4440 Tchantchès

Lore & Background

Tchantchès is a member of the Hungaria family, the innermost dense concentration of asteroids in the Solar System. It orbits the Sun at a distance of 1.8–2.1 AU once every 973 days, with an eccentricity of 0.08 and an inclination of 21° relative to the ecliptic. The body's observation arc begins with its official discovery observation, as no precoveries or prior identifications were made. Physically, Tchantchès has been characterized as a bright E-type asteroid by the NEOWISE mission. Between 2002 and 2014, numerous rotational lightcurves obtained by American astronomer Brian Warner at his Palmer Divide Observatory in Colorado gave a well-defined rotation period of 2.7883 hours with a brightness amplitude between 0.21 and 0.34 magnitude. Assuming an equatorial view on a simple triaxial ellipsoid, Warner estimates the body's shape to be elongated by 30% (a/b ratio of 1.3:1). Other lightcurves with a concurring period were obtained by French amateur astronomer Bernard Christophe in October 2002, and at the Palomar Transient Factory in California in July 2010. According to the survey carried out by NASA's NEOWISE mission, Tchantchès measures 2.093 kilometers in diameter and its surface has an outstandingly high albedo of 1.000, while the Collaborative Asteroid Lightcurve Link assumes an albedo of 0.30 – a compromise value between 0.4 and 0.2, corresponding to the Hungaria asteroids both as family and orbital group – and calculates a diameter of 4.42 kilometers with an absolute magnitude of 13.7. In 2013, reviewing the photometric data obtained in October 2005, Brian Warner found evidence that Tchantchès is possibly an asynchronous binary asteroid. Attenuations seen in the revised lightcurve indicated mutual occultations and eclipses events caused by a minor-planet moon orbiting Tchantchès. The satellite has an orbital period of 15.35 hours (2014 publication), and diameter of at least 25% of that of its primary. The Johnston's archive derives a satellite diameter of 510 meters and estimates a semi-major axis of 3.8 kilometers for its orbit. This minor planet was named after the popular folklore character Tchantchès (Walloon for François) in the French-speaking part of Belgium, where the discoverer François Dossin lives.

Reader's Guide

4440 Tchantchès is notable as a possible binary system within the Hungaria family, a group that forms the innermost dense concentration of asteroids in the Solar System. Its discovery on 23 December 1984 by François Dossin at Haute-Provence Observatory adds to the catalog of minor planets named after cultural figures, in this case the Belgian folklore character Tchantchès. The asteroid's physical characteristics, including a well-defined rotation period of 2.7883 hours and an elongated shape, have been determined through photometric observations by Brian Warner and others. The NEOWISE survey measured a diameter of 2.093 kilometers and an outstandingly high albedo of 1.000, while the Collaborative Asteroid Lightcurve Link assumes a different albedo of 0.30, leading to a calculated diameter of 4.42 kilometers. The most intriguing aspect is the evidence for a sub-kilometer satellite, making Tchantchès a candidate asynchronous binary asteroid. This finding, based on lightcurve attenuations from 2005 data, suggests mutual occultation and eclipse events, with the moon having an orbital period of 15.35 hours and an estimated diameter of 510 meters. The uncertainty in diameter and albedo, as well as the binary nature being described as 'possible,' underscores the ongoing research into this object.

Did You Know?

• It is named after the Belgian folklore character Tchantchès, a stubborn boy from Charlemagne's time depicted as a marionette.
• The asteroid is possibly a binary system, with a moon estimated to be 510 meters in diameter orbiting every 15.35 hours.
• NEOWISE measured its albedo as 1.000, an outstandingly high value, while other estimates assume an albedo of 0.30.