X-ray properties of the Galactic jet sources

X-ray properties of the Galactic jet sources are studied using the ASCA dat a. Two different types are found in the jet sources. One type, represented by the superluminal jet sources GRO J1655-40 and GRS1915+105, includes a ra pidly rotating compact star (a black hole or a neutron star) receiving supe r-critical mass accretion. On the other hand, relatively dim sources, such as GX339-4, 1E1740.7-2942 and GRS 1758-258, may constitute of the other typ e, which can produce jets at luminosities much lower than the Eddington lim it.