The activity of comet C/2007 D1 (LINEAR) at 9.7 AU from the Sun^*

¹ INAF-Osservatorio Astronomico di Capodimonte, via Moiariello 16, 80131 Napoli, Italy e-mail: epifani@oacn.inaf.it
² Fundación Galileo Galilei - INAF, Rambla José Ana Fernández Pérez, 7, 38712 Breña Baja, TF, Spain
³ Instituto de Astrofísica de Canarias, c/vía Láctea s/n, 38200, La Laguna, Tenerife, Spain
⁴ Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain
⁵ Universitá Parthenope, Dip. Scienze Applicate, Centro Direzionale Isola C4, 80143 Napoli, Italy

Received: 23 October 2009
Accepted: 5 January 2010

Abstract

Aims. We report on the unusual distant activity of the dynamically new comet C/2007 D1 (LINEAR), observed at r_h = 9.7 AU post-perihelion. This comet is particularly interesting because of its quite large perihelion distance (r_q = 8.8 AU).

Methods. We analyse V and R band images taken at the TNG telescope to characterise the dust coma of the comet and investigate its photometry, colours, and dust production.

Results. The colour of the dust is redder than the Sun (V - R = 0.505 ± 0.093 at the photometric aperture of radius 2.2”). The Afρ value is measured to be 1983 ± 81 cm for an aperture of radius = 2.2”. An upper limit to the cometary nucleus radius of a_N ≤ 18 km is derived. A dust mass-loss rate of = 5.3 × 10² kg s^-1 is measured, which implies that C/2007 D1 (LINEAR) is a very active comet despite its quite large perihelion distance.