Artist's impression of 4U 1820-30
An artist's depiction of the low mass X-ray binary 4U 1820-30 in the core of the globular cluster NGC6624. This sytem contains a neutron star and a white dwarf. Its orbital period of 11 minutes is the shortest known of any LMXB, and in addition the system shows quasi-periodic oscillations (QPO) and burst behavior. The neutron star is surrounded by an accretion disk of material lost by the white dwarf.
In this image, gas is shown being stripped off the white dwarf star through Roche lobe overflow. The gas streams down and impacts the accretion disk, creating some azimuthal structure to the disk. It then spirals inward, heating due to frictional forces, emitting X-rays.
The scale of this system is shown, with Earth placed above the white dwarf and the limb of the sun shown at the bottom of the image.
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