Have stellar and supernovae radiations altered the pristine nature of comets?
✍ Scribed by S. Yabushita
- Publisher
- Springer Netherlands
- Year
- 1990
- Tongue
- English
- Weight
- 433 KB
- Volume
- 49
- Category
- Article
- ISSN
- 1573-0794
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✦ Synopsis
Effect of stellar and supernova radiations on cometary nuclei in the Oort cloud is investigated. Radiation dose received by a comet is calculated and compared with the one which Halley's comet receives by one perihelion passage. Stellar radiation provides 10 to 50% of Halley unit over 4 billion years. Inclusion of sublimation of volatile molecules such as CO or N2 does not allow the temperature to rise to 30 K by irradiation of bright OB stars, contrary to the claim of Stern and Shull.
A chance encounter with a SIi provides radiation dose which is just sufficient to raise to 30K the surface layer which is 1 m thick on the assumption that the radiation is wholly communicated to the interior. Thus, the comets remain pristine under the effect of stellar and SN radiations.