2015 YA

2015 YA was discovered on 16 December 2015 by G. J. Leonard and R. G. Matheny observing for the Catalina Sky Survey.[7] As of 9 March 2016, it has been observed 47 times with an observation arc of 5 days.[2]

Animation of 2015 YA's orbit relative to Sun and Earth
  2015 YA ·   Sun ·   Earth

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°.[6]

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).

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).

• Discovery MPEC
• 2015 YA data at MPC
• ADS MPEC record
• 2015 YA at NeoDyS-2, Near Earth Objects—Dynamic Site
  • Ephemerides · Observation prediction · Orbital info · MOID · Proper elements · Observational info · Close approaches · Physical info · Orbit animation
• 2015 YA at ESA–space situational awareness
  • Ephemerides · Observations · Orbit · Physical properties · Summary
• 2015 YA at the JPL Small-Body Database