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ASTRO 1 Exam 3
Terms in this set (132)
How many Earth's can fit inside the Sun's volume?
About how much of the total mass of all the objects in the solar system is contained by the Sun alone?
99.9% of the total mass in the solar system
What physical process could generate energy like the Sun's?
How many protons does one hydrogen atom have?
One proton, and the different forms can have one or two neutrons
In the Sun, the proton-proton chain makes 4He, the dominant form of Helium. 4he has..
Two protons because it is helium and two neutrons to make 4 total particles in the nucleus
What is the first step in the P-P chain?
A proton combines with a proton to make hydrogen-2 (Deuterium)
What happened after the first step in the P-P chain?
There was a big burst of energy and the reaction created Hydrogen-2 (Deuterium)
Why was there a big burst of energy after the first step in the P-P chain?
Because the mass of the particles starting the reaction is more than that of the products. Mass is converted to energy via E = m x c2
What is the next step in the P-P chain reaction?
Hydrogen-2 combined with a proton to create Helium-3
What happened after dragging the proton into the box with the Hydrogen-2 in it?
Again radiation/energy is released and we are left with Helium-3
What is the final step in the P-P chain?
Helium-3 combines with Helium-3 to make Helium-4 and two protons
What happens when you drag another Helium-3 into the box?
A burst of energy and Helium-4 is produced, with two protons moving off to the side
What is the general result of the proton-proton chain?
4H > He + energy + other products
The corona of the Sun:
Is visible during a solar eclipse
In the convective zone of the Sun..
Columns of gas rise, cool, and descend
What part of the Sun do we typically see?
In nuclear fusion, energy is produced because..
The mass of the reacting chemicals is larger than the of the products
"Luminosity" refers to ... whereas "brightness" refers to ...
Absolute power output at the source / Apparent output as observed at some distances
After doubling the distance from the light source, the bottom detectors readout ... to about ... the top detectors readout?
Decreased / One quarter
On tripling the distance from the light source, the bottom detectors readout ... to about ... the top detectors readout?
Decreased / One Ninth
Gravitational acceleration is...
Inversely proportional to the square of the distance from an object (1/r2)
How far out would you need to move the bottom detector, next to a 100W bulb, to read the same as the top one at R=1 by the 25 W bulb?
Out to twice the distance (R=2)
I'll get the same detector reading for a 500 W bulb, as you do at R=1 on the 20 W bulb, if I move the lower detector to...
What do you notice?
The objects nearer to me appear to move a lot more than those farther away
When you drag the star farther away from Earth does parallax angle get smaller or larger
Does the parallax angle vary directly with distance, or is it an inverse relation?
The size of the parallax angle is inversely proportional to the distance of the star
You measure the parallax angle of a star to be 0.05 arcseconds. How far away is it?
Star "A" is three times further away from the Sun than Star "B". The parallax angle of Star "B" is...
Three times larger than that of Star A
With a measured parallax angle of 0.747 arcseconds, how far away is Alpha Centauri?
When using different points in the Earth's orbit as baseline for a parallax experiment it is best to do the observations:
6 months apart
One star is four times farther away from another. The parallax angle of the most distant star is:
Four times smaller than that of the nearest star
The parallax angle for the star Hadar is 0.010 arcseconds. How far away is Hadar?
Put one of your thumbs at arm's length in front of your face. Now focus on the background and look through one eye at a time. What do you notice about your thumbs?
It appears to move more when it is closer
Star A is 4 times as luminous as Star B. Star A is 2 times as far away as Star B. Which star appears brighter and by how much?
The stars appear the same brightness
Absorption lines are...
- Produced when photons of specific wavelengths are absorbed by a star's outer layer by the electrons of specific chemical elements
- The cooler a star gets, the more atoms and molecules can hold on to to electrons to create absorption lines
Which one of these do you think the spectrum of the sun looks most like?
The absolute amount of energy a star produces in a second, like the wattage of a lightbulb
The parallax angle for Alpha Centauri is 0.74 arcseconds.. The distance to Alpha Centauri is?
- Distance in parsec equals 1 over the parallax angle in arcseconds
- 1.35 parsecs
- 1 parsec is about 3.26 light years
What spectral type is Proxima Centauri closest to?
Proxima Centauri is in the lower right of the diagram, which corresponds to .... Temperatures and .... Luminosities
Low / Low
Using the parallax angle of 16.7 arcseconds, the distance from our current location at Proxima Centauri to Alpha Centauri AB is about...
Alpha Centauri A has a luminosity of 1.6 suns and a spectral type closest to..
Alpha Centauri B has a luminosity of 0.5 suns and a spectral type closest to...
What is the distance to Barnard's star, with a parallax of 0.56 arcseconds?
What spectral class is Barnard's star?
Sirius B, the white dwarf...
- Is not very luminous and so it appears faint compared to the much more luminous Sirius A
- Sirius B is 1000 times less luminous than Sirius A
Second brightest star in the night sky
As the temperature increases the star moves to the ... on the HR diagram, and it gets ... and ...
Left / Smaller / Bluer
When a star moves up on the HR diagram, it gets
Bigger and the color doesn't change
The nearest stars are
Cooler and less luminous
Brighter stars are more luminous, why could they be either red or blue?
We can't see low luminosity stars when they are farther away, only the high luminosity ones
If the radius of Star A is is twice the radius of Star B, but both have similar temperatures, how do their luminosities compare?
Star A is 4 times as luminous as Star B
The lower left corner of the Hertzsprung-Russell diagram has:
The hottest and least luminous stars
Which of the following has the largest luminosity?
Most massive Main Sequence star
Which of the following is coolest at its surface?
Type K main star sequence
Which star is the closest if all have the same apparent brightness?
Type M main star sequence
Which star is the furthest away if all have the same apparent brightness?
Type O main sequence star
What does main sequence mean?
The curve on the HR diagram where stars of different masses are located while they are converting hydrogen to helium in their cores
A 60 solar mass star has a luminosity of ... times that Sun's luminosity, while a 0.1 solar mass star only has a luminosity of ... times the Sun's luminosity
800,000 / 0.003
The 60 solar mass star has a lifetime of ... while the 0.1 solar mass star has a lifetime of ...
3,400,000 / 2,000,000,000,000
This chart looks like a graph about stars. The vertical axis has the ... and the horizontal axis has the ...
Mass / Time
The sequence of events for the sun-like star is...
Stellar nursery, protostar, sun-like star on main sequence, red giant, planetary nebula, white dwarf
Stars less massive than the Sun will also end their lives as...
What is the brown dwarf they are talking about in the bottom row?
It is an object with mass less than 8 percent of the Sun, which cannot have enough nuclear reactions in its core to be a star
Medium-mass stars end as...
Type II supernova then neutron star
High-mass stars end as...
As stars form they heat up, so in general they move ... on the HR diagram, onto the main sequence when their nuclear fusion "engines" turn on.
- Right to left
- When it runs out of hydrogen in its core, the core contracts and starts to burn helium. The outer layers will swell up and the star becomes a red giant.
When it becomes a red giant, the star...
- Decreases in temperature and increases in luminosity.
- Then it goes through a variable stage
After the variable stage the star...
- Produces a planetary nebula
- The outer layers expand outwards
After the variable stage the core of the sun-like star shrinks and becomes a...
- White dwarf, the size of Earth
And then it fades to become a black dwarf
The most massive stars burn heavier and the heavier elements in the core but that the heaviest thing produced is Iron. Why is that?
- Iron is the most stable nucleus
- Burning Iron would not produce energy
When a star is burning helium in its core and has puffed out its outer layer, it is...
A red giant
The very highest mass stars will end their lives as?
A planetary nebula...
Is the ejected outer layers of a low to intermediate mass star
In a high mass star, why does nuclear burning stop at Iron?
Nuclear reactions involving Iron do not produce energy
What is the density at the center of a black hole?
Why are things torn apart when they near a black hole?
The part of the object closer to the black hole feels a greater force
Which of the following statements is true?
Nothing can travel faster than the speed of light
The event horizon of a black hole is?
The minimum distance from which light can escape
An "onion skin" shell burning structure, with elements up to Iron being produced, develops in...
A star much more massive than the Sun
What is at the center of a planetary nebula?
- The core of the dying star
- Something that will eventually become a white dwarf
How do solar-sized and and smaller stars die? About how large are their remnants?
They become white dwarfs, about the size of Earth
What does not happen when an object approaches a black hole?
It quickly gets sucked in even from a large distance
How can we measure the mass of a black hole?
Measure the speed of an orbit of a star in a binary system with the black hole
The habitable zone around the Sun includes..
Earth, and almost Venus and Mars
What if the sun were 1.2 times its present mass. What planets would be in the habitable zone?
Earth and Mars
Stars the include Mercury in their habitable zone are..
A little less than 0.75 times the mass of the Sun
We thought no lives could survive in the clouds of Venus, but there was one type of life mentioned that could. Did you catch what it was called?
I thought it was really cool that the radiodurans..
Could survive in high levels of radiation that exist on Mars' surface, without our filtering domes
This explained life that could exist in the total darkness and immense pressures in the liquid oceans of Europa. Those were called...
Hydrothermal vent communities
What is the main requirement for a habitable zone?
A star that is twice the mass of our Sun would have a habitable zone that..
Include Mars but not the Earth
A star that is 75 percent the mass of our Sun would have a habitable zone that..
Includes Venus only
What factor is not in the Drake Equation?
Communication lag due to large distances between stars
What does the Drake Equation estimate?
The number of technological civilizations in the Milky Way
What kind of Star would Slurpy's home planet have to be orbiting in order for the planet to be habitable?
- The star must be an M type star to have habitable planets at 0.55 AU
- So were looking for a M star with a planet orbiting it with a small semimajor axis
When were the first extrasolar planets found?
Could those extrasolar planets he discovered support life?
No, they orbit closely around a dead neuron star
Can the planets found soon after extrasolar planets support life?
They found massive planets like Jupiter, but very close to the planet star
The first extrasolar planet found in the habitable zone of its host star was found in..
What kind of telescopes did they use back then?
The most successful early planet finding mission, launched in 2009, was called Kepler
When a planet passes a star as seen from Earth..
- The brightness of the star diminishes for a time
- The tiny dip in brightness means that a planet passed in front of the star
What did you get for the G0 star?
A planet that is 17 Earth radii, with a 5 day orbital period, and a temperature of 1584K - definitely not in the habitable zone
What did you get for the M5 star?
A planet that is about the same radius as Earth, and at 0.27AU - 136K temperature so too cold to be habitable
What did you get for the K5 star?
A planet that is about an Earth mass, at a distance of 0.5 AU, and a temperature of 235K, in the habitable zone
We need a ... type star because we know the planet has an orbit with a semi major axis of 0.55AU and we want the planet to be in the habitable zone. For any other type of star, and orbit at 0.55AU would be ... for life.
M / Too hot
It appears that only one planet is orbiting in this habitable zone
GJ 667 C g
A large luminosity star...
Emits more light than a low luminosity star
If a red giant appears the same brightness as a red main sequence star, which one is further away?
The red giant
The heaviest nuclei of all are formed..
During a supernova explosion
Fill in the blank in the following chemical reaction that occurs in the Sun: Hydrogen-2 + Proton = .... + Energy
Which of the following has the smallest radius?
Why does the main sequence part of a star's life come to an end?
The Hydrogen in the core is exhausted
Which of the following will have the shortest lifetime on the main sequence?
Main sequence star with surface temperature of 20000 K
Many of the brightest 100 stars viewed from Earth are not on the main sequence (even though most stars are) because:
The most luminous stars are giants and super giants that have already finished their main sequence lifetimes
A 2-solar mass main sequence star is at the same distance as a 0.2 solar mass main sequence star. Which star appears brighter?
The 2-solar mass main sequence star appears brighter
The temperature of the photosphere of the sun is closest to...
An estimate of the number of communicating/technological civilizations that we
expect in our Galaxy would have a larger number if ...
The average number of planets that could support life for each star was larger
If the Sun had twice its mass, then which of the planets would be in its habitable zone?
In the transit method of finding extrasolar planets, the distance of the planet from its star is found from:
Kepler's 3rd law using the period of the planet's orbit (how often a transit occurs).
How do astronomers measure the temperature of stars?
By looking at which absorption lines are present in the Star's spectrum
If two stars are the same temperature, how can one be more luminous than the other?
It can have a larger radius
The largest fraction of nearby stars (e.g., within 100 light years) are ...
Red main sequence stars
Which of the stars in the diagram above is the hottest?
D (Top left)
If they were all formed at the same time, which of the stars in the diagram above will live the longest?
B (Bottom Right)
The parallax angle of a nearby star is measured to be 0.02 arcseconds. What is the distance to the star?
Which of the following is the sequence of events for a 40-solar mass star (one of the most massive stars)?
stellar nursery, protostar, blue star on main sequence, Type II supernova, black hole
Star A is 9 times more luminous than Star B. The two stars appear the same brightness. What is true about their distances?
Star A is 3 times farther away than Star B.
In the p-p chain, shown in the above diagram, what particles must be input in order to produce one 4He nucleus?
6 protons, but 2 of them are returned when the 4He is produced
What is the name of the slightly cooler layer of the Sun just outside the photosphere?
How does a star move on the H-R diagram during the period of time it is converting hydrogen to helium in its core?
It remains at a certain point on the main sequence and does not move on the H-R diagram.
If the entire mass of Earth were concentrated in a region the size of a marble, the resulting object would be:
A black hole
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