Blending the distinctions among groups of minor bodies: a portrait of the Centaur-comet “transition” object P/2010 C1 (Scotti)

Abstract

Aims. We present a portrait of the active Centaur P/2010 C1 (Scotti), observed with a well developed comet-like activity (central diffuse coma condensation and an extended sharp tail-like structure) at the heliocentric distance of rh = 5.5 AU. Methods. We analyse multicolour (B, V, R ,a ndI) images taken at the TNG telescope to characterise the dust coma of the active Centaur and to investigate its photometry, colours, and dust production, and to gain hints to its nucleus size. Results. P/2010 C1 (Scotti) has a small nucleus (<4.8 km in radius), with visual colour V − R = 0.49 ± 0.03 typical of the nuclei of Jupiter-family comets, but with a dust coma much redder (B − I = 2.37 ± 0.13) than both the Sun and the typical comet mucleus. It has an integrated R magnitude of mR = 21.41 ± 0.02 and R-Afρ = 34 ± 2 cm (all measured in the reference aperture of radius φ = 2.0 �� ), which is much lower than has been measured for other active Centaurs at similar heliocentric distances. Its dust production rate, Qd = 0.1–15 kg/s, depicts P/2010 C1 (Scotti) as a rather weak dust emitter, with a dust-loss rate comparable to that of the weakest Jupiter-family comets at shorter heliocentric distance and to the weakest active Centaur characterised to now.