Images
Telescopes in the Atacama desert, Chile
Wolfe Creek crater (Kandimalal), Australia
Starpaths
Stellar paths in each cluster converge due to effects of perspective. Stars in each cluster move through space with a common velocity, like a flock of birds. When receding, the angle subtended by the cluster decreases. By combining this change in relative size with distances obtained from trigonometric parallaxes, astrometric radial velocities are obtained without using any spectroscopy. (Madsen, Dravins & Lindegren, A&A 381, 446) Click here for a high-resolution image.
Accretion onto a black hole in a close binary system
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