Determining the ages of comets from the fraction of crystalline dust

  title={Determining the ages of comets from the fraction of crystalline dust},
  author={Joseph A. Iii Nuth and Hugh G. M. Hill and Gunther Kletetschka},
The timescale for the accretion of bodies in the disk surrounding a young star depends upon a number of assumptions, but there are few observational constraints. In our own Solar System, measurements of meteoritic components can provide information about the inner regions of the nebula, but not the outer parts. Observations of the evolution of more massive protostellar systems (Herbig Ae/Be stars) imply that significant changes occur in the physical properties of their dust with time. The… 

Constraints on nebular dynamics and chemistry based on observations of annealed magnesium silicate grains in comets and in disks surrounding Herbig Ae/Be stars

It is suggested that a dynamic, large-scale circulation pattern brings processed dust and gas from the inner nebula back out into the region of cometesimal formation and that the composition of comets is determined by a chemical reaction network closely coupled to the dynamic transport of Dust and gas in the system.

Crystalline Silicates and Dust Processing in the Protoplanetary Disks of the Taurus Young Cluster

We characterize the crystalline-silicate content and spatial distribution of small dust grains in a large sample of protoplanetary disks in the Taurus-Auriga young cluster, using the Spitzer Space


The origin of crystalline grains in comets and the outer regions of protoplanetary disks remains a mystery. It has been suggested that such grains form via annealing of amorphous precursors in the

The radial distribution of dust species in young brown dwarf discs

We present a study of the radial distribution of dust species in young brown dwarf discs. Our work is based on a compositional analysis of the 10 and 20 µm silicate emission features for brown dwarfs

Condensation processes in astrophysical environments: The composition and structure of cometary grains

Abstract— We review the results of our recent experimental studies of astrophysical dust analogs. We discuss the condensation of amorphous silicates from mixed metal vapors, including evidence that

The Mineralogy of Interstellar and Circumstellar Dust in Galaxies

Dust in space is ubiquitous and is part of the cycle of matter in galaxies. The observed properties of dust change as a function of the astrophysical environment in which it is found. Dust can

The Earliest Chemical Dust Evolution in the Solar Nebula

Abstract The astrophysical aspects of the evolutionary path from dust to planets have been known for a long time but it was only recently that it could be followed by astronomical observations

Complex Protostellar Chemistry

Ciesla and Sandford demonstrate that even the outermost regions of the solar nebula can be a chemically active environment, and this finding could have consequences for the rest of the nebula.

Crystalline comet dust: Laboratory experiments on a simple silicate system

Abstract— Spectra for certain comets show the presence of crystalline silicate dust grains believed to have been incorporated during comet formation. While grain crystallization is widely assumed to



The Origin of Comets in the Solar Nebula: A Unified Model

Abstract Comets originated as icy planetesimals in the outer Solar System, as shown by dynamical studies and direct observation of objects in the Kuiper disk. Their nuclei have low strength

A Circumstellar Disk Around β Pictoris

A circumstellar disk has been observed optically around the fourth-magnitude star β Pictoris. First detected in the infrared by the Infrared Astronomy Satellite last year, the disk is seen to extend

Chemical heterogeneity and imperfect mixing in the solar nebula

It is shown that for the "standard" accretion disk model of the solar nebula, the efficiency of mixing the products of thermochemical processing from small to large disk radii depends only on the

The Silicates in the Disk of beta Pictoris

We have obtained intermediate-resolution (R≃50) infrared (2.6-13.5 μm) spectra of the particles in the circumstellar disk of β Pic. The silicate dust feature near 10 μm is broader and contains more

Protostars and Planets VI

Various papers on the formation of stars and planets are presented. The general topics addressed include: molecular clouds and star formation, young stellar objects and circumstellar disks, chemistry

Comet Halley: Spatial and Temporal Variability of the Silicate Emission Feature

Narrow- and broadband photometry of Comet Halley covering the wavelength range 2-20 microns was obtained at the NASA Infrared Telescope Facility (IRTF) both preperihelion (UT 1986 January 17 and 18)

The 8-13 micron spectra of comets and the composition of silicate grains

We have analyzed the existing spectra of seven comets which show an emission feature at 7.8-13 micrometers. Most have been converted to a common calibration, taking into account the SiO feature in

The identification of crystalline olivine in cometary silicates

An intermediate-resolution spectrum of the 8-13 micron region in comet Halley is obtained which shows a prominent silicate emission feature with structure not observed before in other comets or in

The Silicate Material in Comets

Silicates in comets appear to be a mix of high-temperature crystalline enstatite and forsterite plus glassy or amorphous grains that formed at lower temperatures. The mineral identifications from the

On neglect of nonlinear momentum terms in solar nebula accretion disk models

The standard model for accretion disks (e.g., Pringle, 1981; Lin and Papaloizou, 1985) parameterizes the radial eddy angular momentum flux which is quadratically nonlinear in velocity, solely by a