SDSU Astronomy 101 Midterm 2 Leonard

electron

negatively charged particle found outside the nucleus

proton

positively charged particle found inside the nucleus

neutron

neutral particle found inside the nucleus

element

kind of atom defined by the number of protons in the nucleus

atom

natures building block

Periodic Table of Elements

A table that classifies elements by their physical and chemical properties; rows are called periods; columns are called groups;

isotope

any two or more forms of atoms of the same element whose atoms all have the same number of protons but different number of neutrons

ion

an atom that has lost or gained one or more electrons

atomic notation

a symbolic method for expressing the composition of an atomic nucleus

apparent brightness

how bright an object appears

luminosity (or power)

The total amount of light emitted by an object each second (unit: Watts)

inverse square law of light propagation

the apparent brightness of an object decreases in proportion to the inverse square of the distance to the object

standard candle

an object of known luminosity

speed of light

300,000 km/s or 186,000 miles/second

reflection

return of light after striking a surface

refraction

bending of light when it passes from one transparent medium to another

dispersion

act of separating the different colors of light through being refracted by different amounts

spectrum

the array of colors obtained when light is dispersed

spectroscopy

the study of spectra

continuous spectrum

a spectrum of light composed of a continuous range of color

ROYGBIV

red, orange, yellow, green, blue, indigo, violet

emission (bright line) spectrum

a pattern of bright lines produced by a low-density gas whose atoms have been "excited"

absorption (dark line) spectrum

a pattern of dark lines superposed on an otherwise continuous spectrum

waves

energy being transported through a medium

medium

a substance through which a wave can travel

frequency

the number of complete wave cycles that pass a point each second measured in waves/seconds

wavelength

distance between two identical points on successive waves

meters/wave

electromagnetic waves

A form of energy that can move through the vacuum of space.

electromagnetic spectrum: gamma, X, ultraviolet, visible, infrared, radio

the whole range of electromagnetic waves from gamma rays to radio waves

H-alpha line

the most prominent spectral feature due to hydrogen at visible wavelengths (6563)

Doppler effect

change in wavelength or frequency due to relative motion of wave source and or detector

blueshift

a shift to shorter wavelengths

redshift

a shift to longer wavelengths

radial velocity

motion towards or away from an observer

exoplanet

plants orbiting stars other than the sun

center of mass

point between two objects about which they both orbit. always closer to the more massive object

arc second

1/3600 of a degree

light curve

a plot showing how the brightness of an object changes with time

exoplanet detection: doppler technique

through periodic motion of a star toward and away from an observer caused by gravitational pull on the star by the planet

exoplanet detection: transit technique

through periodic dimming of a star due to passage of planet in front of it

exoplanet detection: direct technique

through directly imaging them

parallax equation

d = 1/p

d= distance, p= parallax

parsec

3.26 light years

photon

individual particle of light

quantum mechanics

the branch of physics that deals with the structure of atoms and their interactions with light

ionization energy

minimum amount of energy required to remove an electron from an atom in its ground state

sunspot

A region on the Sun's surface that is cooler and darker than the surrounding areas

photosphere

visible surface of a star. the region in a stars atmosphere from which visible light escapes into space

conservation of energy

Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes

E=mc^2

energy=mass

c=speed of light

strong nuclear force

very short range but powerful attractive force that binds nucleons together

thermonuclear reaction

a nuclear reaction that results from encounters between particles that are given high velocities by heating them

antimatter

a type of matter in which each particle is opposite in charge, and certain other properties, to a corresponding particle of the same mass

neutrino

Uncharged elementary particles with very little mass that rarely interact with other particles

neutrino oscillations

the transformation of one neutrino type into another

proton-proton chain formula

see notes

gas pressure

the pressure resulting from the thermal motions of gas particles

radiation pressure

the pressure resulting from the impact of photons on a surface or gas

hydrostatic equilibrium

a state of equilibrium in which the inward pull of gravity in a star is just balanced by the outward forces of gas and radiation pressure

Nucleosynthesis

The building up of heavier elements from lighter ones by nuclear fusion

nuclear fission

the break up of heavier atomic nuclei into two or more lighter ones

interstellar gas

consists mainly of hydrogen

interstellar dust

consists mainly of tiny solid grains in interstellar space

main sequence star

a star that is fusing hydrogen into helium in its core

stellar evolution

the changes in a single stars properties as it ages

red giant star

A star of enormous luminosity (up to 100,000 times that of the Sun) and radius (10-1,000 times that of the Sun)

low mass star

Those stars that are born with less than 8 times the mass of the sun. when fusion ends: after production of the carbon oxygen core

high mass star

Those stars that are born with greater than 8 times the mass of the sun. when fusion ends: Iron (26 protons in nucleus) is produced.

mass loss

the loss of material during the life of a star

planetary nebula

a shell of gas ejected by and expanding away from an extremely hot low-mass star that is nearing the end of its life

binary star

two stars that orbit each other, bound together by gravity

white dwarf

final stage of evolution for low mass stars in which its collapsed to a very small size (initial mass 0.1-8M of sun)

electron degeneracy pressure

A force arising from the laws of quantum mechanics through which closely packed electrons strongly resist further compression

Chandrasekhar limit

the upper limit to the mass of a white dwarf (equals 1.4 times the mass of the Sun)

neutron star

a star of extremely high density composed almost entirely of neutrons

supernova

the explosion of a star with resulting release of a tremendous amount of light

neutron degeneracy pressure

a force arising from the laws of quantum mechanics through which closely packed neutrons very strongly resist further compression

black hole

a completely gravitationally collapsed object; a region of space from which neither matter nor light can escape

neutron bombardment

hitting a stable nucleus with a stream of neutrons

pulsar

a rotating neutron star emitting pulses of radio waves

mass transfer

the transfer of material from one object to another

accretion disk

A disk of matter spiraling in toward the compact object

Thermonuclear (Type Ia) supernova

complete destruction of white dwarf due to a thermonuclear runaway initiated at the center of the star

nova

a star that increases thousands of times in brightness and then fades

SN 1987A

A supernova observed in 1987

core-collapse supernova

a supernova that occurs at the end of a massive star's lifetime when the star's core collapses to high density and the star's outer layers are expelled into space

star (new definition)

an object that during some part of its lifetime derives 100% of its energy from the fusion of hydrogen nuclei (proton) to helium

nuclear fusion

the building up of heavier atomic nuclei from lighter ones