379 Huenna

Lore & Background

Huenna was discovered on 8 January 1894 by French astronomer Auguste Charlois at Nice Observatory, announced in Astronomische Nachrichten on 17 January under the old-style provisional designation 1894 AQ. By 1902 it was named Huenna, the Latin form of Hven, an archaic spelling of the Swedish island Ven, where Tycho Brahe built observatories in the late 16th century. Its provisional designation was later retroactively changed to A894 AA under the modern system.

Huenna orbits the Sun at an average distance of 3.14 AU, with a perihelion of 2.58 AU and aphelion of 3.70 AU, taking 5.57 years to complete one orbit. It is a member of the Themis family, thought to have originated from the catastrophic disruption of a large object roughly 2.5±1.0 billion years ago. Its diameter is estimated at 87.5 ± 8.2 km, with a rotation period of 14.14 hours. It is classified as a primitive B-type under Tholen and a C-type under SMASSII, though a 2022 study supported B-type and conflicted with C-type, possibly due to sublimation of icy material creating a faint dusty coma.

Huenna has one known moon, S/2003 (379) 1, discovered on 14 August 2003 by Jean-Luc Margot at Keck Observatory. The moon orbits with a semi-major axis of 3,487.9 km, taking 80.216 days, with an eccentricity of 0.283 and an inclination of 151.19° relative to the ecliptic. Its estimated diameter is 3.72 ± 0.6 km, making it one of the smallest known satellites of a large asteroid. Its distant, eccentric orbit suggests it may be a captured object rather than formed from a giant collision.

Reader's Guide

379 Huenna is significant as a large main-belt asteroid with a small, distant moon that challenges typical formation models for asteroid satellites. While most small moons of large asteroids are thought to form from giant collisions and have circular, close-in orbits, S/2003 (379) 1 orbits Huenna on a wide, eccentric, and highly inclined path, suggesting a different origin—possibly capture from another Themis family member or an interloper. The asteroid itself is a primitive B-type or C-type, and a 2022 spectral study raised the possibility that sublimating ice from its surface creates a faint dusty coma, which would be unusual for a main-belt object. Its membership in the Themis family links it to a major collisional event about 2.5 billion years ago. The moon's discovery in 2003 using adaptive optics at Keck Observatory highlights the role of advanced ground-based telescopes in revealing binary systems among small bodies. Huenna's system mass and derived density provide constraints on its internal composition, and its rotation period of 14.14 hours has been measured from lightcurve observations.

Did You Know?

• Huenna was named after the Swedish island of Ven, where Tycho Brahe built two observatories in the late 16th century.
• Its moon, S/2003 (379) 1, orbits at a distance roughly half of Huenna's Hill radius, making it loosely bound.
• A 2022 study suggested that sublimation of icy material from Huenna's surface may create a faint dusty coma.
• The moon's orbit is inclined by 151.19° relative to the ecliptic, indicating a retrograde or highly tilted path.