____________ galaxies contain a supermassive black hole at their centers while active nuclei are present in ____________of galaxies
a. Most; a few percent
b. Most; the majority
c. A small minority; a few percent
d. A small minority; the majority
Question 2
Star clusters are important to our study of stars because
a. all stars formed in star clusters.
b. the Sun was once a member of a globular cluster.
c. they give us a method to test the our theories and models of stellar evolution.
d. they are the only objects that contain Cepheid variables.
e. All of the other choices are correct.
An illustration of the helium atom, depicting the nucleus (pink) and the electron cloud distribution
Accretion Disk Around a Supermassive Black Hole
Galaxies Forming by Combining Smaller Units
The Ku Klux Klan forces John Campbell, a black man, to beg for his life in Moore County, North Carol
Black and White Out-Migration from Virginia and North and South Carolina, 1870–1940 (in thousands)
HIV cycle in an infected cell: (a) latent infection; (b) active infection.