Dust from short-period comet P/Schwassmann–Wachmann 1 and replenishment of the interplanetary dust cloud

Abstract

IF the current abundance of interplanetary dust is representative of its long-term value¹, there must be a source of dust replenishing the ∼10⁷ g s^–1 (mostly in the form of particles of 10^–4 to 1 g) destroyed by dissipative processes². Short-period comets are the most likely such source³, but their dust production rate is uncertain. Coma spectrophotometry of several short-period comets excludes significant contributions of dust from them^4,5, but observations by the Infrared Astronomical Satellite⁶ have suggested the opposite. Here I use a numerical model⁷ to analyse an optical image of the dust tail of comet P/Schwassman–Wachmann 1, which contains information about grains 5 μm to 2 cm in diameter, ejected from 900 to 30 days before perihelion. During the three years covered by the model, the mass loss rate reached an estimated (6±3) × 10⁵ g s^–1, for an assumed albedo⁹ of 0.1 at the observation phase angle of 4°. This one short-period comet thus apparently provides ∼6% of the mass required to balance the losses of the interplanetary dust cloud.