2015 YA

2015 YA

Discovery
Discovered by	Catalina Sky Survey
Discovery date	December 16, 2015
Designations
Designation	2015 YA
Minor planet category	Aten asteroid, Earth crosser
Orbital characteristics
Epoch January 13, 2016 (JD 2457400.5)
Uncertainty parameter 6
Observation arc	5 days
Aphelion	1.27598 AU
Perihelion	0.71908 AU
Semi-major axis	0.99753 AU
Eccentricity	0.2791
Orbital period (sidereal)	0.99632 y (363.91 d)
Mean anomaly	99.79°
Inclination	1.6249°
Longitude of ascending node	255.3291°
Argument of perihelion	83.849°
Earth MOID	0.00356 AU
Physical characteristics
Dimensions	9–22 m[a]
Absolute magnitude (H)	27.4

2015 YA (also written 2015 YA) is an Aten asteroid that is a temporary horseshoe companion to the Earth, the eleventh known Earth horseshoe librator. Prior to a close encounter with the Earth on 2015 December 15 2015 YA was an Apollo asteroid.

Discovery

2015 YA was discovered on 2015 December 16 G. J. Leonard and R. G. Matheny observing for the Catalina Sky Survey. As of 9 March 2016, it has been observed 47 times with an observation arc of 5 days.

Orbit and orbital evolution

2015 YA is currently an Aten asteroid (Earth-crossing but with a period less than a year). Its semi-major axis (currently 0.99753 AU) is similar to that of Earth (1.00074 AU), but it has a moderate eccentricity (0.2791) and very low orbital inclination (1.6249°). It alternates between being an Aten asteroid and being an Apollo asteroid, although its orbital evolution is rather chaotic. As of 9 March 2016, this object is the 16th known Earth co-orbital and the 11th known object following a horseshoe path with respect to our planet. Asteroid 2015 YA follows an asymmetrical horseshoe path with respect to our planet; the value of its relative mean longitude oscillates about 180°, but enclosing 0°.

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 0.04–0.20, respectively).

See also

• 54509 YORP
• (419624) 2010 SO16
• 3753 Cruithne
• 2015 SO2
• 2015 XX169
• 2015 YQ1

Notes

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

References

Further reading

• Understanding the Distribution of Near-Earth Asteroids Bottke, W. F., Jedicke, R., Morbidelli, A., Petit, J.-M., Gladman, B. 2000, Science, Vol. 288, Issue 5474, pp. 2190–2194.
• A Numerical Survey of Transient Co-orbitals of the Terrestrial Planets Christou, A. A. 2000, Icarus, Vol. 144, Issue 1, pp. 1–20.
• Debiased Orbital and Absolute Magnitude Distribution of the Near-Earth Objects Bottke, W. F., Morbidelli, A., Jedicke, R., Petit, J.-M., Levison, H. F., Michel, P., Metcalfe, T. S. 2002, Icarus, Vol. 156, Issue 2, pp. 399–433.
• Transient co-orbital asteroids Brasser, R., Innanen, K. A., Connors, M., Veillet, C., Wiegert, P., Mikkola, S., Chodas, P. W. 2004, Icarus, Vol. 171, Issue 1, pp. 102–109.
• A trio of horseshoes: past, present and future dynamical evolution of Earth co-orbital asteroids 2015 XX₁₆₉, 2015 YA and 2015 YQ₁ de la Fuente Marcos, C., de la Fuente Marcos, R. 2016, Astrophysics and Space Science, Vol. 361, Issue 4, article 121 (13 pp).

External links

• Discovery MPEC
• 2015 YA data at MPC
• ADS MPEC record
• 2015 YA at the JPL Small-Body Database