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62 Cards in this Set

  • Front
  • Back
Bok Gobules
dark nebulae with well defined reigons
*layer above the Chromosphere
*observed during solar eclipses
*radiates strongest in x-rays
collapsing cloud of gas and dust which will eventually become a star
*layer above the photosphere
*radiates in Hydrogen Balmer lines (emmision spectrum)
HH Objects
*formed when the gas and dust in a protostar forms a disk, jets of energy are emitted, and these jets excite ISM
*evidence that stars are forming
Solar Wind
*gas that follows magnetic filed lines
*when the magnetic field lines break apart,the gas streams out in a solar wind
*coronal holes are the source
Interstellar Reddening
the process in which dust scatters blue light out of starlight and makes stars look redder
*layer closest to the sun
*low density
*where sunspots are observed
Brown Dawrf
star whose mass is too low to ignite nuclear fusion and is heated by contraction
Roche Lobe
volume within a Roche surface which is gravatationally associated with one of hte stars
T-Tauri Stars
not yet main sequence stars, located near birthline
Event Horizon
the boundary of a black hole from which no radiation may escape
Emission Nebulae
ionized by nearby hot stars and emit an emission spectrum
Mass Transfer
when the mass from one star in a binary system transfers its mass to the other star
Apparent Visual Magnitude
the visual magnitude of a star as it appears from Earth
Accretion Disks
whirling disk of gas that forms around a compact object such as a white dawrf, neurton star, or black hole as matter is drawn in
Nuclear Fusion
lighter nuceli combine to create heavier nuceli, releasing energy in the process
material blown off by a star that is the companion of a white dawrf
Zeeman Effect
*splitting of emission lines of sunspots due to presence of a magnetic field
*magnetic field prohibits rising gas from delivering heat to the surface
X-Ray Bursters
an object that produces repeated bursts of xrays
Differential Rotation
when different parts of a body have different periods of rotation
Triple Alpha Process
3 He nuceli=1 Carbon nucleus
Proton-Proton Chain
set of three reactions which convert 4 Hydrogen nuceli into one He nucleus
beams of light given off
Absolute Visual Magnitude
*brightness of a star if it is 10pc or closer
*if we know the distance to a star and the apparent magnitude, the actual magnitude can be determined
Roche surface
defines a reigon in which matter will be gravatationally bound to one star or hte other
Stellar Masses
center of mass and orbital period velocity tell us the mass
Degenerate Matter
*gas so dense electrons aren't free to change their energy
*matter almost solid but wont compress like a solid
Spectral Line Broadening
*main sequence stars because they are smaller than other stars, cause a broadening of spectral lines
Planetary Nebulae
expanded shell of gas ejected from a star during hte latter stages of its evolution
Visual Binary Systems
*two stars whose orbits can be mapped out
*line between the stars always passes the same center of mass
Schwartschild Radius
the distances that defines the event horizon
Solar Flares
*when the magnetic filed lines become too twisted, they cancel each other out and reconnect
*stored energy is released as photons and charged particles
Supernova Reminants
shall moves outward and interacts with ISM
Apparent Brightness
*measures the lumonsity of a star
*how bright a star looks as seen by the human eye
*changes with distance
Giant Star Evolution
Star expands, temperature decreases, lumonsity increases
Reflection Nebulae
clouds that scatter light from nearby cooler stars
absorbtion and reemission of photons
Cause of Sunspots
magnetic filed are dragged around the sun and where they tangle, sunspots occur
Supernova Explosions
*iron forms in the core and reactions stop
*core collapeses
*core increases in temp
*all layers collape
Stellar Radii
can be found if we know lumonsity and temperature of a star
Hydrogen Shell Fusion
H2 in the core heats up, fusion takes place, uses up H2
Distance Modulus
*the difference between the apparent and absolute magnitude of a star
*a measure of how far it is away
CNO Cycle
series of reactions involving C2, N2, O2, and 4H2 nuceli comebind to create one He nucleus
Hydrogen Fusion
*at high enough temperature and pressure, 4 Hydrogen protons can fuse into a He nucleus and mass converts to energy
Red Dwarf
*little gravity, dont need many nuclear reactions to balance it
*never evolve into a giant becuase temperature wont get high enough
Spectroscopic Parallax
the meathod of determing a stars distance by comparing its apparent magnitude with its absolute magnitude as estimated from its spectrum
Black Dawrf
*Carbon and Oxygen
*what is left after heat is radiated away
hot ionized gas trapped in magnetic field lines
Helium Flash
explosive ignition of He fusion in the core of Giant Stars
Inverse Square Law of Light
if one light is twice as far away as the other, it will appear 1/4th as bright
Neutron Stars
*supernova protons combine with electons and create neutrons
*gravity is halted by neutron pressure
*the rising of hot fluid and sinking of cool fluids (convection)
Helium Core Fusion
core continues to shrink, core heats up so He can fuse
*cooler, dark reigons on the Sun
*can last up to 2 months
*dark spot-umbra
*lighter spot surrounding-penumbra
*position and number change over time
*22 yrs=full cycle, polarity flips every 11 yrs
White Dawrf
*hot, small objects
*what is left after outter layers blow off
*no more fusion can occur
Dark Nebulae
clouds that block background light
Intrinsic Brightness
measure of the total amound of light a star emits
Absolute Lumonsity
*the amound of energy a star gives off in every direction
*if we know the apparent brightness of a star and the distance, we can determine the lumonsity
*measures distance of a star
*only the parallax of the closest stars can be measured
Spectroscopic Binary Systems
*as the stars circle their orbits, the spectral lines move together
*spectral lines shift and then merge
a measure of the flow of energy out of a surface