Stars and Cosmology

• 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

• - 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

• - One motor moves it
• - Can't hold very much weight

• - How they track the stars
• - More common now
• - Word- class telescopes use this kind
• - Holds more weight

• - 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
• (moon) o-----O (earth)
• here--------->^

• Planet gets so big that it pulls everything into it.
• No debris or anything are left floating around it

• Mercury (closest to sun)
• Venus
• Earth
• Mars

• - 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)

• - Jupiter (closest to sun)
• - Saturn
• - Uranus
• - Neptune (furthest from sun)

• 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

• - Ceres (largest)
• - Pluto (poor guy was demoted)
• - Eris

• - 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

• - Anything in our solar system that orbits outside the orbit of Neptune
• - Came about when Pluto was demoted

• - 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

• 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

• 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

• Old thinking of how our solar system formed
• Suggest ices settled directly into Jovian planets

• 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

• 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

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 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

• 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

• The core is dense so photons move slowly
• Once to the surface they travel away at the speed of light

5800 Kelvin

• 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 smaller the number, the brighter the object
• The bigger the number, the fainter the object
• 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)

Oh be a fine girl, kiss me like that!