DH Wooden

Originally published in the journal Space Science Reviews, Volume 138, Nos 1-4. DOI 10.1007 s11214-008-9424-2 Springer Science+Business Media B.V. 2008 Abstract Comets are heterogeneous mixtures of interstellar and nebular materials. The degree of mixing of interstellar sources and nebular sources at different nuclear size scales holds the promise of revealing how cometary particles, cometesimals, and cometary nuclei accreted. We can ascribe cometary materials to interstellar and nebular...

Origins of Cometary Materials

Comet Size Distribution

Originally published in the journal Space Science Reviews, Volume 138, Nos 1-4. DOI 10.1007 s11214-007-9299-7 Springer Science+Business Media B.V. 2008 Abstract In this introductory presentation, material is categorized according to our state of knowledge What do we know, what do we think we know but don't know certainly, and what do we not know but often describe it as if it were a well-established fact about comets, their nuclei, their composition, and processes within comets and their...

Info

Fig. 1 The Tisserant constant versus the orbital energy (or reciprocal semimajor axis) of comets appearing in Marsden and William's (2005) catalogue. The dashed lines separate the three main dynamical classes of comets. LP comets with e > 0.98 were assumed to move on parabolic orbits (x 0). This is the reason why most LP comet appear aligned along the axis x 0. Sungrazers were removed from the sample where r is the Sun-comet radius vector expressed in the heliocentric frame of reference, and...

Discussion Interstellar Molecules in Comets

The cometary characteristics discussed here, when taken individually, present a puzzling picture and appear to indicate that comets contain materials from very different chemical Fig. 6 Equilibrium ortho para ratios in water, ammonia and formaldehyde as a function of temperature. The observed values are plotted for water and ammonia in ten comets. In two cases, the water OPR is gt 3, larger than the equilibrium ratio at any temperature. However, the error bars on these measurements are...

Introduction

Comet dust grain properties provide insights into physical conditions and processes in our protoplanetary disk, not only in the regions where nuclei accreted but also in the warmer regions of the disk inside the water snow line. The insights arise when we undertake four ventures 1 distinguish between 'interstellar' and 'nebular' sources for cometary refractory grains 2 identify the presence of cometary-like refractory grains in chondritic asteroidal materials 3 understand in detail how...