4,884 research outputs found
Hubble Space Telescope Observations of the Black Hole X-ray Transient GRO J0422+32 Near Quiescence
We present HST/FOS ultraviolet and optical spectroscopy of the black hole
X-ray transient GRO J0422+32 shortly before the system reached quiescence. We
find that the accretion spectrum from 2500-9000A can be very well fit by a
self-absorbed synchrotron model, with superposed HI and MgII emission lines.
The explanations we suggest for this spectrum are that it is either due to
active coronal regions above a geometrically thin accretion disc, or that the
disc is evaporated into an advective flow.Comment: 7 pages with 7 postscript figures included, uses mn.sty. Accepted for
publication in MNRA
Doppler Tomography of XTE J2123-058 and Other Neutron Star LMXBs
We describe Doppler tomography obtained in the 1998 outburst of the neutron
star low mass X-ray binary (LMXB) XTE J2123-058. This analysis, and other
aspects of phase-resolved spectroscopy, indicate similarities to SW Sex
systems, except that anomalous emission kinematics are seen in HeII, whilst
phase 0.5 absorption is confined to H alpha. This separation of these effects
may provide tighter constraints on models in the LMXB case than is possible for
SW Sex systems. We will compare results for other LMXBs which appear to show
similar kinematics and discuss how models for the SW Sex phenomenon can be
adapted to these systems. Finally we will summarise the limited Doppler
tomography performed on the class of neutron star LMXBs as a whole, and discuss
whether any common patterns can yet be identified.Comment: 8 pages, 5 postscript figures. To appear in Proceedings of
Astro-Tomography Workshop, Brussels, July 2000, Eds. H. Boffin, D. Steeghs,
Springer-Verlag Lecture Notes in Physic
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