination100.48°
282.45°
6.86°
TJupiter−0.4
Physical characteristics
Mean diameter
64 km[3][5]
0.083[3][5]
9.5[1][2]

    Orbit and classification

    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]

    Retrograde centaur and damocloid

    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.

    Numbering and naming

    This minor planet has no number yet.

    Physical characteristics

    Diameter and albedo

    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.

    Rotation period

    As of 2018, no rotational lightcurve of has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown.[2][8]

    References
    1. "2011 MM4". Minor Planet Center. Retrieved 18 October 2018.
    2. "JPL Small-Body Database Browser: 2011 MM4" (2017-10-29 last obs.). Jet Propulsion Laboratory. Retrieved 18 October 2018.
    3. Johnston, Wm. Robert (7 October 2018). "List of Known Trans-Neptunian Objects". Johnston's Archive. Retrieved 17 October 2018.
    4. "List Of Centaurs and Scattered-Disk Objects". Minor Planet Center. Retrieved 18 October 2018.
    5. Bauer, James M.; Grav, Tommy; Blauvelt, Erin; Mainzer, A. K.; Masiero, Joseph R.; Stevenson, Rachel; et al. (August 2013). "Centaurs and Scattered Disk Objects in the Thermal Infrared: Analysis of WISE/NEOWISE Observations". The Astrophysical Journal. 773 (1): 11. arXiv:1306.1862. Bibcode:2013ApJ...773...22B. doi:10.1088/0004-637X/773/1/22.
    6. Peixinho, N.; Doressoundiram, A.; Delsanti, A.; Boehnhardt, H.; Barucci, M. A.; Belskaya, I. (October 2003). "Reopening the TNOs color controversy: Centaurs bimodality and TNOs unimodality". Astronomy and Astrophysics. 410: L29–L32. arXiv:astro-ph/0309428. Bibcode:2003A&A...410L..29P. doi:10.1051/0004-6361:20031420.
    7. de la Fuente Marcos, C.; de la Fuente Marcos, R. (August 2014). "Large retrograde Centaurs: visitors from the Oort cloud?". Astrophysics and Space Science. 352 (2): 409–419(Ap&SSHomepage). arXiv:1406.1450. Bibcode:2014Ap&SS.352..409D. doi:10.1007/s10509-014-1993-9.
    8. "LCDB Data for (342842)". Asteroid Lightcurve Database (LCDB). Retrieved 18 October 2018.

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