Unit 2 Chapter 31: Galaxies and the Universe

Question 1

What is the Milky Way

Answer 1

The Milky Way is our home Galaxy, it is a disk made up of billions of stars orbiting a central point.

Question 2

What are variable stars

Answer 2

stars that reside in the Giant branch of the H-R diagram. They pulsate brightness because of the expansion and contraction in their outer layers. These stars can be used to estimate distance to places in the Galaxy.
RR Lyrae Variables: pulsation period between 1.5h to 1 day, and on average, they have the same luminosity
Cephid Variables: pulsation periods between 1 to 100 days. The greater the pulsation period, the more luminous the star

Question 3

Describe the Milky Way

Answer 3

the galactic center, also called the nucleus, is surrounded by a nuclear bulge, which sticks out of the galactic disk, around the nuclear bulge is the halo, the spherical region where globular clusters are located. The milky way has 4 major spiral arms

Question 4

How was the Milky Way formed

Answer 4

the galaxy began as a spherical cloud in space,the first star formed while this cloud was still a sphere that explains why the halo is spherical. the cloud collapsed from its own gravity and formed a disk-like shape.

Question 5

describe how astronomers classify galaxies

Answer 5

DISK-LIKE GALAXIES WITH SPIRAL ARMS: 
-normal spirals-S
-barred spirals-SB
-a= tightly wound
-c=loosely wound 
-flat disks without spiral arms-SO
ELLIPTICAL GALAXIES-NO DISK AND SPIRAL ARMS: 
-divided into subclasses based on their apparent ratio of major and minor arms 
-E
-round=E0
-elongated=E7

no distinct shape= Err.

Question 6

describe expansion of the universe

Answer 6

all points are moving away from other points, the farther something is away, the faster it moves away.
V=Hd

Question 7

Superclusters

Answer 7

clusters of galaxies that contain many local groups

Question 8

cosmology

Answer 8

the study of the universe, its current nature and its past and origin

Question 9

quasars

Answer 9

star-like objects with emission lines in their spectra

Question 10

The Big Bang Theory

Answer 10

the steady expansion from a single point in space. The universe started as a singularity

Question 11

what are the oldest objects in the Milky Way

Answer 11

globular clusters

Question 12

where in the milky way are stars still being formed

Answer 12

in spiral arms

Question 13

Population I

Answer 13

New spiral arm stars-sun, heavy elements

Question 14

Population II

Answer 14

Halo and Bulge, trace heavy elements