X-ray bursters occur in binary star systems. The two types of stars that must be present to make up such an object are
A) a contact binary system of two red giants.
B) a white dwarf and a neutron star.
C) a white dwarf and a main-sequence star.
D) two neutron stars in a mass transfer binary.
E) a main-sequence or giant star and a neutron star in a mass transfer binary.
Question 2
When an electron moves from a lower to a higher energy state, a photon is ________.
Fill in the blank(s) with correct word