Chapter 16 Part A ( up to 413)(Karly's 15) Flashcards
Types of Galaxies
Irregular, Spiral, Elliptical
of the three galaxies these are redder
Elliptical
contain more cool gas and dust and interspersed with hot ionized gas
Spiral
What causes the different colours of galaxies
Types of stars
Why do Spiral and Elliptical galaxies appear white
have all kinds of stars
A dwarf galaxy has less than
less than a billion stars
A giant galaxy has more than
a trillion stars
Why is the halo of a spiral galaxy hard to see
because halo stars are dim and spread over a large volume of space
Example of a spiral galaxy
Milky way
Disk stars include stars of ..
all ages and masses
Halo stars are
old and low in mass
Galaxy disks always contain_________medium but the proportions of _______,atomic and _____________gas differ from galaxy to galaxy
Galaxy disks always containINTERSTELLAR medium but the proportions of MOLECULAR ,atomic and IONIZED gas differ from galaxy to galaxy
The halo component of the spiral galaxy includes
the halo and central bulge
Major difference between elliptical and spiral galaxy
elliptical do not have a disk
Do Elliptical Galaxies have a lot of cool gas?
nope - that is usually in disks where stars are a forming
Most common type of Galaxies in the universe
dwarf spheroidal galaxies
classification for larger magellanic clouds or galaxies which appear to be in dissarray
irregular galaxies
irregular galaxies are most common…This tells us they were more common when..
among distant galaxies and as such were more common when the universe was younger
Elliptical Galaxies are noted with an E and a corresponding number. The larger the number, the…
An E0 galaxy is a-
- the flatter the elliptical galaxy
- sphere
SB denotes what kind of Galaxy
Spherical- barred galaxy
Sa denotes a….
SBc denotes a…
Spherical galaxy with a large bulge …lol
Spherical barred galaxy with a smaller bulge than the Sa. llololollol
Spiral Galaxies tend to congregate in small…
groups of a few dozen
Elliptical Galaxies tend to be found in …..which may contain
clusters which may contain 100’s of thousands of galaxies
Why do galaxies differ?
Spin, Density, Collisions
Why would spin alter the shape of a galaxy?
amount of angular momentum of a protogalactic cloud could determine size of resulting disk
Why would Density of the protogalactic cloud impact shape of galaxy?
Elliptical galaxies could come from
dense protogalactic clouds that were able to
cool and form stars before gas settled into a
disk.
What may explain why elliptical galaxy’s are found in large clusters?
evidence of a supercomputer’s representation of two spiral galaxies colliding and formatting an elliptical galaxy
Hubble’s constant tells
us age of universe because
it relates velocities and distances of all galaxies
The cosmological horizon or maximum look back time is
14 billion years
- If the center of a
galaxy is unusually bright
(~100-1000 LMWG) we call it an…
2.The most luminous are called…
-active galactic
nucleus (AGN).
-Quasars are the
most luminous
examples of
AGNs!
Parallax is the _______ ________ in a star’s position as __________ orbits _ _______. Measuring distance using Parallax requires knowing the ….
Parallax is the APPARENT SHIFT in a star’s position as EARTH orbits THE SUN.Measuring distance using Parallax requires knowing the .PRECISE SUN-EARTH DISTANCE OR AU.
Speed of radio waves
speed of light
We can determine distance by measuring….and applying the inverse square law for light
We can measure distance by measuring the APPARENT BRIGHTNESS OF AN OBJECT WHOSE LUMINOSITY WE ALREADY KNOW and applying the inverse square law for light
Our sun is a main-sequence star with a spectral type of
G2
a standard candle is a
light source of a known luminosity
The more certain we are of about a objects true luminosity, the more certain we are of
its distance
Main sequence fitting is one of the most important techniques for measuring distance. It relies on..
comparisons of main sequence stars on the HR Diagram that we already know the distance of, to clusters we dont
The most useful standard candles are ______ _______ ________because we can determine a Cepheid ‘s luminosity from the …
Cepheid Variable Stars because we can determine a Cepheid ‘s luminosity from the period between its peaks of brightness
White dwarf supernovae are useful for measuring___________ distances because they are __________and all have the same ______ _________.
White dwarf supernovae are useful for measuring LARGE distances because they are BRIGHT and all have the same PEAK LUMINOSITY.
When Hubble proved the Andromeda Galaxy WAS NOT inside the Milky way (using _______ _______) he proved that the Milky way was…
When Hubble proved the Andromeda Galaxy WAS NOT inside the Milky way (using CEPHEID VARIABLES) he proved that the Milky way was…merely one of many galaxies
A galaxy’s red shift tells us…
how fast it is moving away from us
The relationship between __________ and __________ tells us the universe is expanding
The relationship between REDSHIFT and DISTANCE tells us the universe is expanding
CHAPTER 15 IS
HELLA LONG… : ( I’MA MAKE IT TWO SECTIONS
