Activity of comets at large heliocentric distances pre-perihelion

Palumbo

Capria

et al. 2009

A&A

Aims. We study the distant dust environment of two Long Period Comets: C/2003 O1 (LINEAR) (observed at r h = 7.39 AU) and C/2004 K1 (Catalina) (observed at r h = 3.43 AU). The case of C/2003 O1 is particularly interesting since the comet has a quite large perihelion heliocentric distance (r h = 6.85 AU). Methods. We analysed R-band images taken at the CAHA 2.2 m telescope to characterise the properties of the cometary dust coma. The images of both comets were also used as input into an inverse numerical model, to derive information about the dynamical parameters of coma dust grains until a time ∼500 days before the observation. and its CO content: for a Q CO similar in value to those observed for other distant cometary objects, a comet radius R n from 13 to 17 km can be inferred.

Section: Comet C/2003 O1 (Linear)mentioning

confidence: 64%

The distant activity of the Long Period Comets C/2003 O1 (LINEAR) and C/2004 K1 (Catalina)

Palumbo

Capria

et al. 2009

A&A

“…Comets that have never been close enough to the Sun to experience significant heating require a different mechanism. Up to now, only seven such comets have been observed preperihelion (Korsun & Chorny 2003;Tozzi et al 2003;Meech et al 2009;Korsun et al 2010), and five of them had then a large (r > 5 AU) q passage.…”

Section: Introductionmentioning

confidence: 97%

“…Moreover, recent models of the solar system (Levison et al 2010) suggest that many other comets in the Oort Cloud may have an extrasolar origin (captures from protoplanetary discs of other stars). All the above models have strong consequences on the abundances and composition of trapped gas and on cometary activity (Meech et al 2009). …”

Section: Introductionmentioning

confidence: 99%

Observational results for eight long-period comets observed far from the Sun

Perna

Fabrizio

et al. 2013

A&A

Context. With this work we start a systematic analysis of the distant activity of several long-period comets in order to investigate the evolution of activity throughout the solar system and explore differences between comets that pass their perihelion at far or very close distances from the Sun. Aims. We present observational data for eight long-period comets, observed for the first time beyond r = 5 AU. Three targets have been characterised on their inward orbital branch. The others have passed their perihelion at quite large heliocentric distances (r q from 4.5 to 7.5 AU). Methods. We analyse multicolour broadband images (V, R, and I filters) taken at the Telescopio Nazionale Galileo to characterise the dust coma of the comets and investigate their morphology, photometry, colours, and dust production.Results. The morphological analysis shows many differences among the sample, from the large twisted structure present in the coma of comet C/2005 L3 to the regular coma envelope of C/2010 R1. The colour of the dust coma of all the comets is redder than the Sun. The Afρ value (measured in a reference aperture of radius ρ = 10 4 km) ranges from 114 ± 2 (C/2005 S4) to 5091 ± 47 (C/2005 L3) cm, depicting a scenario of bodies from moderately to very active. This is confirmed by the first-order quantitative estimate of the dust mass-loss rate for the comets that was obtained from the photometric data: assuming a grain velocity of v = 20 m/s, the dust production rate is comparable with, or even significantly larger than, that measured for many short-period ("old") comets at much smaller heliocentric distances.

“…When considering a proxy for the dust production rate, the comet C/2007 D1 is found to have an A f ρ value of the same order or even larger than that measured at lower heliocentric distances for some of the more active LPCs: e.g., C/2003 O1 (LONEOS), from ∼600 to ∼1300 cm at 7.02 AU (Mazzotta Epifani et al 2009;Meech et al 2009), and C/2001 G1 (LONEOS), ∼1800 cm at 8.3 AU (Meech et al 2009). …”

Section: Discussionmentioning

confidence: 77%

“…Several theoretical models of nucleus thermal evolution and internal differentiation (e.g., Tancredi et al 1994;Coradini et al 1997;Prialnik et al 2004) show that even out to r = 5−6 AU there is sufficient gas flux from sublimating water ice to lift small grains off the surface. Beyond this region, the sublimation of hypervolatiles such as CO or CO 2 has been invoked as the main driver for cometary activity, but it is unlikely that these more volatile ices condense out of the protosolar nebula in a pure form (Meech et al 2009, and references therein). They will instead be trapped as gas in the cells of amorphous water ice (Laufer et al 1987;Capria et al 2000a,b), and post-perihelion activity beyond 5 AU could be caused by perihelion heat wave that Based on observations collected at the Italian Telescopio Nazionale Galileo (TNG), operated on the island of La Palma by the Centro Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.…”

Section: Introductionmentioning

confidence: 99%

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

Dall’Ora

Fabrizio

et al. 2010

A&A

Aims. We report on the unusual distant activity of the dynamically new comet C/2007 D1 (LINEAR), observed at r h = 9.7 AU postperihelion. 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 A f ρ 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 dM d dt = 5.3 × 10 2 kg s −1 is measured, which implies that C/2007 D1 (LINEAR) is a very active comet despite its quite large perihelion distance.