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What is the Sun's photosphere?
The innermost region of the suns atmosphere with a
density of 0.01% of the air we breathe
Why can we only see one layer of the Suns atmosphere?
The upper two layers are nearly transparent to most
wavelengths of visible light, so we see straight through them to the photosphere
Where is the photosphere darkest?
At the limb, the edge
How do gases move in granules and why?
Hot gases move up in the center of each granule and
cooler gases cascade down word around its edges; this is caused by convection
Hotter regions emit more photons per square meter then
do cooler regions; this is why the centers of the granules are brighter than the edges
What is the chromosphere?
A region of less dense stellar gas above the photosphere We also discuss several other topics like What are the three domains of symptoms of adhd?
What are spicules?
Jets of gas in the chromosphere
Outermost region of the suns atmosphere
Transition zone If you want to learn more check out What are the three reasons why ad slopes down?
Between the chromosphere and Corona in which the
temperature skyrockets to about 1million K
What are the two mechanisms that heat the Corona?
First, energy is carried and released there by the suns
magnetic fields. Second, jets of very hot gas are sent up from the chromosphere into the Corona
When can the chromosphere and corona be seen?
When there's an eclipse or with special telescopes
What is solar wind?
Gas that is moving fast enough to escape the suns
How long is the sunspot cycle?
The equatorial regions rotate more rapidly than the polar regions
The splitting of a single spectral line into two or more lines Plasma
A mixture of electrically charged ions and electrons
The study of the sun's interior by recording vibrations
What is the solar cycle and how long is it?
22 years and the time it takes solar magnetic fields to If you want to learn more check out Define industrial city 1875-1920.
return to their original orientation
Magnetic dynamo model
The sun's magnetic field was created as a result of the
sun’s rotation and the resulting motion of the ionized particles found throughout it If you want to learn more check out What are the four key elements of diabolical witches?
Brighter, hotter areas of the chromosphere
Darker, cooler; act as conduits for gases to flow out of the sun
What happens when a coronal hole faces the earth?
The solar wind in our direction increases dramatically
What do solar flares do?
Release vast quantities of high-energy particles, as well as x-rays and ultraviolet radiation
Coronal Mass Ejections
Huge loop, canopy, or balloon shaped volumes of high
energy gas being ejected from the Corona
The process of using nuclei at such extreme temperatures Hydrogen fusion
The conversion of hydrogen to helium
What is solar luminosity and how is it produced?
The total energy output per second; to produce this
luminosity the sun converts 600 million metric tons of hydrogen into helium within its core each second
What does the solar model say?
Begins with the inward force due the suns gravity. This
force increases the pressure and temperature in the suns core causing hydrogen fusion. Because the sun is not shrinking there must be an outward force that counters the inward force of gravity If you want to learn more check out What is nicolaus copernicus known work?
The balance between the inward force of gravity and the
outward force from the motion of the hot gas
Where is the radiative zone?
Extends from the core to about 70% of the way out to the photosphere
A flash of light emitted when an electron goes through
stellar parallaxWe also discuss several other topics like What are the two kinds of conventional terms?
the apparent motion of nearby stars among the
background of more distant stars due to Earth's orbit
brightness of stars as seen from Earth; denoted by m
negative versus positive apparent magnitude
negative apparent magnitude is brighter than a positive
denoted by M; how bright a star actually is at 10 pc
inverse square law
the rule for how quickly the brightness of an object
changes with distance
how we determine the peak of a star's blackbody spectra
of a star's spectrum; tells us its surface temperature
what are Balmer lines?
visible hydrogen lines
why were some of the A-P categories dropped?
because the Balmer lines can be weak whether it is hot or cool
how are spectral types further broken up?
each spectral type is broken up into 10 temperature
subranges and these are further indicated by 0 (hottest) through 9 (coolest)
to the right of the main sequence; bright but cool
a little cooler than giants
bigger and more luminous than giants
hot, dim, tiny remnants of stars; the size of Earth
supergiant luminosity class
Ia and Ib
giant luminosity classes
II, III, and IV
main sequence luminosity class
what luminosity class is the sun?
method of determining distances between stars
what is the common error amount in spectroscopic parallax 10%
binary stars that lie in the same direction, so they look like a single star
both stars can be seen in the pair
the formula for the sum of the masses
the cube of the semi-major axis divided by the square of
center of mass
the common point that the binary stars orbit
which star is closer to the center of mass?
the more massive one
binary stars that produce spectral lines that shift back and forth
spectroscopic binaries' lines
most often only a single set of lines can be seen instead of double
matter between stars
how much mass does the interstellar medium contain?
10% of the mass in our galaxy
what is the interstellar medium composed of?
gas containing atoms and molecules and tiny pieces of
why does the interstellar medium glow?
scattered light from stars in the area
bluish haze, starlight scattered from the interstellar gas
dense region of interstellar gas and dust
larger bodies of gas and dust that nebulae are in bedded in molecular clouds
darkening of light by intervening gas and dust
an object appears redder than it actually is when we see it through visible wavelengths through the interstellar medium
are regions of interstellar gas and dust that are dense to
prevent most visible light from getting to us
regions of interstellar gas and dust that glow from energy
they get from nearby stars, exploding stars, and collisions between nebulae
how have we been able to discover distant stars that are obscured by the interstellar medium?
the objects also emit radio or infrared photons that are
scattered relatively little on their way to us
ashes of dead star; have a distinctly arched appearance
what causes supernova remnants to glow?
collides with preexisting matter exciting the electrons and molecules
how does a star form from supernova remnants?
when the shell of the supernova rams into a giant
molecular cloud with enough speed it compresses the cloud causing it to become Jeans Unstable, causing the birth of a star
small regions of the giant molecular cloud become jeans
unstable making them denser and darker, the dark regions are called Bok globules
why can protostars not be seen in visible light?
they are enshrouded by their outer layer of gas and dust
pre-main-sequence stars that do not have enough
gravitational force that heat their cores immensely, so they contract to planetlike orbs of hydrogen and helium
gas-ejecting stars in spectral classes G and cooler
Herbig Haro objects (HHO)
the jets from T-Tauri stars slam into interstellar gas causing it to glow and creating HHO
H II regions
nebulae that are predominantly ionized hydrogen
collection of hot, O and B stars that produce the ionizing
when do stars appear on the main sequence?
it depends on their mass
zero-age main sequence (ZAMS)
set of locations on the H-R diagram where pre-main
sequence stars first become stable objects - neither shrinking nor expanding
main sequence stars and equilibrium
main sequence stars are the stars in hydrostatic
will higher mass stars shine longer?
no; they burn more fuel more quickly than low mass stars
lowest-mass main sequence stars; masses between 0.08M 0.4M; fully convective stars
hydrogen shell fusion
hydrogen rich gas outside of the core is compressed inward and heated enough to begin helium fusion
Pauli exclusion principle
nature does not allow two identical particles to exist at the same time and at the same place
exclusion principle and helium fusion
as helium electrons are pushed together, the exclusion
principle forces many of them to move faster so they do not become identical
electron degeneracy pressure
cores of low mass giants are supported by this; electrons in the exclusion principle are called degenerate, and keeping the
electrons apart provides pressure that keeps the core from collapsing
what temperature does helium fusion begin?
100 million K
when the core temperature and the fusion rate increase
triple alpha process
dominant process for fusing helium in the core of giants; 3 helium atoms fuse to become carbon atom
what are the two steps of triple alpha process?
two helium nuclei fuse to create beryllium, which either
carbon is formed or the beryllium turns back into helium; if carbon fuses with helium, it produces oxygen
the region between the main sequence and the right side
where stars have begun helium fusion and expand
how can variable stars be identified?
their changes in brightness in a field of stars with constant luminosity
RR Lyrae variables
stars that are post-helium flash that pass through the lower end of the instability strip as they move horizontally on the H-R diagram
brightens and fades because the star's outer layers expand and contract
type 1 cepheids
brighter, more massive, metal-rich stars
type 2 cepheids
dimmer, lower mass, metal-poor stars
gravitationally bound groups of old stars from which few
horizontal branch stars
hot stars less than 2M fusing helium in their cores
surviving portion of the main sequence that are just
beginning to exhaust the hydrogen in their cores
population I stars
open clusters that formed from the debris of older metal
population II stars
formed from older metal-poor stars
the region surrounding binary stars; takes on a figure 8
Roche lobs and mass
the more massive star is always in the larger lobe
when two stars are so far apart they live life cycles as if
they were isolated and single
when two stars are close, and one overflows is Roche lobe contact binary
when both stars completely fill their Roche lobes, because they touch and exchange gas; not as common
more common than contact; they overflow their lobes
giving rise to a common atmospheric envelope
asymptotic giant branch star (AGB)
once helium shell fusion begins and the energy pushes the outer envelope of the star and it leaves the horizontal branch and ascends
the core is showing, the expanding gas and dust is
considered to be a
does a white dwarf have an atmosphere?
yes, a thin layer of hydrogen and helium
how does a nova occur?
occur in close binary systems that contains white dwarfs
the star deposits energy into; once the temperature increases enough hydrogen fusion ignites and blows it into space; the explosion is the nova
the limit of the amount of mass a white dwarf can have
type Ia supernova
semidetached white dwarfs that blow apart completely
what causes a supernova?
a companion star dumps gas onto a white dwarf causing it to cross the Chandrasekhar line
process of converting low-mass elements into higher-mass elements
new shells in the star
each stage of fusion adds a new shell of matter onto the
core which push the outer layers further out until the star is a supergiant
silicon fusion in high-mass stars
the end product is iron, which then leads to the death of
gamma-ray photons breaking apart the iron nuclei
type II supernova
happens in higher mass stars
(primary) cosmic waves
high speed particles from supernovae aka photons
secondary cosmic waves
cosmic rays created from atoms in our atmosphere
cores stay intact as highly compressed clumps of neutrons neutron degeneracy pressure
when neutrons are pressed together they start to move
rapidly and produce a pressure greater than the electron
how fast do pulsars rotate?
30 times every second
when do pulsars slow down?
when they get older
combining the two magnetic fields of the neutron star; also called soft gamma ray repeaters (SGR)
rotating radio transients
emission from neutron stars, it releases radio and other
material in which electricity and heat flow without friction
material in which electricity and heat flow without the
system of losing energy
an isolated pulsar radiates energy causing it to slow down so its solid surface changes shape, which then causes a jump in the angular momentum - this causes a glitch in the rate at which the pulsar is slowing down
emits x-rays at a low level and all of the sudden an abrupt increase occurs
why do x-ray bursters occur?
like novae, they occur because of their companion neutron star
theory of special relativity
description of how motion affects our measurements of
distance, time, energy, and mass
2 notions of theory of special relativity
1. your description of physical reality is the same
regardless of the constant velocity at which you move; 2.
regardless of your speed or direction you always measure the speed of light to be the same
theory of general relativity
describes how spacetime changes shape in the presence of matter
spacetime and gravitational force
the curvature creates an attraction between all matter
in creating a black hole, matter compresses to infinite
best-known nascent theory for singularity
the boundary between a black hole and the rest of the
the distance from the center of the black hole to the event horizon
when a stellar remnant collapses into a black hole it loses all of its internal magnetic field, the field's energy is released as this
gravitational radiation travels as ripples in spacetime
what are the 3 properties matter keeps after entering a black hole? mass, angular momentum, and electric charges
2 types of black holes?
those that rotate (Kerr) and those that don't
swirling region of space
when does a black hole have the most effect on you?
when you are very close to the event horizon
entering a black hole and coming out somewhere else
nothing can leave a region of space that contains a
how do we know black holes exist?
their effects on the orbits of other stars and gas
where are most intermediate-mass black holes located?
in globular clusters
rotating stars with at least 20 M with strong magnetic fields and stellar winds
process of black holes converting their mass into energy Hawing process
the energy from inside the black hole is transmitted
outside the event horizon as gravitational radiation to replace energy taken away from newly formed particles
result of Hawing process
the black hole losses its mass and evaporates