ASCA Science Highlights: X-ray Binaries
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X-ray Binaries (XRBs) are close binary systems in which a neutron star or a black hole is accreting material from a more or less normal star. These are among the brightest X-ray sources in the sky.- Strong and variable iron emission lines are seen in the massive XRB, Cen X-3, through its eclipse by the companion star.
- The excellent resolution of ASCA has resulted in the discovery of a strong neon line in the unusual low-mass XRB 4U1626-67, and other low energy features in several other systems.
- Some transient XRBs have recently been seen to eject jets of materials at close to the speed of light, much like in quasars: they are therefore dubbed "microquasars." Absorption features have been detected in the ASCA spectra of microquasars, giving scientists a unique method to study the jets.
- Transient XRBs in quiescence may have low enough accretion rates that material cannot radiate efficiently. They may therefore carry the heat inward without producing X-rays: this is called an Advection Dominated Accretion Flow, or ADAF. If the accreting object is a neutron star, then the ADAF will eventually hit its surface and must radiate X-rays; if there is a black hole, however, we may not see much radiation. This may be the case with the black hole transient V404 Cyg in quiescence.
This page created by Dr. Koji Mukai (USRA) at the U.S. ASCA Guest Observer Facility.
This file was last modified on Monday, 28-May-2001 18:26:04 EDT
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HEASARC Guest Observer Facility
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