| Annu. Rev. Astron. Astrophys. 1999. 37:
409-443 Copyright © 1999 by . All rights reserved |
3.3. Superluminal Motions in XTE J1748-288
Two major relativistic ejection sequences moving at least 20 mas
day-1 were observed in June 1998
(Hjellming et al
1998)
from thehard X-ray transient XTE J1748-288
(Smith et al 1998).
Each sequence appeared to begin with a one-sided relativistic ejection. The
ejecta are highly linearly polarized, and at a distance of 8 kpc, derived
from the HI 
21cm
absorption line, their motions would imply apparent speeds of 0.9c and
1.5c, and intrinsic velocities of more than 0.9c
(Hjellming et al 1998).
This is the first galactic source of relativistic jets where it has been
observed in real time that the jets collide with environmental material,
being decelerated while brightening at the leading edge of the jet.