The Poynting-Robertson effect on meteor orbits (original) (raw)
NASA/ADS
Abstract
The Poynting-Robertson effect will operate to sweep small particles of the solar system into the sun at a cosmically rapid rate. Robertson derived an expression for the times of fall from initially circular orbits. Since, if other parameters are equal, the times are much less for orbits of high eccentricity, tables are given here to enable simple calculation of the times of fall in terms of the initial orbital elements, q and e, and particle radius and density. Total times of collapse are computed for several meteor showers. Since there is a linear dependence of the time on particle radius, the material in showers should ultimately be dispersed so that larger particles move with greater orbital a and e than do the smaller ones. This leads to the possibility of observing the Poynting-Robertson effect in a given swarm by a correlation of the observed mean magnitude of meteors with the time while the earth transits the shower. Such a correlation is not detected for any shower definitively; an upper limit, therefore, is set for the age of showers, ranging from five million years for some to less than one hundred thousand years for the Geminids. li some sporadic meteors had a common origin with the meteorites and asteroids, the operation of the Poynting-Robertson force requires that, for times of origin longer ago than the sixty million years suggested by Bauer, all material of radius less than 0.Q8 cm has been swept into the sun. Therefore, virtually no sporadic meteors fainter than the fifth magnitude can be arriving now on the earth unless they are cometary or interstellar in origin. For a time of three billion years the minimum radius is about 4 cm. The tables given for computation of the times of orbital contraction are valid for any radiating body of known mass and radiation by means of a simple correction. The process of contraction is faster by a factor of about 100,000 for B stars than for the sun. But, conversely, the Poynting-Robertson effect due to the general radiation of a galaxy is entirely too small to affect appreciably the dynamics of interstellar dust.
Publication:
The Astrophysical Journal
Pub Date:
January 1950
DOI:
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