5899 Jedicke

Lore & Background

5899 Jedicke is a bright E-type asteroid and member of the Hungaria family, which forms the innermost dense concentration of asteroids in the Solar System. It orbits the Sun in the inner main-belt at a distance of 1.7–2.2 AU once every 2 years and 8 months (978 days), with an eccentricity of 0.12 and an inclination of 24° with respect to the ecliptic. It was first identified as 1978 EW3 at Crimea–Nauchnij in 1978, extending the body's observation arc by 10 years prior to its official discovery.

According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, the primary measures 2.672 kilometers in diameter with a very high albedo of 0.621. The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.30 and calculates a diameter of 3.51 kilometers. Between February 2010 and April 2016, astronomer Brian Warner obtained several rotational lightcurves; the best rated analysis from March 2013 gave a refined rotation period of 2.7481 hours with a brightness amplitude of 0.11 magnitude, superseding a preliminary estimate of 3–4 hours. However, an alternative period of 3.076 hours was found again in 2015, without any plausible explanation for a sudden 0.03 hour slowing that apparently took place between 2011 and 2012.

During Brian Warner's initial photometric observation in February 2010, it was revealed that Jedicke is a synchronous binary system with a minor-planet moon orbiting it every 16.7 hours. Based on observed mutual eclipse/occultation events, the satellite diameter measures at least 32% of that of Jedicke, translating into a diameter of 0.8–1.1 kilometers depending on the underlying size estimate of its primary. The 'Johnstonsarchive' estimates that the moon has a semi-major axis of 4.4 kilometers.

Reader's Guide

5899 Jedicke is significant as a binary Hungaria asteroid, a class that represents the innermost dense concentration of asteroids in the Solar System. Its discovery as a synchronous binary system during photometric observations in 2010 added to the growing catalog of asteroids with satellites, providing insights into the formation and dynamics of such pairs. The asteroid's naming after the Canadian Jedicke family—Peter, Robert, and June Zehr—honors their contributions to astronomy, including Peter's role as a prominent amateur astronomer and educator, Robert's discovery of two Jupiter-family comets, and June's shared observing sessions. The naming citation was prepared by Canadian astronomer David H. Levy and published by the Minor Planet Center on 12 July 1995. The asteroid's physical characteristics, including its high albedo and debated rotation period, highlight the challenges in asteroid science, such as reconciling different measurement methods (NEOWISE vs. lightcurve-based estimates) and unexplained rotational changes. Its binary nature and family membership make it a valuable object for studying asteroid evolution and the Hungaria group's properties.

Did You Know?

• 5899 Jedicke is a binary asteroid with a moon that orbits every 16.7 hours.
• It was discovered by American astronomer Carolyn Shoemaker at Palomar Observatory on 9 January 1986.
• The asteroid is named after the Canadian Jedicke family, including Peter, Robert, and June Zehr.
• Its rotation period may have slowed by 0.03 hours between 2011 and 2012, with no plausible explanation.