Based on observations of supernova explosions in distant galaxies, it is predicted that 5 supernovae per century should occur in the Milky Way Galaxy, but roughly 1 supernova every 300 years has been observed from Earth. Which statement BEST explains this?

Where should an astronomer look for a supermassive black hole?

Astronomers believe that elements heavier than carbon can be created in each of these EXCEPT

The diameter of a typical neutron star of 2 solar masses is predicted to be approximately

As time progresses, the pulse rate for MOST solitary pulsars

The first direct gravitational waves to be directly observed were produced by

An eclipsing binary system consists of

For a massive star (e.g., 25 solar masses), core hydrogen fusion lasts for several million years. In contrast, the final stage of fusion, core silicon fusion lasts for only about

What major physical process is taking place inside stars that are on the main sequence in the Hertzsprung–Russell diagram?

Which of these fall within the typical range of dimensions of a giant molecular cloud in interstellar space?