Vulcanoids: An Examination of the Intra-Mercurial Region

Date
2019-09
Authors
Peltier, Lowell Francis
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Faculty of Graduate Studies and Research, University of Regina
Abstract

A review and discussion of the historical and modern ideas pertaining to the vulcanoid region of our solar system, and the theoretical asteroid population therein is presented here. Current observations constrain the maximum possible vulcanoid object size to somewhere between 5 and 10 km in diameter. Any object larger than this located within the putative vulcanoid zone, the region 0.06 AU to 0.25 AU away from the sun, should have been observed in past observations. With this in mind any modern day vulcanoid population would be small in number and size, but as yet, there is no compelling reason to rule out a population in general. This work explores the physical processes at work in the vulcanoid zone, primarily thermal (sublimation mass loss) and radiative (Poynting-Robertson drag, The Yarkovsky effect) effects are considered in this analysis. A key insight is the role that the variation in the luminosity of the sun over its lifespan has on the thermal and radiative effects inherent in the vulcanoid zone. In addition, the protective effects of a regolith composition are examined. Additionally, collisional effects, unipolar heating, and radiative rotational effects (YORP effect) are briefly explored. All of these effects will alter the lifespan of an asteroid in the region against destruction. Potential lifespans under various assumed initial conditions are explored and compared. Results show that the existence of vulcanoids in the modern day, and even at the end of the sun’s lifespan, is quite possible. Observational evidence presents a bleaker view of the putative vulcanoid population, but does not rule out the possibility entirely.

Description
A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Master of Science in Physics, University of Regina. vi, 95 p.
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