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AST1002-CH. 13
Evolution of High-Mass Stars
40
Astronomy
Undergraduate 3
11/16/2012

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Term
High-Mass stars
Definition
A star with a main sequence mass greater then about 8 solar masses
Term
Carbon-Nitrogen-Oxygen (CNO) cycle
Definition
one of the ways in which hydrogen is converted to helium (hydrogen burning) in the interiors of main sequence stars
Term
Instability strip
Definition
A region on the H-R diagram containing stars that pulsate with a periodic variation in luminosity
Term
Pulsating variable star
Definition
A variable star that undergoes periodic radial pulsations
Term
Cepheid variable
Definition
An evolved high-mass star with an atmosphere that is pulsating, leading to variability in the star's color and luminosity
Term
Period-luminosity relationship
Definition
The relationship between the period of variability of a pulsating variable star, such as a Cepheid or RR Lyrae variable, and the luminosity of the star. Longer period Cepheid or RR Lyrae variable are more luminous than their shorter-period cousins
Term
RR Lyrae variable
Definition
A variable giant star whose regularly timed pulsations are good predictors of its luminosity. RR Lyrae stars are used for distance measurements to globular clusters
Term
Standard candle
Definition
An object whose luminosity either is known or can be predicted in a distance-independent way, so its brightness can be used to determine its distance via the inverse square law of radiation
Term
Binding energy
Definition
The minimum energy required to separate an atomic nucleus into its component protons an neutrons
Term
(Inside a star)
After __ burning, each stage is progressivley shorter
Definition
helium
Term
Neutrino cooling
Definition
The process in which thermal energy is carried out of the center of a star by neutrinos rather then by electromagnetic radiation or convection
Term
Tyle II supernova
Definition
A supernova explosion in which the degenerate core of an evolved massive star suddenly collapses and rebounds
Term
neutron star
Definition
The neutron-degenerate remnant left behind by a type II supernova
Term
The type II supernova leave behind a ___ core
Definition
neutron-degenerate
Term
X-ray binary
Definition
A binary system in which mass from an evolving star spills over onto a collapsed companion, such as a neutron star or black hole. The material falling in is heated to such high temperatures that it glows brightly in X-rays
Term
Pulsars
Definition
A rapidly rotating neutron star that beams radiation into space in two search-like beams. To a distant observer, the star appears to flash on and off, earning its name
Term
Black Hole
Definition
An object so dense that it escapes velocity exceeds the speed of light; A singularity in spacetime
Term
If a neutron star's mass exceeds __ solar masses, it will collapse into a black hole
Definition
3
Term
Special theory of relativity
Definition
Sometimes referred to as simply special relativity. Einstein's theory explaining how the fact that the speed of light is a constant affects nonaccelerating frames of reference
Term
event
Definition
A particular location in spacetime
Term
Spacetime
Definition
The 4 dimensional continuum in which we live, and which we experience as 3 spatial dimensions plus time
Term
relativistic
Definition
describing physical processes that take place in systems traveling at nearly the speed of light or located in the vicinity of very strong gravitational fields
Term
Special relativity concerns the relations ship between events in __ and __
Definition
space and time
Term
__ and __ together form a four-dimensional spacetime
Definition
space and time
Term
Time dilation
Definition
The relativistic "stretching" of time.
Term
Length contraction
Definition
The relativistic compression of moving objects in the direction of their motion
Term
General theory of relativity
Definition
Sometimes referred to as simply general relativity. Einstein's theory explaining gravity of the distortion of spacetime by massive objects, such that particles travel on the shortest path between 2 events in spacetime. This theory eals with all types of motion
Term
equivalence principle
Definition
The principle stating that there is no difference between a frame of reference that is freely floating through space and one that is freely falling within a gravitational field
Term
falling objects follow __ paths through __ spacetime
Definition
curved
Term
geodesic
Definition
The path an object will follow through spacetime in the absence of external forces
Term
Being stationary in a gravitational field is the same as being in an accelerated ___
Definition
reference frame
Term
___ distorts the geometry of spacetime
Definition
mass
Term
Gravitational lensing
Definition
The bending of light by gravity. can be used to detect extrasolar planets
Term
General relativistic time dilation
Definition
The verified prediction that time passes more slowly in a gravitational field than in the absence of a gravitational field
Term
Gravitational redshift
Definition
The shifting to longer wavelengths of radiation from an object deep within a gravitational well.
Term
Gravitational wave
Definition
A wave in the fabric of spacetime emitted by accelerating masses
Term
Singularity
Definition
The point where a mathematical expression or equation becomes meaningless, such as the denominator of a fraction approaching zero
Term
Schwarzschild radius
Definition
The distance from the center of a nonrotating, spherical black hole at which the escape velocity equals the speed of light
Term
Event horizon
Definition
The effective "surface" of a black hole. Nothing inside this surface--not even light--can escape from the black hole
Term
Hawking radiation
Definition
radiation from a black hole
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