stars and galaxies exam vocab

Core

1. Suns innermost layer, source of energy and heat

2. 15 MillionK

3. Density: 160

4. Luminosity= the surface luminosity

Radiative Zone

2nd layer of suns interior, energy is transported by radiation

it takes hundreds of thousands of years to traverse due to opacity

Convective Zone

3rd layer of suns interior, energy is transported by ?

rising hot bubbles reach the photosphere and cause granulation

Photosphere

4th layer of the sun, innermost layer of atmosphere

Chromosphere

5th layer of the sun, middle layer of the suns atmosphere. Emission spectrum, ragged upper transition layer

Corona

6th layer of the suns atmosphere, contains 9 prominences. very low density, high temperatures, contains 2 spectra- F Corona(scattered photospheric light) and K Corona(hot electrons radiating a continuous spectrum)

Hydrostatic Equillibrium

The sun is in a state of balance called ___________. The outward flow of energy created an outward pressure trying to expand the sun, while gravity pulls inwards. Since the sun isnt expanding or contracting, then these forces are balanced. This balance determines the size of the sun.

Energy Flow, Luminosity

________ is the rate of energy produced inside of the sun, it is exactly the same as the Sun’s _________ at the Sun’s surface.

increase

If the sun were radiating MORE energy than it radiates away at the surface, then it would have to ________ in size and temperature

decrease

If the sun were generating LESS energy inside than it radiates at the surface, then it would have to ________ in size and temperature.

Granulation

The top of the convective zone is the surface and it has a mottled look called ___________, which is due to the bright centers of the bubbles cause by the hot riding gas and surrounded by darker regions where the cooler, denser gas is going down into the lower convective zone

Photosphere

99% of the light we see comes from this suns layer

Absorption Spectrum

The light from the sun starts as a continuous spectrum, or a rainbow, but as it travels through the suns cooler photosphere, some colors are sucked out, leaving dark lines. The result is a gapped rainbow that we call the ___________

Chromosphere, transition zone

The ___________ starts at the coolest point in the Sun’s atmosphere and extends upwards until the temperature rises rapidly into the ___________. The reason for the rapid climb in temperature is likely magnetic heating in the upper layers.

Spicules

_________ are narrow jets of hot gas shooting upwards from the photosphere into the chromosphere likely due to magnetic fields.

Corona

The sun’s ___________ can be seen during an eclipse

Helium Flash

• As a star ascends the Red Giant Branch, its He core becomes degenerate. When the Triple Alpha process ignites, a sudden burst of energy causes core expansion and stabilizes luminosity temporarily.

Horizontal Branch

after a helium flash, the star burns helium stably into carbon. the star becomes a source of stellar winds, and variable stars such as RR Lyrae emerge

Asymptotic Giant Branch

This phase is characterized by mass loss and pulsations. with increasing carbon ash, the star climbs a second red giant branch, more massive stars commence, burning heavier elements (up until iron)

s-process nucleosynthesis

This slow process produces elements heavier than iron. in massive agb stars, neutrons freed by nuclear reactions enable neutron capture on iron nuclei

RR-Lyrae Stars

population 2, on the Horizontal Branch exhibiting regular oscillations, often older with lower metallicity

Cepheid Variables

High mass AGB stars (pop 1&2) with strong period luminosity relation for measuring cosmic differences

White dwarf

below the Chandrekhar Limit (1.4 solar masses) supported by electron degeneracy pressure, composed of carbon and oxygen from helium burning

neutron stars

massive cores collapse further

Black Holes

the most massive cores collapse without any force stopping gravity

Bigger

Moving UP on the HR Diagram means going to a ________ diameter stars bc the only way that luminosity can increase if the temperature is  is constant is if the surface area increases

Bigger

Moving to the right on the HR Diagram means there is going to be a ______ diameter becuase the only way luminosity may remain constant when the temperature is decreasing is if the surface area of the star increases

Temperature vs Luminosity

The Hertzprung-Russel diagram is a plot of __________

Temperature, hot to cold

On the HR diagram _________ is on the x-axis, and it runs ____________.

Luminosity

On the HR-Diagram, ________ is on the y axis, the higher the star is plotted, the greater this is.

composition, Mass

The 2 things that dtermine the position of a star on the HR diagram are

Population 1 stars

heavy stars with high element abundances (above 0.5%)

Population 2 stars

stars with low element abundances (less than 0.1%)

1

The sun is a population ___ star, as are most nearby stars in the milky way.

down, up, weak

the pp reaction changes the ____ quark into an ____ quark, a flavor changing reaction, it must be a _____ interaction.

consumes

the pp reaction ______ energy because the neutron is more massive than the proton

pp-reaction

4 hydrogen atoms (=2 protons and 2 neutrons) collide within the suns core and merge in a chain reaction that creates helium. the leftover energy created in the collision is released as light and heat, according to e=mc²

Chandrasekhar Limit

1.4 solar masses

White Dwarf

If the residual core mass is less than the Chandrasekhar Limit , then the core is held up against gravity by electron degeneracy and it becomes a _____ ______.

Special Relativity

(einstein, 1905) deals with relative motion and the relationship between time and space,There is no special, absolute rest stop in the universe. If you are floating in space and another person zips past you, there's no way to say who is "really" moving and who is "really" standing still. All constant motion is relative.The speed of light ($c \approx 300,000 \text{ km/s}$) is the ultimate speed limit of the universe, and it is constant for every observer. Time slows down for a faster moving object. Incompatible with quantum mechanics.

General Relativity

(Einstein 1916) Gravity id a result of the curvature of space-time. It describes gravity as being due to a warping of geometry of space time rather than it being a separate force (special relativity) Energy causes space time to become curved by its presence. Light would be bent by gravity.

same

he speed of light in a vacuum will appear the ______ for all observers, independent of their frame of reference.

Postulate 2

the speed of light is always the same.

The equivalence principle

The feeling of being pulled by gravity is exactly the same as the feeling of being pushed by a uniform acceleration.

Einstein proposed that these two things are fundamentally equivalent (the same), so we can't tell them apart locally.

Red Shift

as light moves up in a gravitational field, it experiences a __ _____, so it loses energy, NOT speed.

Event Horizon

the ________ is a point of no return around a black hole, it is a boundary where the gravity becomes so strong that the escape velocity is greater than the speed of light. Things cannot ever escape a black hole once they are inside of it.

stops

Time appears to _____ at the event horizon, objects dropped appear to smash up flat and never get in

inversely

The temperature of a black hole is _____ proportional to the mass

Black hole

If the residual core exceeds 3.4 solar masses, the mass will slip below the schwarzschild radius and a ____ ____ will result

schwarzschild radius

the distance from a non-rotating black hole's center to its event horizon. This radius depends solely on the object's mass

differential rotation

the sun rotates faster at its equator than the poles

field lines

flares are caused by twisted ____ ____.

Prominences

_______are loops that reach the chromosphere and corona along which photospheric material arches up along the field lines.

Fermions, Bosons

_________ obey the Pauli exclusion principle, while _____ do not

half, whole

fermions have a ____ integral spin, bosons have a _____ integral spin.

Bosons

force carriers

Gluons

A type of boson: force carriers that hold nuclei together and quarks (tiny particles (think Glue)

photons

Type of Boson: electromagnetic force carriers, couple to electric charge, gets weaker with the square of the distance

W and Z bosons

the force carriers of the weak force: incredibly heavy and weak, short distance

boson

is gravity a boson or a fermion?

Quarks

possess color, can feel the strong force

supernova, neutron star

When the residual mass is between 1.4-3.4, it will collapse creating a _________ when protons and electrons can form neutrons and neutrinos. The reminant is a _______ ____, which is stabilized againt further collapse by neutron degeneracy.

expand, Post main sequence stage

The formation and contraction of a pure helium core causes the star to ______ at first. This is the ____ ______ __________ _______.

Triple alpha process

When the envelope becomes convective, the H brought down causes a rapid rise in luminosity until the helium core finally ignites the _____ ______ _______ burning helium into carbon in the helium flash.

envelope, Cepheid Variables, distance

The stars on the AGB are subject to ______ ejections which form planetary nebulae and in some cases go through variable star phases. _______ ________ are an example and have period-luminosity relationship that is useful as a _______ measuring tool.

postulate 1

the laws of physics are independent of the observers frame of reference

Space Time Diagram

this diagram depicts the limitations of relativity

not a force

according to general relativity, gravity is _____.

energy

space time is curved by the presence of _____

space time

light moves in straight lines, straight lines are bent in a curved _____ _____.

neutron star

When the mass of a star's core is greater than 1.4 times the mass of the Sun, degenerate electrons can't keep it stable as a white dwarf. Instead, it becomes a _____.

nucleus of an atom

a neutron star is as dense as the _____ __ __ _____.

supernova

after the core of a star becomes a neutron star, the rest of the stars material explodes into a ________.

Chandrasekhar

the astrophysicist who first calculated the highest mass that a dying star can have and still be a white dwarf

neutrinos

when supernovae explode they give off a large amount of light. But in the observations of supernova 1987(In the large megellanic cloud) it showed that the supernova gives off more energy in the form of _______.

low, high

the corona has very ____ density and ____ temperatures

K, F

_-corona are hot electrons radiating through a continuous spectrum

_-corona are scattered photospheric light

Solar wind

_____ ____ moves outward through coronal holes

11, 22

every __  years the magnetic field is wound up and inverts itself, giving rise to a net __ years

coronal mass ejections

cause high fluxes of particles

Sunspot, magnetic field

The ______ cycle is caused by the winding up of the sun’s _____ _____.

further, closer

Sunspots occur ____ from the suns equator in the early cycle and _____ towards the end of the cycle

Leptons

are colorless, cannot feel the strong force

weak-force

quarks possess color and can feel the strong force. all generations are conserved except in _______ interractions