2015 XX169

2015 XX169
Discovery
Discovered by Mount Lemmon Srvy.
Discovery site Mount Lemmon Obs.
Discovery date 9 December 2015
Designations
MPC designation 2015 XX169
Apollo,[1][2]
Earth crosser
Orbital characteristics[2]
Epoch February 16, 2017 (JD 2457800.5)
Uncertainty parameter 1
Observation arc 363 days
Aphelion 1.18545 AU
Perihelion 0.81648 AU
1.00097 AU
Eccentricity 0.18431
1.00149 y (365.79 d)
345.528°
Inclination 7.640°
256.630°
283.587°
Earth MOID 0.0154 AU
Physical characteristics
Dimensions 9–22 m[a][3]
27.4[2]

    2015 XX169 (also written 2015 XX169) is an Apollo asteroid that is a temporary horseshoe companion to the Earth, the tenth known Earth horseshoe librator.[4] A close encounter with the Earth on 2015 December 14 caused the value of the semi-major axis of 2015 XX169 to drift slowly upwards, and the object evolved from an Aten asteroid to an Apollo asteroid about a year after this close approach.

    Discovery

    2015 XX169 was discovered on 2015 December 9 by R. G. Matheny observing with the 1.5-m reflector telescope at the Mount Lemmon Survey.[5] As of 6 December 2016, it has been observed 47 times with an observation arc of 363 days.[2]

    Orbit and orbital evolution

    2015 XX169 is currently an Apollo asteroid (Earth-crossing but with a period greater than a year). Its semi-major axis (currently 1.00096 AU) is similar to that of Earth (1.00074 AU), but it has a relatively low eccentricity (0.18431) and moderate orbital inclination (7.640°). It alternates between being an Apollo asteroid and being an Aten asteroid, changing dynamical status every 130 years approximately. As of 9 March 2016, this object is the 15th known Earth co-orbital and the 10th known object following a horseshoe path with respect to our planet. Asteroid 2015 XX169 follows an asymmetrical horseshoe path with respect to our planet; the value of its relative mean longitude oscillates about 180°, but enclosing 0°.[4]

    Physical properties

    With an absolute magnitude of 27.4 mag, it has a diameter in the range 9–22 meters (for an assumed albedo range of 0.20–0.04, respectively).

    See also

    Notes

    • ^ This is assuming an albedo of 0.20–0.04.

    References

    1. ↑ List Of Apollo Minor Planets
    2. 1 2 3 4 2015 XX169 at the JPL Small-Body Database
    3. ↑ Absolute-magnitude conversion table (H)
    4. 1 2 de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (1 April 2016). "A trio of horseshoes: past, present and future dynamical evolution of Earth co-orbital asteroids 2015 XX169, 2015 YA and 2015 YQ1". Astrophysics and Space Science. 361 (4): 121 (13 pages). arXiv:1603.02415. Bibcode:2016Ap&SS.361..121D. doi:10.1007/s10509-016-2711-6.
    5. ↑ Discovery MPEC
    Further reading

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