AY 101-051                                                      Summer 2011 
                                      QUIZ #7

1.    Edwin Hubble showed that some ¿nebulae¿ are other galaxies, by finding
A)	VARIABLE STARS OF KNOWN LUMINOSITY.	c) redshifts in their spectra.
b)	known patterns of motion.		d) black holes in their cores.

2.	Which kind of galaxy normally hosts practically no star formation today?
A)	ELLIPTICAL.				c) barred spiral.
b)	ordinary spiral.			d) irregular.

3.	Over cosmic time, the number of quasars has
A)	RISEN RAPIDLY AND THEN FALLEN TO THE PRESENT DAY.
b)	increased continually.
c)	remained remarkable consistent.
d)	sometimes exceeded the number of galaxies.

4.	The spiral arms in some galaxies are most exactly traced by	
A)	REGIONS OF CURRENT STAR FORMATION.	c) stars moving together through space.
b)	the greatest number of stars.		d) material streaming from the center.

5.	Hubble¿s classification scheme for galaxies distinguishes
A)	ELLIPTICALS, BARRED AND ORDINARY SPIRALS, AND IRREGULARS.
b)	clockwise, counterclockwise, and edgewise spiral patterns.
c)	Seyfert galaxies, radio galaxies, and quasars.
d)	spherical, elliptical, and planar galaxies.

6.	The rapid changes in the brightness of quasars show that
a)	they must be very close to us.
B)	THEIR ENERGY SOURCE MUST BE VERY SMALL ON COSMIC SCALES.
c)	their inner regions must be rotating rapidly.
d)	their redshifts are continually changing.

7.	The central energy source in quasars is most likely to be
a)	a tight cluster of neutron stars.
b)	explosions of large numbers of supernovae.
c)	very massive first-generation stars.
D)	MATERIAL AROUND SUPERMASSIVE BLACK HOLES.

8. The properties of the stellar populations in the Milky Way suggest that 
e)	a) it has always had roughly its present size and shape.
F)	B) IT COLLAPSED FROM A LARGER AND ROUNDER FORM WHILE FORMING STARS.
g)	c) it has grown outward from the central bulge.
h)	d) the Sun is among its oldest stars.

9. Our Milky Way is which type of galaxy?
   	a) Elliptical.				c) Irregular.
   	B) SPIRAL.				d) Caramel-filled.

10.	 Stars of Population I differ from Population II in
a)	age.					c) orbital motion.
b)	chemical composition.			D) ALL OF THE ABOVE WAYS.