Stars and Cosmology
Card Set Information
Stars and Cosmology
Physics 105 BSU Stars and Cosmology Astronomy
Flashcards for basic Stars and Cosmo physics class
Deviation of light rays by lenses which causes the images to be blurred.
- Caused by lenses only.
- Causes colors making up the light to focus on different planes so you can see the separate colors.
- Fixed by adding another lens.
The apparent displacement of a celestial body due to the finite speed of light and the motion of the observer with the earth
- Gets worse with larger telescopes that allow you to look at objects more closely
- Use adaptive optics to correct
- a mechanism by which astronomical images are corrected for effects of turbulence in the atmosphere
- Eliminates turbulence
- Can't go over 300x mag without this
- Use a central computer to manage an artificial star test to correct image
LENS is the main light gatherer
- Bends light
- Acts like a prism
Employs a MIRROR as the main light gatherer
- Eyepiece up at top
- Light hits CONCAVE mirror first
- Small optical flat mirror to refocus light and bounce through eyepiece
Cassegrain Telescope (Classical and Ritchey-Chretien)
- CONVEX mirror used to bounce light back through eyepiece
- Only difference from Newtonian is mirror used
- Prefer compact nature of scope. Folds in on self
-Uses lens AND mirror as main light gatherer
- Similar to telephoto lenses
- Twin refracting telescopes
- Makes it so you can see a wider area
- Use the same system for telescopes. Putting them in pairs to get better resolution
German Equatorial Telescope Mount
- One motor moves it
- Can't hold very much weight
Alt- azimuth Telescope Mount
- How they track the stars
- More common now
- Word- class telescopes use this kind
- Holds more weight
Very Large Array Telescopes (VLAs)
- Link telescopes together to work as one
- Began with radio telescopes
- Makes telescopes work as if they were miles in diameter
- Must be large enough to be round
- Must have "cleaned out" orbit
- Center of mass must be contained within boundary of planet
"Cleaned out" orbit
Planet gets so big that it pulls everything into it.
No debris or anything are left floating around it
Terrestrial Planets in our system...
Mercury (closest to sun)
- Solid surface
- High comparative density (to gascous planets)
- Small by comparison and a NiFe core
- Comparatively large
- Low density
- Small FeNi core
- Predominately Hydrogen and Helium (similar makeup as stars.)
- Lie in outer part of OUR solar system (probably not normal for universe)
Jovian planets in our system...
- Jupiter (closest to sun)
- Neptune (furthest from sun)
Minor (Dwarf) Planets
Lacked one or more major criteria so are deemed dwarfs instead.
- all in our system are big enough to be round but some are not round
- originally thought to be broken up planets
Minor planets in our system....
- Ceres (largest)
- Pluto (poor guy was demoted)
- Orbit major or minor planets
- Can be captured by the planet
- Thousands of celestial bodies, probably down to pebble sized
- Orbits between Mars and Jupiter
- Not considered a destroyed planet
- Asteroids are held in Jupiter's orbit
- Ceres is the largest
Trans Neptunian Objects
- Anything in our solar system that orbits outside the orbit of Neptune
- Came about when Pluto was demoted
Kuiper Belt Objects (KBOs)
- Orbits in a donut shape at 50 AU around the sun
- About 20 known and named
- Likely 1000s or millions
A relatively small extraterrestrial body consisting of a frozen mass that travels around the sun in a highly elliptical orbit
- Short period comets <200 years
- Long period comets > 200 years
Spherical leftovers at 50,000 AU in all directions.
- None have been discovered so far but there is strong evidence that they exist
Meteor ("Shooting Star")
A rock from space that is falling to Earth through our atmosphere
- Don't usually hit
- Leftovers from the forming of the solar system
- Usually very small. Ionize while falling and then disintegrate
Meteor (rock) that has landed on Earth
- Earth gains and estimated 2 tons a year from these
- 3 different kinds
Type of meteorite that looks just like aluminum.
It is highly magnetic.
meteorite that is consists mostly of stony matter
Highly prized because they have glass in them
An accretion disc is a structure formed by diffuse material in orbital motion around a central body.
The central body is typically a young star, a protostar, a white dwarf, a neutron star, or a black hole.
Gravity causes material in the disc to spiral inward towards the central body
It is made of a relatively cold gas
Phase 2 of the Solar Nebula Hypothesis
A dense condensation of material that is still in the process of accreting matter to form a star.
Phase 3 of the Solar Nebula Hypothesis
T Tauri (cocoon stage)
The young star will produce strong winds in the T-Tauri stage, named after the prototype star in the constellation Taurus.
These strong winds eject much of the surrounding cocoon gas and dust.
With most of the cocoon gas blown away, the forming star itself becomes visible to the outside for the first time.
Stage 4 of the Solar Nebula Hypothesis
When star gains enough heat that converting H into He begins.
Begin Nuclear fusion
Star spends most of it's life in main sequence
Stage 5 of Solar Nebula Hypothesis
One of a class of bodies that are theorized to have formed the planets after condensing from diffuse matter early in the history of the solar system
Formed from leftovers in the accretion disk
Only about 1 km or so in diameter
The collection of matter, in the process of condensation, from which a planet is formed.
Form from planetissimals. Further on in the process of forming a planet
About 1000km to 2000km in diameter
Becomes rount at 400km
The separation of planetary material according to density
Ices and silicates float to the top
Heavier elements sink to core which becomes molten
Disk Instability Model
Old thinking of how our solar system formed
Suggest ices settled directly into Jovian planets
Binary Star System
A system in which there is enough left over from the solar nebula that a 2nd star forms
Believed that our sun formed in a binary system
An extrasolar planet that orbits a star other than earth's sun
Almost all planets close to parent star
All hot Jupiter's are within Mercury's distance to their parent star
How much a star shifts from a massive planet
- 1st (easiest) way of discovering exoplanets
- Determine the period of the stellar shift the mass and distance is known
- Works well when there is only one planet
- if you have it's period, then you have it's temp, then you have it's color, and know it's mass
Two things appear to intersect from our point of view
Star will fade when a larger planet transits it
2nd (harder) way of discovering exoplanets
Works only if plane of our solar system matches same plane of exoplanet
Disk Instability Model
Jovian planets formed closer to sun
- Had near misses with other planets and got thrown out farther from sun because of gravity
- Possible explanation why our solar system is different that others
How rocks are dated
- dated from when they were last molten
- how we know age of solar system---date meteors, etc.
The solar "surface"
We can see about 400 km into it
It is opaque because it has an extra negative electron, otherwise we'd see a lot further into the sun
refers to the diminishing of intensity in the image of a star as one moves from the center of the image to the edge or "limb" of the image.
occurs as the result of two effects:
The density of the star diminishes as the distance from the center increases
The temperature of the star diminishes as the distance from the center increases.
Result of the rising and falling of hot gas that takes place in the convective zone in the photosphere of the sun
Can be 1000s of miles in diameter
300k cooler than center parts
Middle layer of sun seen only during a total solar eclipse
Much thinner than our atmosphere
Very bright spikes that extend from the Sun into the chromosphere.
Only last about 15 minutes
Outer layer of the sun that extends 1 million km
One millionth as bright as the photosphere
Looks like a halo around the sun---not visible to naked human eye
Energy that escapes from the sun
Composed of electrons from H and He with trace amounts of other elements
The sun ejects over a million tons per day--pretty insignificant amount to sun
Cooler, darker areas that can't penetrate a solar filter
Extremely magnetic (this increases with size)
Consists of Umbra and Penumbra
Obeys the Stefan-Boltzman law----They are .3 or 30% as bright or lum. as photosphere
Darker coolest center of sun spots
Red according to Wein's law
borders the umbra of sun spots
intermediate in temperature
Can be splotchy or filamentary in structure
Orange according to Wein's law
Stephan Boltzman Law
The total energy radiated from a blackbody is proportional to the fourth power of the temperature of the body. Also known as fourth-power law; Stefan's law of radiation
Sunspot (solar) Cycles
Sunspot counts rise and fall on an 11 year cycle
22 years is a total cycle meaning the polarity goes from positive, to negative and back to positive
Caused by differential rotation
relating to sunspot (solar) cycles
High magnetism will split absorption line into three instead of one
Cooler, bright red columns of plasma seen against the dar "sky" off the limb of the sun
Rise up from magnetic sun spots
Sometimes they can connect to other spots if they get strong enough and form loops
Seen on the side of the sun
Same as prominences only seen on the front of the sun--against the brighter photosphere
They appear darker because they are cooler
Solar Flares (CMEs)
CME-Coronal Mass Ejection
Super large prominences
Can loop to connect two sun spots but they are huge
a bright region in the chromosphere of the Sun, typically found in regions of the chromosphere near sunspots
As gases are compressed, the temp will rise.
Works initially, but not in the long run
Pressure of gravity balances with released energy
Balance of gravity created by its mass and outward release of its gas pressure
The sun is in Main sequence when it has achieved this
Thermal reactions in the core of the sun must be transported to the surface.
Too little release and the sun will heat up
Too much release and the sun will cool down
Another method of transportation of energy in sun
Occurs in the inner 25% of the sun
This is the same 25% where nuclear fusion is occurring
Energy radiates out like a radiator
One method of transportation of energy in sun
Vertical swirling, cooler gases sink while heated gases rise
Occurs in the outer 30% of the sun
We can see this happening
How does time effect transportation in the sun?
The core is dense so photons move slowly
Once to the surface they travel away at the speed of light
What is the temperature of the sun?
Subatomic byproducts of nuclear fusion
Theorized for a long time but not able to be detected
Finally detected after 40 yrs
This is how we know there is nuclear fusion going on
The apparent change in the position of a nearby star when observed from Earth due to our planet's yearly orbit around the Sun.
This method allows astronomers to calculate distances to stars that are less than 100 parsecs from Earth.
Formula is d=1/p
Further away, less accurate
One way of measuring the distance of stars
Uses the inverse square law (double the distance, luminosity is 4 times less)
Luminosity is known by color or spectral class, both give it's temperature
Based on a number system developed by Hipparchus, a Greek philosopher in BC times
the number, the
the number, the
Each whole number =2.512 x brighter/dimmer than previous whole number
Unaided human eye can't see past magnitude 6
The brightness of a star as it appears from earth using the magnitude scale
Designated with a "m" (small case)
The apparent magnitude of any star if it were placed at 10pc from Earth using the magnitude scale
Designated with a "M" (upper case)
Mnemonic for Star Temperatures
Oh be a fine girl, kiss me like that!