dietz%USC-CSE@USC-ECL.ARPA (06/09/84)
The latest issue of Science has a paper about the material in orbit around Vega. The author argues the total mass of the 85 K material is much less than 300 times the mass of the earth. The problem is this: although primordial particles less than a millimeter across would have decayed into Vega by now, small particles may continually be generated in the ring by collisions of larger bodies. These small particles will dominate IR emission due to their high surface area. The paper estimated the mass of the ring to be around 15 - 45 earths, with the matter there mainly cometary in nature. There may also be 12 micron IR evidence of material much closer to Vega, perhaps consisting of asteroidal debris. The fact that the emmission from comets cuts off closer than 85 AU from Vega argues the comets there have been destroyed, probably accreted onto or ejected by planets.