  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.
