Photometry of the Oort Cloud comet C/2009 P1(Garradd): pre-perihelion observations at 5.7 and 2.5 AU

Mazzotta Epifani, E.; Snodgrass, C.; Perna, D.; Dall’Ora, M.; Palumbo, P.; Della Corte, V.; Alvarez-Candal, A.; Melita, M. and Rotundi, A (2016). Photometry of the Oort Cloud comet C/2009 P1(Garradd): pre-perihelion observations at 5.7 and 2.5 AU. Planetary And Space Science, 132 pp. 23–31.

DOI: https://doi.org/10.1016/j.pss.2016.07.007

Abstract

The aim of this paper is to contribute to the characterization of the general properties of the Long Period Comets (LPCs) family, and in particular to report on the dust environment of comet C/2009 P1 (Garradd).

The comet was observed at two epochs pre-perihelion, at ~6 AU and at ~2.5 AU: broad-band images have been used to investigate its coma morphology and properties and to model the dust production rate.

Comet C/2009 P1 (Garradd) is one of the most active and “dust producing” LPCs ever observed, even at the large heliocentric distance r_h~6 AU. Its coma presents a complex morphology, with subtle structures underlying the classical fan-shaped tail, and, at r_h~2.5 AU, also jet-like structures and spiralling outflows. In the reference aperture of radius ρ=5°×10⁴ km, the R-Afρ is 3693±156 cm and 6368±412 cm, in August 2010 (r_h~6 AU) and July 2011 (r_h~2.5 AU), respectively. The application of a first order photometric model, under realistic assumptions on grain geometric albedo, power-law dust size distribution, phase darkening function and grain dust outflow velocity, yielded a measure of the dust production rate for the two epochs of observation of Qd=7.27×10² kg/s and Qd=1.37×10³ kg/s, respectively, for a reference outflow dust velocity of v_small=25 m/s for small (0.1–10 µm) grains and v_large=1 m/s for large (10 µm–1 cm) grains.

These results suggest that comet Garradd is one of the most active minor bodies observed in recent years, highly contributing to the continuous replenishment of the Interplanetary Dust Complex also in the outer Solar System, and pose important constraints on the mechanism(s) driving the cometary activity at large heliocentric distances.

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About

• Item ORO ID
• 47269
• Item Type
• Journal Item
• ISSN
• 0032-0633
• Keywords
• comets; stellar dust; coma
• Academic Unit or School
• Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
  Faculty of Science, Technology, Engineering and Mathematics (STEM)
• Research Group
• Space
• Copyright Holders
• © 2016 Elsevier B.V.
• Depositing User
• Colin Snodgrass