Matter closest to the black hole in Cygnus X-1 orbits at approximately what fraction of the speed of light?

Unlock all questions

This demo includes only 20 questions. Upgrade to access hundreds of questions, flashcards, exam simulations, and disable ads.

Full question bankExam simulationsFlashcards
From $24.99Unlock all

Study for the NOVA Black Hole Apocalypse Astronomy Test. Explore astronomy with our rich content. Use flashcards and multiple-choice questions to enhance your knowledge. Prepare effectively and uncover the mysteries of black holes. Get ready for your exam!

Multiple Choice

Matter closest to the black hole in Cygnus X-1 orbits at approximately what fraction of the speed of light?

Explanation:
Matter in an accretion disk around a black hole can reach relativistic orbital speeds, especially right at the inner edge of the disk. For a non-spinning black hole, the innermost stable circular orbit sits at six gravitational radii, r = 6GM/c^2. Using the Newtonian estimate v ≈ sqrt(GM/r) gives v ≈ c / sqrt(6) ≈ 0.41c, a little over 40% of light speed. If the black hole spins, the inner edge can move closer and the orbital speed climbs, often reaching about half the speed of light for the inner disk regions in Cygnus X-1. So the closest matter is moving at roughly one-half of c. The other fractions would imply slower or much faster conditions than the typical inner-disk dynamics near such a system, with speeds approaching but not reaching the speed of light.

Matter in an accretion disk around a black hole can reach relativistic orbital speeds, especially right at the inner edge of the disk. For a non-spinning black hole, the innermost stable circular orbit sits at six gravitational radii, r = 6GM/c^2. Using the Newtonian estimate v ≈ sqrt(GM/r) gives v ≈ c / sqrt(6) ≈ 0.41c, a little over 40% of light speed. If the black hole spins, the inner edge can move closer and the orbital speed climbs, often reaching about half the speed of light for the inner disk regions in Cygnus X-1. So the closest matter is moving at roughly one-half of c. The other fractions would imply slower or much faster conditions than the typical inner-disk dynamics near such a system, with speeds approaching but not reaching the speed of light.

More Multiple Choice Questions
Subscribe

Get the latest from Examzify

You can unsubscribe at any time. Read our privacy policy