Lux3 Heat transfer

hi all,

There was an interesting discussion on heatsink. here's mine:

LEDs are only converting 20-25% of the input into useful light. The rest being emitted off as heat. We all know the incandescant bulbs behave quite the same way but it disipitates most heat via radiation (the energy going forward in the same direction as the light spread - whatever it shines on gets heated up).

I am wondering how LEDs transfer its' heat. is it a backward heat conduction via the emitters' underbelly that is attached to the star heatsink? or is it same as the incans?
TIA! /ubbthreads/images/graemlins/cool.gif

Obiously it's not heat radiation as there's no infrared in the radiated spectrum. The LW3C's star gets really hot when operated at rated power without a heat sink so that's where the excess energy goes. My 37 LED reading light (avatar!) gets warm to the touch when operated for longer periods and that string uses only one watt!