41 Daphne

Lore & Background

41 Daphne was discovered by H. Goldschmidt on 22 May 1856, and named after the Greek nymph Daphne, who was turned into a laurel tree. Incorrect orbital calculations initially led to 56 Melete being mistaken for a second sighting of Daphne; the asteroid was not sighted again until 31 August 1862. Its orbit places it in a 9:22 mean motion resonance with Mars, and its computed Lyapunov time of 14,000 years indicates a chaotic orbit that will change randomly over time due to gravitational perturbations of the planets.

The asteroid has a dark surface and is probably composed of primitive carbonaceous chondrites, with spectra displaying evidence of aqueous alteration. In 1999, Daphne occulted three stars, and on 2 July 1999, produced eleven chords indicating an ellipsoid of 213×160 km. Lightcurves suggest the asteroid is irregular in shape. Daphne was observed by Arecibo radar in April 2008, which gave a near surface solid density of 2.4+0.7−0.5 g cm−3.

41 Daphne has at least one satellite, named Peneius (provisionally S/2008 (41) 1), identified on 28 March 2008. It has a projected separation of 443 km, an orbital period of approximately 1.1 days, and an estimated diameter of less than 2 km. If these preliminary observations hold up, this binary system has the most extreme size ratio known. In Greek myth, Pēneios is the god of the river of that name, and father of Daphne.

Reader's Guide

41 Daphne holds significance as a large, primitive asteroid whose dark surface and carbonaceous chondrite composition offer clues to early solar system materials, with spectral evidence of aqueous alteration suggesting past water activity. Its chaotic orbit, with a Lyapunov time of 14,000 years and a 9:22 mean motion resonance with Mars, makes it a dynamic object of interest for studying gravitational perturbations. The asteroid's binary system, with a satellite less than 2 km in diameter orbiting at a separation of 443 km, is notable for potentially having the most extreme size ratio between a primary and its moon among known binaries. Radar observations from Arecibo in April 2008 provided a near surface solid density estimate, while occultation data in 1999 revealed an ellipsoidal shape of 213×160 km. The discovery history, including the initial confusion with 56 Melete and the long gap until its next sighting in 1862, adds to its legacy as a well-studied but elusive object in the asteroid belt.

Did You Know?

• It has a satellite named Peneius, provisionally designated S/2008 (41) 1, identified on 28 March 2008.
• The asteroid's orbit is in a 9:22 mean motion resonance with Mars and has a Lyapunov time of 14,000 years.