galaxies Flashcards
4/9/24
a collection of dust, gas, and billions of stars bound together by their mutual gravitational attraction
galaxy
- very little interstellar dust and gas
- little star formation
- subdivided by the galaxy’s roundness
elliptical galaxies “E”
- central bulge with arms
- active star formation
- subdivided by size of central bulge and how tightly wrapped the arms are
spiral galaxies “S”
- central bulge is stretched out to form a bar shape in the center
- active star formation
- subdivided by size of central bulge and how tightly wrapped the arms are
barred spiral galaxies “SB”
- disk galaxy with no arms
- between elliptical and spiral galaxies
- very little star formation
lenticular galaxies
- very rich in dust and gas
- has star formation
- no real shape
irregular galaxies
- unusual shape, size, and composition
- interacting galaxies or active galactic nuclei
- colliding galaxies resulting in starburst areas (rapid star formation)
peculiar galaxies
a) youngest star(our sun)
b) high metallicity
c) formed from nebulae that were rich in heavy elements
Population I Stars
a) middle aged stars
b) intermediate metallicity
c) formed from the gas and dust released by dying population III stars
Population II Stars
a) oldest stars(came first)
b) low metallicity
c) formed from hydrogen and helium in the early universe
Population III Stars
clusters of galaxies held together by gravitational force and dark matter
Galaxy clusters
1,000 or more galaxies
Rich clusters
few dozen to 100 galaxies
poor clusters
almost spherical shape with a central concentration of galaxies
regular clusters
random or asymmetrical distribution of galaxies
irregular clusters
- area of galaxy clusters
- held together by some gravitational force but mostly DARK MATTER
superclusters
- largest supercluster found so far
- 520 million light years in diameter
- astronomers have found 8,000+ galaxies surrounding the milky way
laniakea supercluster
- center of laniakea supercluster
- creates a gravitational anomaly due to other superclusters moving towards the great attractor rather than away from it
great attractor
what’s our cosmic address?
1) Earth
2) Solar System
3) Interstellar Neighborhood
4) Milky Way Galaxy
5) Local Galactic Group
6) Virgo Supercluster
7) Local Supercluster Laniakea Supercluster
8) Observable Universe
what galaxy do we live in?
milky way
Suppose a radio telescope is pointed towards our nearest galactic neighbor, the Andromeda Galaxy. Describe
how we could turn this data into an image that we can see with our eyes?
Use radio data to create a false-color image
A Cepheid variable is a type of star that is used to measure distances. What did Hubble discover using this type
of star?
Discovered that the universe is expanding and that tgere are other individual galaxies
The most common system for categorizing galaxies categorizes them by their ________________, was developed
by _______________________________ and is sometimes called “Hubble’s ___________________________”.
shape
hubble
Hubble’s tuning fork diagram
Do galaxy mergers happen very often?
yes
Has the Milky Way ever merged with other galaxies?
yes
Is it likely that the Milky Way will merge with any galaxies in the future?
yes
Will the stars in the Milky Way galaxy ever burn out?
yes
Describe these subgroups of ELLIPTICAL galaxies:
- e0
perfectly spherical
Describe these subgroups of ELLIPTICAL galaxies:
- e3
flattened and elongated
Describe these subgroups of ELLIPTICAL galaxies:
- e7
very elongated and cigar-shaped
Describe these subgroups of SPIRAL galaxies:
*Sa
large central bulge, tightly wound arms
Describe these subgroups of SPIRAL galaxies:
*Sb
medium central bulge, moderately wound arms
Describe these subgroups of SPIRAL galaxies:
*Sc
small central bulge, loosely wound arms
Describe these subgroups of BARRED SPIRAL galaxies:
*SBa
large central bar, tightly wound arms
Describe these subgroups of BARRED SPIRAL galaxies:
*SBb
medium central bar, moderately wound arms
Describe these subgroups of BARRED SPIRAL galaxies:
*SBc
small central bar, loosely wound arms
What is the name of the galaxy cluster that the Milky Way is in?
local group
Our galaxy is ______________________ly across by _____________________ ly thick.
100,000 ly across
2,000 ly thick
How many stars does our galaxy contain?
300 billion
The center of our galaxy is a galactic _______________ which contains a _________________ called
_____________________, and also ____________________ of stars
center: galactic nucleus
contains: supermassive black hole and
millions of stars
Surrounding the nucleus of our galaxy is a flattened sphere of stars called the
central/galactic bulge
What is the name of the Milky Way arm our Sun is located in?
orion arm
The ______________ extends in a sphere around our galaxy and contains dark ___________________
halo
dark
Where in our galaxy are we located?
the outer edge
What is Milkdromeda?
the collision of the galaxies the Milky Way and Andromeda
