THE GALACTIC-CENTER

An attempt is made to present all the relevant observations of our galactic centre and to explain them by means of a working scheme that involves a minimum number of ad hoc assumptions. In this scheme, the central engine is Sgr A*, a supermassive star of some 103M⊙ and surface temperature ≲3.6×104 K in Keplerian rotation, fuelled by the strongly magnetized disk. It drives both a non-thermal (pair-plasma) wind and a thermal wind. Interactions with the central star cluster and with the circumnuclear disk give rise to the thermal vortex Sgr A West and to the non-thermal spill-over bubble Sgr A East. The relativistic pair plasma escapes supersonically through the galactic chimney into the galactic twin jets, as in Seyfert galaxies. © 1990 Kluwer Academic Publishers.