Journal Article

The cometary activity of Centaur P/2004 A1 (LONEOS)*

E. Mazzotta Epifani, M. Dall’Ora, D. Perna, P. Palumbo and L. Colangeli

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 415, issue 4, pages 3097-3106
Published in print August 2011 | ISSN: 0035-8711
Published online August 2011 | e-ISSN: 1365-2966 | DOI:
The cometary activity of Centaur P/2004 A1 (LONEOS)*

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P/2004 A1 (LONEOS) is one of the few active objects in the dynamical class of Centaurs. It has been recently injected into an inner orbit with a perihelion distance q = 5.5 au. The aim of this paper is to characterize the dust coma of this peculiar object, 2.5 yr after its first ‘new’ perihelion passage inside the Solar system. Broad-band visible images taken at the TNG telescope in 2007 February were analysed in order to characterize the dust coma of the Centaur: it was still quite active at rh = 6.5 au post-perihelion, with a coma and a well-developed wide tail-like structure, with a measured R-Afρ= 162 ± 10 cm in an aperture radius ρ= 104 km. The (VR) colour and the reddening values depict a scenario of a slightly red dust coma. A dust mass-loss rate of = 133 kg s−1 is derived from a photometric model, consistent with a scenario of a quite constant emission rate along the Centaur orbit. An upper limit for the Centaur radius of 3.5 km is derived by some realistic hypotheses on CO molecular production rate and on the mean grain scatterer size in the coma. Dynamical lifetime estimates compared to modelled loss rate result in a radius lower limit of 0.5 km, indicating therefore that the Centaur size is likely of the same order of magnitude of the short-period comets.

Keywords: minor planets, asteroids: individual: P/2004 A1 (LONEOS)

Journal Article.  8432 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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