Cygnus X-1's interaction with its companion star results in what mass-exchange process?

Cygnus X-1's interaction with its companion star results in what mass-exchange process?

• A. Stripping material off the star
• B. Accretion by the black hole from the companion
• C. Tidal disruption of the star
• D. No mass exchange

Answer: (A)

Mass transfer in this binary happens when the black hole’s gravity pulls away the outer layers of its massive companion. The donor star loses material, which is then captured by the black hole and can form an accretion disk, producing the X-ray emission we observe. So the exchange is the stripping of material off the star, with that material ultimately accreting onto the black hole. The other ideas don’t fit because there isn’t a one-time tidal disruption or a scenario with no mass exchange; the ongoing transfer from the companion is what powers the system.

Mass transfer in this binary happens when the black hole’s gravity pulls away the outer layers of its massive companion. The donor star loses material, which is then captured by the black hole and can form an accretion disk, producing the X-ray emission we observe. So the exchange is the stripping of material off the star, with that material ultimately accreting onto the black hole. The other ideas don’t fit because there isn’t a one-time tidal disruption or a scenario with no mass exchange; the ongoing transfer from the companion is what powers the system.