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What makes a star a star? It's a . . . |
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Definition
big bag of gas (plasma), with nuclear fusion reactions in the core
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the sun is held up against self-gravity by
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The chemical composition of the Sun is most similar to that of
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| Mass m is a form of energy E |
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What kinds of particles fuse in fusion reactions?
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Definition
| protons, as well as other atomic nuclei |
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Term
When hydrogen fusion takes place, some of the ____ of the original ____ gets converted to ____.
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Definition
| mass, protons, energy (light) |
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The Sun's energy is derived from... |
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Definition
| fusion of hydrogen to helium in its core |
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| Dark, relatively cool patches on the Sun where magnetic fields have suppressed heat flow from the interior |
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Most of the brightest stars we see at night appear bright because
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Definition
| they are intrinsically very luminous but much further than the closest stars |
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Measuring stellar parallax is important because |
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Definition
a parallax allows the direct determination of a stellar
distance |
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A nearby star's parallax _angle_ is accurately measured by Earthlings and Jupiterlings. How do their observed parallax angles compare?
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Definition
| the Jupiterlings find a larger parallax angle |
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A nearby star's parallax _angle_ is accurately measured by Earthlings and Venusians. How do their observed parallax angles compare?
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Definition
the Earthlings find a larger parallax angle
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Binary stars are essential in determining what stellar property?
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Stars with cooler surface temperatures than the Sun but are much more luminous (intrinsically) must be
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_____ stars provide most of the total mass in stars;
_____ stars provide most of the light from stars.
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| low mass stars....massive and giant |
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Term
The stellar property that is most important in determining
how quickly a star will evolve is a star's |
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When stars burn hydrogen on the main sequence, the fusion reactions occur
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Presently, low mass stars burn Hydrogen via the ____ while high mass stars use the _____.
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Definition
proton-proton chain ... CNO cycle
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Term
How did the first generation of high mass stars burn hydrogen?
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Definition
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The Sun is about ____ & is about ____ its life on the main sequence
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Definition
| 5 billion years old, half way through |
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Term
After the nuclear fuel has been used up in the core of a star, the core then _____ and ____.
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What element is produced in helium burning?
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Definition
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Hydrogen fusion in stars occurs at _____ helium fusion
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Definition
| a much lower temperature than |
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Term
The stellar remnant (corpse) of a star like the Sun is a
white dwarf |
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Definition
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Term
Supernovae are particularly important to us because
much of the material that the Earth & we humans are made of was expelled from
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Definition
| stellar interiors by supernovae |
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Term
Will our Sun ever undergo a white dwarf supernova?
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Definition
no, our Sun is not in a close binary star system
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Term
When a star becomes a black hole, where does the star's mass go?
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Definition
the mass compresses to a singularity at the center
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Term
What kind of pressure holds up a black hole?
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Definition
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Term
If the Sun were somehow turned into a black hole of the same mass...
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Definition
| our orbit would stay the same, safely distant from the black hole |
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Term
If you were inside the event horizon of a black hole and aimed a flashlight outward, away from the center of the black hole, we on the outside would see your light
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Definition
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Term
If you were inside the event horizon of a black hole, could you see out of it?
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Definition
| Yes, photons from outside still pass through the event horizon |
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Term
the solar cycle marked by the appeareneand dissaperanse of sunspots is cause by
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Definition
| the growth and decay of magnietic fields |
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Term
stars with biggest luminosity Masses
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Definition
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white dwarfs are not on main line sequence and are at |
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Definition
the bottom A
Giants at top! C |
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Term
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Definition
| huge balls of burning gas that emit light from far away distance |
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| what is defining characteristic of stars |
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Definition
| nuclear fusion in the core of star--FUSION |
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| how does the sun hold itself up against self-gravity |
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Definition
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Term
how is the sun structured? what are its atmospheric layers?
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Definition
| photoshpere, chromosphere, cornoa |
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Term
| what is the chemical composition of the sun and how does it compare to those of the planets? |
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Definition
| hy he +gases - like jovian planets |
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Term
| what fusion reaction is teh sun using primarily and where |
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Definition
| nuclear fusion , dense core |
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Term
| what was teh solar neutrino "problem" |
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Definition
| a lot on earch seen 1/3 expected- turned into 2 other kinds . we found 3 |
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Term
| what are sunspots and why are they relatively dark |
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Definition
| dark spots in photosphere, darker becuase they are cooler. very magnetic |
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| what drives teh solar activty cycle |
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Definition
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| how do we determine basic stellar properties such as surface temperature, chemacal composition, luminosity, mass , siz and velocity? |
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Definition
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| how do we measure distances to stars |
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Definition
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| direct determination of steller distance- shift |
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| are the britest stars in the night sky just closer to us or far away and unusually luminous |
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Definition
closer- brigher ( size, distance, luminosity)
farther away- could mean more luminous
Depends? |
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Term
| how does suns luminosity compare to other stars |
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Definition
| average star compared to others |
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| what does e=mc^2 mean and how is it relevant to the fusion process |
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Definition
Mass m is form of energy E.
stars create their own energy through fusion |
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Term
| why does fusion requre extremely high temperatures and densities |
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Definition
| very small go fast - high temps |
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Term
| what kinds of particles fuse in fusion reactions? |
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Definition
| protons, as well as other atomic nuclei hy he carbon |
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Term
| how do fusion reactions produce engergy |
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Definition
| join 2 nuclei to single nuclei - release energy |
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Term
| where do fusion reactions occur in a star? |
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Definition
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Term
| how do stars fuse hydrogen, helium, carbon, etc? |
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Definition
hy: proton-proton chain CNO cycle
He: trople alpha (2 step)
cabon: alpaha (capture) |
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Term
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Definition
| cold dense clouds, gravitationally contracting and fragmenting |
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| which stars are most numerous, which provide the most mass, which generate the most light |
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Definition
numerous- more low mass stars than high mass stars
most massive most mass from low mass stars
most lifht most light from high mass and giant stars |
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| how old is the sun and when will it start to die |
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Definition
| 5 billion and die at 10 billion |
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Term
| what stellar property determines how quickley a star evolves and dies? |
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Definition
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| how does the temperature for helium fusion compare to that for hydrogen fusion |
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Definition
| he required more energy bc fusing only 2 He = unstable beryllium |
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Term
| where are heavy elements like oxygen, calcium and iron made? |
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Definition
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how do stars die? what are the threee kinds of stellar corpes?
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Definition
from same way its born , it dies, as nuclear fusion process takes place each atom slams into each other not only producing that energy but the 2 atoms that smah turn into one atom/ heavier/ it turns from Hy to a heavy element. the heavier the more heat is produced to fuse them (elements). depending on the mass of the star it can continue the neculear process all the way to the element that absorbs energy so the nuclear process ends there for majority of the stars. the stars core wil try to fuse iron but fail and stars expand and BOOM = supernovae
luminosity dermines how star dies
1. white dwarf+planetary nebula: many buring stages but short of core Fe - buring
2. neturon star + supernova II : many burning stages, ending with core Fe- buring implosion
3. Black hole: same as 2^. but outer star smothers SN and Fe core grows too massive for NS |
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Term
| what happens to a star if it tries to fuse iron in its core? |
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Definition
| iron coreimplosion- neutron state |
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Term
| what will the Sun become when it dies? what will most stars end up as? |
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Definition
| white dwarf--> black holes (red giant) |
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Term
| how do lifetimes of stars compare to the current age of the universe? |
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Definition
| I DONT KNOW. age of universe ?? |
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Term
| how can stars evolution be affected by being in close stellar binary system |
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Definition
transfer mass to each other
type II single Masses star iron core
collapse---> leaves NS remnant youn stellar pops |
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Term
| what kinds of stars blow up in supernovae? what do these explosions leave behind? |
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Definition
type 1
accrcting WD in binary star system explodes old stellar population
?? idk |
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Term
| how does the structure of a star change when it dies? |
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Definition
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Term
| what is a planetary nebula? |
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Definition
gas cloud puffed out off unstable star
cor shrinks and becomes white dwarf |
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Term
| what do Hertzprung-Russell diagrams plot? why are they useful? |
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Definition
plot steller temp v luminosity
know things about star by knowing temperature |
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Term
| what is the physical signifiance of the "main sequence" of a hertzprung-Russell diagram? |
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Definition
age luminousity distance clolor
"spetroscopiz parallax" |
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Term
| what other stellar properties apart from those expliity plotted can be deduced from the diagrams? |
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Definition
color age distance
spectroscopiz |
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Term
| how are the mass and luminosity of main swquence stars related ? |
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Definition
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Term
| what is the relative size of a star which is cooler than the sun but it more luminous? |
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Definition
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| what is the physical signifiance of the "main swquence turnoff" |
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Definition
tells the age of the most massive star on sequence
*orion - lower left is sirus B |
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Term
what is a white dwarf? how does a white dwarf form |
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Definition
the stellar remnant of a star like the sun
(corpse)
stopped contracting, stopped fusion reactions- expand to red giant and shrink and die
so small not much light |
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Term
| how big in size is white dwarf? whats its maximum mass |
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Definition
diameter= 1 earth diam
mass <1.4 M sun |
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Term
what is the ultimate fate of an isolatedd white dwarf
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Definition
| will cool forever -> black dwarf (none old enough yet) |
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Term
| what happens to a WD if its mass is pushed ober its mass limit? |
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Definition
will explode - core collaspe
neutron stars |
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Term
| will our sun ever undergo a white dwarf supernova? |
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Definition
no our sun is not in a close binary star system
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Term
| what is a neutron star? how do they form |
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Definition
remnant of core collapse supernova
most gigantic "atomic nuclei" |
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Term
| what kind of pressure holds up a nuetron star? |
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Definition
Neutron degerency pressure
-not strong force |
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Term
| what is the mazimum mass of a neutron star? |
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Definition
3-3.25 masses 1.472.3 M
??
AHH |
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Term
| what happens if you add mass t oa neutron star near its mass limit? |
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Definition
| expands and then blows up into supernova |
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Term
| how big in size is a neutron star? |
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Definition
small city 10 km in diam
very compact |
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Term
how do we detect netron stars?
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Definition
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Term
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Definition
A celestial object, thought to be a rapidly rotating neutron star, that emits regular pulses of radio waves and other electromagnetic radiation at rates of up to one thousand pulses per second.
--says google |
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Term
| what are black holes? what are their basic properties? |
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Definition
surrounded by even horizon
nothing can escape not even light= black
-collapse star with strong gravity- pull fields that even light cannot escape^. massive gravity |
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Term
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Definition
| dying of giant stars - gravatiy forces matter to crush until singularity(core of bh) is created |
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Term
| what holds up a black hole against self gravity |
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Definition
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Term
| what is the even horizon of a black hole? how does its size related to the mass of a black hole? |
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Definition
"the point of no return" i.e. the point at which the gravitational pull becomes so great as to make escape impossible. Light emitted from beyond the horizon can never reach the observer. any object approaching the horizon from the observer's side appears to slow down and never quite pass through the horizon, with its image becoming more and more redshifted as time elapses.
When people talk about the size of a black hole, they are referring to the size of the event horizon. The more mass the singularity has, the larger the event horizon. |
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Term
| when a star becomes a black holewhere doesthe star's mass go? |
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Definition
| mass compresses to a singularity at center core |
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Term
| how do we detect black holes? |
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Definition
how they influence gavity and light
1 star orbiting something invisible
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Term
| what is the maximum mass of a black hole? |
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Definition
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Term
| what happens to to the appearence of an object as it falls into a black hole? |
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Definition
| blueshifted.. events happen faster bc sense of time is faster |
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Term
| can you see out of a black hole |
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Definition
| yes photons from outside pass through event horizon |
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Term
| if sun turns into black hole, same mass |
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Definition
| our orbit would stay the same, safely distant from the black hole |
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Term
| where are stars with larger diameteres |
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Definition
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Term
| where are stars with shortest life time on main sequence? |
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Definition
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Term
| where do stars have shortest life? |
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Definition
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Definition
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Term
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Definition
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high maginitude =
low maginitdue = |
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Definition
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the bigger stars are born the faster they die.
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Definition
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Term
| if main sequence is yellow it is older than a blue cluster |
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Definition
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| Neutron stars and black holes have____. (element) |
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Definition
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Term
orion is in lower left
sirius b white
closest dwarf |
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Definition
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