Notes 4 Exam Flashcards
What perception of the Milky Way Galaxy did astronomers have at the beginning of last century?
They believed that the Milky Way was the entire universe.
Which is the correct description of the Sun’s location within the Milky Way?
right side of the galactic bulge
8 kpc from it.
Measuring which two quantities of our galaxy allow for a determination (calculation) of the Milky Way’s mass?
kiloparsec and parsec
What observation of the Galaxy suggests that it is much larger than the halo component, and that it contains a large amount of matter not in the form of stars?
The rotation curve
Matter belonging to the Galaxy can be traced out to _______ [what distance] from the center.
15kpc
The object located at the center of the Galaxy is calculated and predicted to be a ________.
Galactic bulge
All RR Lyrae stars have about the same ___ .
luminosity of about 100 suns
With respect to age, the stars in the Galactic disk are ____ .
young compared to stars in the galactic halo
The Sun’s motion in our galaxy is in a(n) ______ orbit.
ellipse
Our solar system lives in the Milky Way’s ____ .
The sun is about 26,000 light-years from the center of the Milky Way Galaxy
The nearest major galaxy to the Milky Way is the ____ galaxy.
Andromeda
To determine a Cepheid variable’s distance, one must measure its ___.
The apparent brightness. Also, the period of the star, which is related to its real brightness.
The rotation curve for our galaxy (speed vs distance from center) is _________, compared to the “Keplerian curve”, at large distance from the center.
higher
Most of the mass of the Milky Way is predicted to exist in the form of ___ .
dark matter
The interstellar ______ absorbs light from stars and makes them appear fainter than they otherwise would appear.
gas or dust
The fuzzy band across the sky which we call the Milky Way is actually the light from millions of stars in the ______ component of the Galaxy.
galactic disk
Neutral hydrogen gas, bright young O and B stars, Cepheid variable stars, and emission nebulae all map out the position of the ______, in the Milky Way.
spiral arms
The Sun is currently estimated to be about ______ from the center of the Galaxy.
The sun is 8 kiloparsecs from the center
The age of our galaxy is estimated by determining the ages of the oldest objects in the ______.
halo
Variable stars are stars whose ______ varies with time.
apparent brightness
Which of the following types of galaxies is not one of the Hubble types of galaxy?
Irregular Lrr galaxy, active
galaxy, dwarf galaxy.
Which type of galaxy has a stellar disk but without gas or dust?
spiral galaxy
Elliptical galaxies tend to contain _____ stars and lack _____.
x ray halo of hot gas, spiral structure
A spiral galaxy whose central region is a bright, bar-like source of light is called a(n) ______ galaxy.
barred spiral
When two galaxies move very closely to each other, their ______ may dramatically rearrange their visible structures.
stars
Giant elliptical galaxies may be the result of ______.
the collision of two galaxies
Going from galaxy type Sa, to Sb, to Sc, there is a decline in the size of the galaxy’s _______.
bulges
Irregular galaxies, in size, tend to be _______ than spiral galaxies.
smaller
When galaxies collide, the individual stars, generally, do not collide. (True/False)
true
The Hubble Ultra Deep field is data from galaxies that are _____ .
-
Galaxies evolve by ____ .
mergers and interactions.
In terms of luminosity, quasars are ____ .
bright
Star formation in the earliest galaxies of the universe was ____
-
Galaxies at high redshift (i.e. great distances, or equivalently, younger) are ___ compared to low redshift galaxies (nearby and older).
smaller
