galaxies Flashcards
4/9/24 (45 cards)
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
