The location of Asteroidal Belt Comets (ABCs), in a comets' evolutionary diagram: The Lazarus Comets

Abstract

There is a group of newly recognized asteroids in the main belt that are exhibiting cometary characteristics. We will call them Asteroidal Belt Comets or ABCs. An analysis of their orbital and physical properties has resulted in the following conclusion: (1) We define the detached group, DG, as objects sublimating water that have aphelion distances Q < 4.5 AU. The detached group contains all the ABCs traditionally recognized, plus a few other members like 2P and 107P. With the above definition there are 11 members of the ABC group: 2P, 107P, 133P, 176P, 233P, 238P, C/2008 R1, C/2010 R2, 2011 CR42, 3200, and 300163 = 2006 VW139. (2) Active objects sublimate ices except collisioned asteroids, CA, P/2010 A2, 596 Scheila, and P/2012 F5 Gibbs, and 3200 Phaethon who was active due to sputtering. (3)We have calibrated the black body (color) temperature of comets vs perihelion distance, R. We find T = 325+-5 K/SQRT(R). (4) Using a mathematical model of the thermal wave we calculate the thickness of the dust layer on comet nuclei as 2.0+-0.5 m for comet 107P, 4.7+-1.2 m for comet 133P and 1.9+-0.5 m for a sample of 9 comets. (5) We have located three ABCs in an evolutionary diagram of Remaining Revolutions, RR, vs Water-Budget Age, WB-AGE. ABCs lie together in the upper right hand corner of the diagram. (6) RR vs WB-AGE defines the region of the graveyard of comets, objects with 1000 cy < WB-AGE (cy stands for comet years). Five members belong to the graveyard, 107P, 133P, 2006 VW139, D/1891 W1 Blanpain and 3200 Phaeton. Thus we propose that the asteroidal belt contains an enormous graveyard of ancient dormant and extinct rocky comets, that turn on (are rejuvenated), in response to a diminution of their perihelion distance.