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Cometary constraints on the planet forming environment
1Department of Physics and Astronomy, Arizona State University, Tempe 85287-1504, USA.
Advances in Space Research : the Official Journal of the Committee on Space Research (COSPAR)
|January 1, 1992
Summary
Comet Halley
Area of Science:
- Cosmochemistry
- Planetary Science
- Astrophysics
Background:
- Cometary abundances offer insights into the early solar nebula.
- Nitrogen-bearing species in comets are key to understanding solar system formation.
Purpose of the Study:
- To constrain models of the comet-forming environment using new cometary abundance data.
- To investigate the origin and processing of presolar materials in comets.
Main Methods:
- Analysis of N2, NH, and NH2 abundances in comets.
- Utilizing in situ data from the Giotto spacecraft (mass spectrometer and dust analyzer).
- Measuring carbon isotope ratios (12C/13C) in comet Halley's gas and dust.
Main Results:
- Elemental nitrogen in comet Halley's gas is depleted (~75x) relative to the Sun.
- Total nitrogen in gas and dust is ~1/6th of the solar value.
- Comet Halley shows a lower 12C/13C ratio (65±9) than the solar system (89±2).
Conclusions:
- Comet nuclei contain a significant fraction (~5%) of preserved circumstellar matter.
- Interstellar grain processing is less extensive than previously modeled.
- Comet nuclei likely formed in less harsh environments than primitive meteorites.