Final Flashcards
The first person to see that the Milky white band that stretches across the night sky is actually made up of myriad stars
Galileo
In the 1780’s, who started counting stars in 683 regions of the Milky Way and determined that we were in the center?
William Herschel
William Herschel didn’t take into account what when theorizing that earth was in the center of the Galaxy
The gas and dust in the galactic plane that blocks out light from distant stars
Plotted the direction and distances to the star clusters. Studied globular structures, tightly bound clusters of stars, that happened to contain RR Lyrae Type variables which can be used to determine distance to the clusters.
Harlow Shapely
Pulsating stars which have a period-luminosity relationship
RR Lyrae
The period of pulsation of a star depends on the what?
Absolute magnitude
In the 1930’s, ____ discovered interstellar gas and dust
Trumpler
How many stellar populations are there?
2
Contains O and B stars, open clusters, and high metal content
Stellar Population 1
Contains low mass stars, globular clusters, and low metal content
Stellar population 2
The speed along the line-of-sight measured using the Doppler shift of spectral lines
Radial Velocity
The sum of Tangential and Radial Velocities
Space velocity
A point in space that has a velocity equal to the average velocity of all stars including the Sun lying within 100 parsecs of the Sun.
Local Standard of Rest (LSR)
The velocity of the LSR is around ______
230 km/sec
We can measure the speed of objects around the galactic center at different radii, this is called the _________
Galactic rotation curve
What types of waves were used to penetrate through gas and dust in order to study the galactic center?
Gamma-rays and radio waves
Speculated about the diffuse nebula astronomers saw as being “Island Universes” in 1755.
Immanual Kant
Observed spiral structure in some nebula in 1845
Lord Rosse
When did Herschel and son catalogue more than 10,000 nebula?
The 1900’s
Features Harlow Shapely as the champion for the spiral nebula being members of our galaxy while Herber Curtis argued they were isolated star systems. This occurred in 1920
The Great Debate
Used the new 100-inch telescope to observe Cepheid variables in the Andromeda spiral nebula. He determined Andromeda was about 2.25 million light years away
Edwin Hubble
What are the 4 types of galaxies?
- Spiral galaxies
- Barred spirals
- Ellipticals
- Irregulars
Which Galaxy has very little gas and dust
Ellipticals
A way of classifying galaxies, but it is not an evolutionary sequence.
Hubble Tuning Fork diagram
Have no location on the tuning fork diagram
Irregulars
Gravitational density waves caused by gravitational instabilities. As the stars, gas and dust move through a spiral shock location, they get compressed and induce further star formation.
Spiral arms
A plot of rotational speed as a function of distance from the center of the Galaxy. In Keplerian orbits, the rotational speed decreases as you go out, but galaxies rotational curves flatten out suggesting “missing mass”
Rotational curves of Galaxies
Our Galaxy the Milky Way is a member of the
Local group
All galaxies, except those very close to us, are moving toward us. True or false?
False away from us
Hubble found a direct correlation between the distance to the Galaxy and its motion or recessional velocity. This Is called
Hubble’s law
The 4 methods of determining the distances of galaxies.
- The sizes galaxies appear
- The brightness galaxies appear
- The sizes of HII Regions
- Supernovas
Space Telescopes primary mission was to determine reliable values for what?
Hubble’s constant
The universe started as an infinitely small point 15 billion years ago and space and time expanded out, carrying galaxies, gas and dust, along with it
Big Bang theory
Einstein theorized that the universe has 3 possible shapes. What are they
- Spherical
- Flat
- Hyperbolic
What did we recently found to be the universe’s actual shape?
Hyperbolic
There was a time early on when the universe expanded faster than the speed of light. What was this known as?
Inflationary Epoch
What occurs in the Main sequence of the HR Diagram?
stars are converting hydrogen to helium
What is the difference between earth and moon rocks?
Lack of water
Why is Venus toxic?
Global warming
Do jovial planets have strong or weak magnetic fields?
Strong
Thee types of telescopes
- Reflectors
- Refractors
- Radio
Which of the three telescope work best?
Reflectors
The shifting in the spectral line due to motion
Doppler shift
When the moon moves between the sun and the earth
Solar eclipse
When the moon moves in front of the earth’s shadow
Lunar eclipse
What causes seasons?
The tilt in the earth’s axis
How many degrees does the earth tilt
23.5
What purpose do constellations serve as?
Road maps
The distance light travels in one earth year
Light year
