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part 3, you really can't do any worse
Terms in this set (153)
The basic fusion reaction through which the Sun produces energy is __________.
4 hydrogen nuclei fuse to make 1 helium nucleus
The energy that is released in the hydrogen fusion reaction comes from
The difference in mass between the four hydrogen nuclei and the single resulting helium nucleus
What two items on the list below are in balance in what we call gravitational equilibrium?
gravity and gas pressure
What two items on the list below are in balance in what we call energy balance?
The energy produced by fusion and the energy released into space
Place the layers of the Sun into the correct order from innermost at left to outermost at right.
Core>Radiation Zone>Convection Zone>Photosphere>Chromosphere>Corona
Rank the layers of the Sun based on their density, from highest to lowest.
core, radiation zone, convection zone,photosphere, chromosphere, corona.
Rank the following layers of the Sun based on their temperature, from highest to lowest.
core, radiation zone, convective zone, photosphere.
All the phenomena of solar activity — including sunspots, flares, coronal mass ejections, and the sunspot cycle — are tied to changes in the Sun's __________.
In which of the following layer(s) of the Sun does nuclear fusion occur?
Which of the following layers of the Sun can be seen with some type of telescope?
corona, chromosphere, and photosphere.
Which of the following changes would cause the fusion rate in the Sun's core to increase?
An increase in the core temperature and A decrease in the core radius.
Which of the following must occur for a star's core to reach equilibrium after an initial change in fusion rate?
If the fusion rate initially increases, then the core expands.If the fusion rate initially decreases, then the core contracts.
What would happen if the fusion rate in the core of the Sun were increased but the core could not expand?
The Sun's core would start to heat up and the rate of fusion would increase even more.
Nuclear fusion of hydrogen into helium occurs in the
Energy moves through the Sun's ______ by means of the rising of hot gas and the falling of cooler gas.
Nearly all the visible light we see from the Sun is emitted from the
Most of the Sun's ultraviolet light is emitted from the narrow layer called the ____ where temperature increases with altitude.
We can see the Sun's ____ most easily during total solar eclipses.
The _________ is the layer of the Sun between its core and convection zone.
the Sun's core temperature naturally stays stable
The energy balance that contributes to the solar thermostat is a balance between __________.
the energy released in the core by fusion and the energy radiated from the Sun's surface into space
-solar flares are most common
-occurs about 11 years after a solar maximum (on average)
-auroras are most likely in Earth's skies
-orbiting satellites are most at risk
-sunspots are most numerous on the Sun
The time when there is the least amount of activity on the sun, occurs about 5 to 6 years after a solar maximum (on average)
Sunspots are cooler than the surrounding solar surface because
strong magnetic fields slow convection and prevent hot plasma from entering the region
visible features of the sun
Photosphere- white light, sunspots and granulation
Chromosphere- Ha and UV, Prominences and flares
Corona- X-rays, solar eclipse, mask on space telescope
The photosphere (surface of the sun)
-Granulation: convection cells, give mottled appearance
-Sunspots- Relatively cooler than the photosphere, site of strong magnetic field, appear and disappear as the surface magnetic field changes
-cooler, then hotter, layer above the photosphere
-prominences and flares: material suspended above the photosphere
Clouds of material suspended above the photosphere by magnetic fields
An eruption of gas from the sun's surface that occurs when the loops in sunspot regions suddenly connect
-very low density, visible during solar eclipses, directly visible from space
-strange emission lines
-solar wind: hot diffuse gas that streams off the sun in all directions
-coronal mass ejection: huge bubbles of gas ejected from the sun, can occur w/and without flares, disrupts the smooth flow of the solar wind
-number sunspots changes over 11 year cycle
-magnetic polarity flips every 11 years
-whole pattern repeats every 22 years
Magnetic Field Reversals
-earth: paleomagnetism, fossil record of magnetic field, field reversals
Why does the sun shine?
nuclear fusion, because its hot
inside the sun- how do we know
- Theory (mathematical/computer models)
-Observation tied to Theory, solar neutrinos, solar vibrations
why does the sun shine? (history)
Why doesn't the Sun collapse?
The sun is in gravitational equilibrium
Forces in Nature
-Strong nuclear force
-Weak nuclear force
- Electromagnetic: light EMR is produced when charged particles are accelerated
nuclear fusion: relevant forces
-Electromagnetism: repulsive and long range
-strong nuclear: attractive but very short range, binds protons together in nucleus, stronger than EM at very small distances
layers inside the sun
-Convection zone: energy transported to photosphere by convection motion of hot plasma
-Radiation: energy transported to Convection one by photons
-core: energy generated by nuclear fusion
Nuclear Fusion Equation
4H1 - He4 + photons + neutrinos
The study of the interior of the sun by the analysis of its modes of vibration.
Surveying the Stars
Measuring the distance to the stars I
-Radar ranging (direct measurement)
- I. Parallax
limiting distance for stellar parallax
- ground based
-first rung, distance ladder
Measuring the distance to the stars II
-II. Spectroscopic Parallax: relate the apparent brightness to distance
-first step, the HR Diagram
the brightness of a star as seen from Earth, total power arriving at a location
The total amount of power emitted by a star/object
the brightness of a star as seen from Earth
The actual brightness of a star
difference between the magnitudes of a star or other object measured in light of two different spectral regions—for example, blue minus visual (B-V) magnitudes. measure Temperature
The difference between the apparent and absolute magnitudes of an object. measure DISTANCE
surface temperatures and absorption lines
Provides an independent and more accurate means to determine surface temperature
Annie Jump Cannon is known for
categorizing stars according to spectral type.
-The sequence of stellar spectral classifications from hottest to coolest stars.
-OBA (bluer, hotter, early types of stars)
-obama became a freaking gangsta kill me
Spectral sequence is
temperature sequence, early theory was that the sequences of elements varied with stellar type
Stars are mostly H and He
A complete classification of a star combines
temperature and luminosity
Stars move around the HR diagram as they age and change their luminosity and surface temperature
steps of HR diagrams
1. observe spectrum
2. classify star, spectral type (OBAFGKM) and then luminosity class (super giants, giants, main sequence, white dwarfs
3. obtain luminosity from diagram
4. observe brightness
5. calculate distance
Lifetime of a star
depends on its mass
Size of a star
determined by mass, stefan-boltzmann law
Luminosity of a star
determined by mass, mass-luminosity relationship
high mass stars- post main sequence
-The invisibility strip
-variable stars, can have very high luminosity
Stars in a cluster formed..
at the same time, and from the same materials
the mass of a star at birth determines its..
Measuring Stellar Masses
-newtons version of keepers 3rd law: need 2 or more objects orbiting a common center of mass
-can be used in binary star systems
-types of binary star systems: visual, spectroscopic, eclipsing
spectroscopic binary system
A star system in which the stars are too close together to be visible separately. We see a single point of light, and only by taking a spectrum can we determine that there are two stars.
eclipsing binary stars
- Two close stars that appear to be a single star varying in brightness
- The variation in brightness is due to one star moving in front or behind the other star
Visual Binary Stars
A binary system in which the two stars are separately visible in a telescope.
binary star system
two stars that orbit each other
-solar stellar thermostat; functions while star is on the main sequence
-gradual brightening of the sun/stars
white dwarfs are
the most common endpoint of stellar evolution, exposed carbon core of a low mass star.
Low mass star life cycle
-protostar, main-sequence star, red giant, planetary nebula, white dwarf
-core hydrogen exhaustion, star moves off MS towards the red giant branch, star isn't fusing helium yet, helium flash, horizontal branch, nuclear burning, star returns to giant region, AGB, planetary nebula,
-H-He fusion in the core, gravitational equilibrium
low mass stars in MS
-convection in outer layers
-radiative transport in core
High Mass stars in MS
-radiative outer layers
-convection in nuclear burning core
Leading theorist in white dwarf stars
Said degenerate electrons can withstand pressures of up to 1.4 solar masses
Main sequence stars up to 4 solar masses can end up as white dwarfs if they lose mass during the red giant and planetary nebula phases
fusion is only
in the core
high mass stars - post main sequence
-core fusion source starts
-when last shell begins to fuse silicon, iron builds up in core
-iron core, core collapses under force of gravity, core decomposes
-star blows apart
-neutron star (supernova remnant)
-black hole could form
ch 18. the bizarre stellar graveyard
low mass individual star evolution, and the low mass binary star evolution
3 criteria governing the life cycle of a star
-mass, mass and mass at birth
-stellar evolution can be altered only if mass is exchanged
-mass exchange binary system
white dwarfs in close binary systems
close enough so that mass can be transferred
white dwarf to nova
-the flaring up of a WD
-WD collapses, temp increases, carbon fusion ignites throughout the core
Type 1 Supernova
-a supernova explosion caused by the collapse of a white dwarf
gamma ray bursts
-short duration:merging of 2 neutron stars, neutron and black hole
-long duration: high mass star collapses
-highly focused directional beam
The event horizon of a black hole is
the boundary around a black whole where the escape velocity = the speed of light
A prediction of Einstein's general theory of relativity. Photons lose energy as they escape the gravitational field of a massive object. Light is redshifted as it leaves the central mass
the apparent slowdown in time for a rapidly moving object
light follows the straightest possible path throughout curved spacetime
Gravitational waves are
ripples in the fabric of space-time
Theory that explains why time runs slower the faster you move.
spacetime and matter
-the distribution of matter (and energy) determines the shape of spacetime
-the shape of spacetime determines how matter moves
compact objects (NS and BS) are unique because
physically possible to get close to the center of a massive object
11 feb, 2016: first detection of gravitational waves
matter distorts spacetime in a manner analogous to how heavy weights distort a rubber sheet
Event horizon (Schwarzschild radius)
bottomless pits in space time, escape velocity= speed of light
small black holes
single star or merger, Large tidal forces near event horizon
large black holes
small tidal forces near event horizon
Finding Black Holes
-mass estimates from orbiting objects
high mass stars are born with masses greater than about
8 solar masses
Einstein's general theory of relativity suggests that gravity is
caused by curvature of spacetime
Einstein's equivalence principle says that
the effects of gravity are exactly equivalent to the effects of acceleration
the number of independent directions in which movement is possible
Newton's theory of gravity and general relativity
Newton's theory of gravity is an approximation to general relativity that works when gravity is relatively weak, but breaks down when gravity is strong.
A star that happens to be hidden behind the Sun might become viewable during a solar eclipse due to the bending of light
Two neutron stars orbiting each other at close distance will gradually spiral in toward each other because they lose orbital energy to
Gravitational lensing occurs because
gravity curves space and light always follows the straightest possible path through space.
Space is different for different observers. Time is different for different observers. Spacetime is the same for everyone.
Which of the following is not relative in the special theory of relativity?
the speed of light
Which of the following must be true of a person who shares the same reference frame as you?
The person must not be moving relative to you
basic premises for the special theory of relativity?
1. The laws of nature are the same for everyone.
2. The speed of light is the same for everyone.
Which of the following statements best describes what is "relative" in the theory of relativity?
The theory says that measurements of motion make sense only when we state what they are measured relative to.
The general theory of relativity deals with the effects of gravity, but the special theory of relativity does not take gravity into account.
18. Degenearcy pressure arises when
subatomic particles are packed as tightly as the laws of quantum mechanics allow
1. in a binary system, can explode as a supernova
2. has no mass greater than 1.4 Msun
3. typically about the size of earth
4.supported by electron degeneracy pressure
1.sometimes appears as pulsar
2.usually has a very strong magnetic field
1. size defined by its schwarzchild radius
2. viewed from afar, time stops at its event horizon
The radius of a white dwarf is determined by
a balance between the inward force of gravity and the outward push of electron degeneracy pressure.
A(n) nova occurs when
hydrogen fusion ignites on the surface of a white dwarf in a binary system.
A(n) massive star supernova occurs when
fusion creates iron in the core of a star.
A white dwarf in a close binary system will explode as a supernova if it gains enough mass to exceed the
white dwarf limit (1.4 solar masses)
A(n) accretion disk consists of
hot, swirling gas captured by a white dwarf (or neutron star or black hole) from a binary companion star.
After a massive-star supernova, what is left behind?
either a neutron star or a black hole
When the core of a star like the Sun uses up its supply of hydrogen for fusion, the core begins to
shrink and heat
Stars that are fusing hydrogen in their cores are
main sequence stars
When it dies, a low-mass star expels a
Stars with masses less than about two solar masses are considered
low mass stars
A star that is expanding (into a subgiant and then a giant) has a(n)
inert helium core
The energy that drives the expansion of a star into a subgiant or red giant comes from
hydrogen shell fusion
The final stage of core fusion in a low-mass star is
long lived stars
- begin their lives with less mass and a smaller amount of hydrogen fuel.
-less luminous during their main-sequence lives.
low mass stars
final corpse is a white dwarf, sun is an example, have longer lifetimes, end life as a planetary nebula
high mass stars
-have higher fusion rate during main sequence life
-late in life fuse carbon into heavier elements
-end life as a supernova
Carbon fusion occurs in high-mass stars but not in low-mass stars because
the cores of low-mass stars never get hot enough for carbon fusion
Which of the following stars will live longest?
1 solar-mass star
Which of the following lists the stages of life for a low-mass star in the correct order?
protostar, main-sequence star, red giant, planetary nebula, white dwarf
the CNO cycle?
a set of steps by which four hydrogen nuclei fuse into one helium nucleus
Why is Supernova 1987A particularly important to astronomers?
It is the nearest supernova to have occurred at a time when we were capable of studying it carefully with telescopes.
Before we can use parallax to measure the distance to a nearby star, we first need to know
the Earth-Sun distance
What is the cause of stellar parallax?
Earth's orbit around the Sun.
is greater for low-mass stars than it is for high-mass stars.
Which two basic factors are most important in determining the current appearance of a star?
its mass and its stage of life
to calculate the masses of stars in a binary system, we must measure their
orbital period and average orbital distance
How did astronomers discover the relationship between spectral type and mass for main sequence stars?
By measuring the masses and spectral types of main-sequence stars in binary systems.
From hottest to coolest, the order of the spectral types of stars is
Our Sun is a star of spectral type _________.
distance from the Sun's center, from greatest to least.
corona, chromosphere, photosphere, convection zone, radiation zone, core
Photons take hundreds of thousands of years to get out of the Sun because
their paths zigzag repeatedly.
Because the plasma is so dense in the Sun's interior, a photon can travel
a fraction of a millimeter before colliding with an electron and deflecting into a new direction.
Which of these layers of the Sun is coolest?
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