Astronomy Flashcards
Karl Schwarzschild
-radius at which a stat would become “dark”
John Michell
- a large enough mass in a small enough space would result in a dark star
- escape velocity > c
Georges LeMaitre
- father of Big Bang theory
- backwards thinking
- universe originated at one point
- packed in a very small point
Event horizon
How close you can get before light can’t escape
What’s inside the event horizon?
Newton: very dense mass
Relativity: Spacetime collapses to a singularity
Closest star to earth
Proxima Centauri
Most common stars
Red dwarf
Low atmospheric pressure is what type of star
Giant
Sun spectral class
G2
False colour image
An image in visible light so we can see it
Brown dwarf
Failed star
- low temp
- like Jupiter
- star w/o fusion
Solar cycle
- 11 years
- solar max/min
- driven by magnetic field
- variation in solar activity
Pulsar
- fast spin
- forces charged particles to travel magnetic field
- neutron star
General relativity
Gravity = acceleration
-Spacetime + curves/dips
Special relativity
Speed of light is constant
Everything else adjusts (time dilation and length contraction)
Blue straggler
Young blue star in old globular cluster
Binary star
Pair of stars orbiting each other
Globular cluster
Blob of stars close together
Cepheid variable stars
- change brightness
- gas pressure builds up = star expands
- pressure released = star contracts
Speed of light in a vacuum
300 000km/s
Type 1a supernova
- white dwarf sucks H (g) from companion
- gains so much mass its unstable
- explodes
Proof of Big Bang theory
CMB
Abundance of H, He, Li
Universe is expanding (hubble’s law)
Structure of universe and galaxies
Hubble’s law
All galaxies are moving away from us
Farthest galaxies are moving the fastest
Big Bang theory
Universe originated at a single point
Black holes
Singularity
Event horizon
Light can’t escape
Singularity
Point of infinite density
-maybe stopped with quantum mechanics
Fusion (main sequence)
H-> He
Medium mass star life
Nebula Blue giant Main sequence ~10 billion years~ Red giant White dwarf + planetary nebula Black dwarf (theory)
Giant star life
Nebula Blue giant ~10 million years~ (H, He, C, O, Si, Fe) BOOM -neutron star -black hole
Dwarf star life
Nebula Blue giant Red dwarf ~100 billion years~ White dwarf Black dwarf (theory)
How do we know how old the universe is?
- Radioisotopes (half lives)
2. Nuclear fusion (know what should be there, compare to what’s actually there)
Parsec (in LY)
3.258LY
Parallax
ApParent shift in position because earth moves
Farther = smaller parallax
1 LY in km
- 5x10^12
9. 5 trillion
1 AU in km
1.495x10^8
150 million
Triangulation
Shorter distance
Use trig
Doppler effect
Redshift = farther
Blueshift = closer
You know why
Hertzsprung-Russell diagram
Y axis: bright - dim (top-bottom) X axis: O B A F G K M (left-right) \ is main sequence Top right is red Giants Bottom middle are white dwarfs
Spectral classification
O B A F G K M
O: 50 000K
M: 3000K
+ # from 1-9
Star properties: colour
Indicates TEMP
Blue = hot
Red = cool
Determined by energy
Wien’s law
- Objects at different temps emit spectra that peak at different wavelengths
- Hotter objects radiate more at any wavelength
Hot: emit most at short wavelength (blue)
Cool: emit most at long wavelength (red)
Blackbody
Kirchoff
- don’t emit energy
- don’t reflect light
- light observed is emitted (glow in the dark ish?)
Stars energy is determined by
Size
Age
Rate of fusion
Absorption spectra
When a gas cloud intercepts light and scatters certain colours
Identifies elements
Less light goes straight so these colours are darker lines
Emission spectra
When a gas is energized
Gas only emits certain colours
Identifies elements
Spectroscopy
How we study stars
Line spectra
Spectrograph
Splits energy given off by a star into components
Apparent magnitude
How bright a star is from earth
Low # = high magnitude
Sun: -25
Faintest: +25
Absolute magnitude
Depends on:
- How much light it emits
- How far from earth
Sun: magnitude 5
‘True’ brightness
-luminosity
-how far from 32.6LY (10 parsecs)
Luminosity
Total amount of energy radiated/s
Star properties: categories of size/mass
Dwarf (8/100 sun)
Medium mass (sun)
Giant/supergiant (5-150x sun)
Radio waves (wavelength and energy)
Long wavelength
Least energy
Radio waves discoveries
- magnetic fields
- radio signals
- inferometry (2 telescopes make a good pic)
- plasma clouds
- quasars discovered
Infrared (discoveries)
- heat (ex fire)
- passes through gas and dust
- reflected sunlight
- climate change
- changes in land cover
- trees and health of them
- remotes
- night vision
- see not visible stuff
- cooler objects
Ultraviolet (discoveries)
- light from ozone satellites
- young hot stars
- atmosphere
- permanent dark craters
- composition
Cassini: saw composition and aurora’s of Saturn
X-Rays (discoveries)
- supernovae
- X-rays (bones)
- composition
- chemical structures
- hot and enerjetic objects (pulsars)
- temperature
- density
- magnetic fields
- zinc and nickel on Mars
- sun’s corona
What uses infrared
ISO Spitzer (SIRTF) SOFIA James Webb Herschel
What uses X-rays
CHANDRA
RXTE (Rossi)
Suzaku
NuSTAR
What uses radio waves
Very large baseline array (VLBA)
HALCA
VLA
What uses gamma rays
Fermi
SWIFT
CGRO
HESS
Gamma rays (discoveries)
- passes easily through atoms
- radioactive decay
- explosions
- CME’s
- composition of Mars
- pulsars/black holes
- come from top of thunderstorms
- protection for satellites
What uses UV
Hubble
IUE
Astro
GALEX
Stellar black holes
From stars
Supermassive black holes
In centre of galaxies
Much bigger
Event horizon
Point past where nothing can return
Outflow
Spin of magnetic field of gas
Jet
Specific type of outflow
Field line spinning (elongated tubes of plasma)
Frequency
Cycles/s
Hz
Wavelength
Length of wave (crest-crest)
-measures in metres (nm too)
Or angstom
Electromagnetic wave theory
James maxwell
1873
Electro + magnetism
“Light is an electromagnetic wave composed of electric + magnetic field - exerts forces on charged particles”
Red light
700nm
Yellow light
600nm
Blue light
500nm
Violet light
400nm
Which type of spectrum is most useful in the study of stars
Absorption line spectrum
Maxwell was the first to _____
Unite magnetism and electricity
A star that emits most of its radiation in shorter wavelengths is what colour
Blue
In which class of stars would you find the greatest amount of heavier elements
Class M (red)
A main sequence star generates most of its energy by fusing
Hydrogen info helium
Which stars have the shortest lifespan
Supergiants
What type of star may end in a black hole
Supergiant
A protostar becomes a star when it begins to:
Generate energy
What is the speed of light
3.0x10^8 m/s
Binary stars end their life through
Type 1a supernova
As an object gets farther what do the angle measuring to it get closer to?
90