Astronomy Unit 7- Galaxies & Beyond

galaxy thickness

1,000 light years

galaxy diameter

100,000 light years

age of galaxy

15 billion years old

What type of galaxy do we live in?

Barred Spiral

What is the name of the galaxy that is closest in proximity to the Milky Way?

Canis Major

What makes up the greatest amount of mass in the universe?

Dark Matter

What is another name for the arms of a spiral galaxy?

Density waves

How does the shape of an elliptical galaxy change as it moves from E0 to E7?

E7 is more flattened/elliptic than E0, which is spherical.

Who developed our current system for naming/classifying galaxies?

Hubble

What does the M stand for in the name of a galaxy? (ex: M31) What about NGC?

M= Messier NGC = New General Catalogue

Name of our galaxy?

Milky Way

What are the major members of the Local Group?

Milky Way, Andromeda, M31, LMC, and SMC

what arm do we live in

Orion

How does the shape of a Barred Spiral galaxy change as it moves from SBa to SBc?

SBc has more defined arms than SBa

How does the shape of a spiral galaxy change as it moves from Sa to Sc?

Sc has more defines arms than Sa

What does Hubble's law state?

Something far away will travel faster and everything is moving away from everything else.

Why are stars of lower metal content thought to be older than stars of higher metal content?

They would have been formed directly after the Big Bang and Hydrogen and Helium would have been the only things available during the formation

What are the characteristics of an Elliptical galaxy?

Very little gas and dust, very little star formation, only old stars.

What are Population II stars? Are they old or young? Are they rich in metals or not? Where would you find them in our galaxy?

Very old main sequence stars, 4% metal, found in globular clusters in halo

What is the Zone of Avoidance? Why does it look this way? How did it help explain the shape of our galaxy?

band running around the sky in which few galaxies are visible. This tells us there is a bulge in center

What is believed to be at the center of most of the galaxies we have observed?

black hole, usually super massive

How were we able to determine that Sun is not at (or near) the center of our galaxy?

by plotting the globular clusters we saw a huge spherical system and we could determine where the center was. our sun is in one of the arms.

What are the three primary components of our galaxy?

disk, halo, bulge

What is the most common type of galaxy?

dwarf elliptical galaxies

Which galaxy is made up entirely of old stars?

elliptical galaxies

What is an active galaxy? Is our galaxy "active"?

emit energy because black hole at the center is accreting material. Milky Way isnt.

What did Shapley use to plot the center of the Milky Way?

globular clusters

How have we determined that dark matter exists?

gravitational lensing, speed of galaxy rotation, temperature distribution

Which galaxy has the most formation of new stars?

irregular galazies

Sketch the Milky Way as viewed from above the plane of the disk. Include and label the nucleus, spiral arms, the Sun's position, and the halo.

label

What is a lenticular galaxy? How can it be described? What type of galaxy is it associated with?

lens-shaped galaxy disk and central bulge and no spiral arms. it could be an older spiral galaxy whose spiral arms were pulled inward or it could be a spiral galaxy viewed from the side.

What are the characteristics of a Barred spiral galaxy?

lost of gas and dust, rotates fast, old and new stars, central bar-shapped stucture and composed of stars.

What are the characteristics of a spiral galaxy?

lots of gas and dust, lots of star formation, contains old and new stars.

What is the most important process producing the types of galaxies we see today?

merging of material

What are the characteristics of an Irregular galaxy?

mostly gas an dust, most star formation , old and new stars, no distinct shape

Why are spiral galaxies blue?

new stars forming in arms

What are Population III stars? Why are they theoretical?

theoretical stars, contain no metals, we have never seen one-came right after big bang and had very large masses and short lives.

where is the center of our galaxy

toward sagittarius

What are RR Lyrae and Cepheid variables used for?

used to determine distance

What are Population I stars? Are they old or young? Are they rich in metals or not? Where would you find them in our galaxy?

younger stars containing remnants of previous generations. are 2% metal, found in the spiral arms.