We present high angular resolution PdBI images ( beam of \sim 0.33 ^ { \prime \prime } ) of the J =27 \rightarrow 26 line from several vibrational levels ( v _ { 7 } =1 and v _ { 6 } =1 ) of HC _ { 3 } N toward Cepheus A HW2 .
These images reveal the two main heating sources in the cluster : one centered in the disk collimating the HW2 radio jet ( the HW2 disk ) , and the other associated with a hot core 0.3 ^ { \prime \prime } northeast HW2 ( the HC ) .
This is the first time that vibrationally excited emission of HC _ { 3 } N is spatially resolved in a disk .
The kinematics of this emission shows that the HW2 disk rotates following a Keplerian law .
We derive the temperature profiles in the two objects from the excitation of HC _ { 3 } N along the HW2 disk and the HC .
These profiles reveal that both objects are centrally heated and show temperature gradients .
The inner and hotter regions have temperatures of 350 \pm 30 K and 270 \pm 20 K for the HW2 disk and the HC , respectively .
In the cooler and outer regions , the temperature drops to 250 \pm 30 K in the HW2 disk , and to 220 \pm 15 K in the HC .
The estimated luminosity of the heating source of the HW2 disk is \sim 2.2 \times 10 ^ { 4 } L _ { \odot } , and \sim 3000 L _ { \odot } for the HC .
The most massive protostar in the HW2 region is the powering source of the HW2 radio jet .
We discuss the formation of multiple systems in this cluster .
The proximity of the HC to HW2 suggest that these sources likely form a binary system of B stars , explaining the observed precession of the HW2 radio jet .