143P/Kowal-Mrkos and the Shapes of Cometary Nuclei

Jewitt, David; Sheppard, Scott S.; Fernández, Yanga

doi:10.1086/374947

Cited by 41 publications

(43 citation statements)

References 49 publications

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“…It has not been detected in the pre-perihelion observation at r h = 5.4 AU (Weissman et al 2008), and presented stellar appearance at r h = 3.9 (Jewitt et al 2003) and 4.7 AU . Although probably poorly active at large heliocentric distances, the distant behaviour of this comet appears to be standard.…”

Section: Determination Of Activity Levelmentioning

confidence: 89%

A survey on the distant activity of short period comets

Epifani¹,

Palumbo²,

Colangeli³

2009

A&A

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Aims. The aim of this paper is to build up an inventory of observations of short period comets (SPCs) far from the Sun, and perform an analysis of general properties of the family, investigating the link between distant activity and present and historical orbital parameters. Methods. We gathered all the data available in the literature (as per June 2009) on SPCs ground-based and space observations at heliocentric distance r h > 3 AU. We analyzed the occurrence of distant activity with respect to: position on orbital branch, present orbital parameters (in particular the perihelion distance q), and their recent variations.Results. There is no sharp cut-off at any heliocentric distance, beyond which the cometary activity fades and only bare nuclei are observed. SPCs are more likely to be active post-perihelion than pre-perihelion: among a dataset of 90 comets (for which a heliocentric distance of analysis has been unequivocally established), 59% of the comets observed post-perihelion were detected as active targets, while only 22% of the comets observed pre-perihelion were active. There is a weak trend of comets with increasing perihelion distance to be more likely active at large heliocentric distance: among comets with q < 1.5 AU, only 5 out of 18 comets (28%) have been reported as active at large heliocentric distance, while among those with q > 3 AU, 14 out of 16 comets (88%) have been classified as active. A much less clear trend has been observed for distant cometary activity with semi-major axis a. No apparent appreciable link of a recent (or secular) increase of the perihelion temperature ΔT (due to a rapid decrease in the perihelion distance) with the present degree of distant activity has been observed.

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Section: Determination Of Activity Levelmentioning

confidence: 89%

A survey on the distant activity of short period comets

Epifani¹,

Palumbo²,

Colangeli³

2009

A&A

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“…Their surfaces are depleted in the ''ultrared'' matter that is a prominent feature of many of the Kuiper belt objects and Centaurs (Jewitt 2002). Their nuclei are too elongated to have been shaped only by collisional fragmentation of Kuiper belt parents (Jewitt et al 2003), while the timescales for outgassing torques to excite the nucleus spin are so short that the current rotations of these bodies are not likely to be primordial.…”

Section: Discussionmentioning

confidence: 99%

“…Period versus photometric range data in the figure are taken from Table 4 of Jewitt et al (2003). The plotted nuclei have all been measured photometrically, by the same technique as used in the present paper.…”

Section: Discussionmentioning

confidence: 99%

“…They have been stored at low temperatures (T 50 K) since their accretion in the protoplanetary disk of the Sun, 4.5 Gyr ago, and may preserve volatiles and other materials from that epoch. On the other hand, recent observations have uncovered differences in the surface colors (Jewitt 2002) and shapes (Jewitt, Sheppard, & Fernández 2003) of the cometary nuclei that are most likely evolutionary in nature, while it has long been recognized that the spins of the cometary nuclei are influenced by outgassing torques. The present state of knowledge is such that we do not yet understand either the initial conditions of the cometary nuclei or the processes of modification that have occurred following their injection into the inner solar system.…”

Section: Introductionmentioning

confidence: 99%

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The Nucleus of Comet 48P/Johnson

Jewitt

Sheppard

2004

Astron J

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We present new observations of short-period (Jupiter family) comet 48P/Johnson taken over several months when near $4 AU heliocentric distance. CCD photometry shows that this object has a pointlike inner surface brightness profile. It varies cyclically in brightness, with a light-curve period 14.50 AE 0.02 hr and photometric range Ám R = 0.32 AE 0.05 mag. We attribute these variations to the rotation of a bare, aspherical nucleus with projected semiaxes 3.0 Â 2.2 km (0.04 albedo assumed) and (two-peaked) rotation period 29.00 AE 0.04 hr. The phase coefficient of the nucleus is 0.059 AE 0.002 mag deg À1 , consistent with a low-albedo surface. A faint tail is evident in a deep composite image but appears to contribute little to the nucleus signal.

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“…Recent data suggest, in particular, that a large part of the fairly well studied nuclei have an elongated shape (for instance, P/Halley, P/Borelli, P/Tempel 1, etc) (Jewitt et al 2003), a feature characteristic of fragments originating from explosions of much larger bodies with geologically evolved structures (when their fragments of irregular shape are accelerated by a drag of the expanding gaseous products of the explosion more effectively and so escape the parent body easier), rather than of the products of accretion or, conversely, of collisions or collisional erosion. As for the quasi-spherical nucleus of P/Wild 2, the interesting features of its topography, including the irregular shape of the depression with abrupt walls, can be better understood if one takes into account the possibility of local burnout of isolated inclusions and layers enriched in combustible components.…”

Section: On the Origin Of Cometsmentioning

confidence: 99%

Deep Impactmission to Tempel 1 favours New Explosive Cosmogony of comets

Drobyshevski

Kumzerova

Schmidt

2007

Astronomical & Astrophysical Transactions

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The assumption that short-period (SP) comets are fragments of massive icy envelopes of Ganymede-like bodies saturated by products of ice electrolysis that underwent global explosions provides a plausible explanation of all known manifestations of comets, including the jet character of outflows, the presence of ions in the vicinity of the nucleus, the bursts and splitting of cometary nuclei, etc., with solar radiation initiating burning of the products of electrolysis in the nucleus. As shown persuasively by numerical simulation carried out in hydrodynamic approximation, the shock wave initiated by the Deep Impact (DI) impactor in the cometary ice saturated originally by the electrolysis products 2H 2 + O 2 is capable of activating under certain conditions exothermal reactions (of the type O 2 + H 2 + organics → H 2 O + CO + HCN + other products of incomplete burning of organics including its light and heavy pyrolyzed compounds, soot, etc.), which will slow down shock wave damping (forced detonation) and increase many times the energy release. As a result, the measured energetics of ejections and outflows from the crater have to exceed the DI energetics. Analysis of different clusters of the DI experiment data confirms these conclusions and expectations and thus it favours the planetary origin of comets.

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143P/Kowal-Mrkos and the Shapes of Cometary Nuclei

Cited by 41 publications

References 49 publications

A survey on the distant activity of short period comets

A survey on the distant activity of short period comets

The Nucleus of Comet 48P/Johnson

Deep Impactmission to Tempel 1 favours New Explosive Cosmogony of comets

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