1.. HM Cancri is the binary with the shortest known period, of 5.4 minutes. What do you conclude?
a. One component must be a white dwarf or neutron star.
b. Both components must be a white dwarf or neutron star.
c. The system must have undergone a common-envelope phase.
d. [A and C]
e. [B and C]
2. We know many binaries with (nearly) stable mass transfer, but none in which it is highly unstable. Why?
a. Mass transfer is always stable.
b. Binaries that undergo a phase of highly unstable mass transfer are too rare.
c. Highly unstable mass transfer lasts only a short period of time.
d. [B and C]
3. Comparing two 1.4 solar mass neutron stars, one accreting from a 1 solar mass companion and the other from a 10 solar mass companion, you expect
a. stable accretion in both cases.
b. stable accretion for the 1 solar mass case and unstable for the 10 solar mass case.
c. unstable accretion for the 1 solar mass case and stable for the 10 solar mass case.
d. unstable accretion in both cases.
e. [there is not enough information to tell.]
a. One component must be a white dwarf or neutron star.
b. Both components must be a white dwarf or neutron star.
c. The system must have undergone a common-envelope phase.
d. [A and C]
e. [B and C]
2. We know many binaries with (nearly) stable mass transfer, but none in which it is highly unstable. Why?
a. Mass transfer is always stable.
b. Binaries that undergo a phase of highly unstable mass transfer are too rare.
c. Highly unstable mass transfer lasts only a short period of time.
d. [B and C]
3. Comparing two 1.4 solar mass neutron stars, one accreting from a 1 solar mass companion and the other from a 10 solar mass companion, you expect
a. stable accretion in both cases.
b. stable accretion for the 1 solar mass case and unstable for the 10 solar mass case.
c. unstable accretion for the 1 solar mass case and stable for the 10 solar mass case.
d. unstable accretion in both cases.
e. [there is not enough information to tell.]