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70 Cards in this Set

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What are Main Sequence Stars?
Any star fusing H to He in its core
What is the composition of a star?
Our sun is 99.8% H & He; and 0.2% "metals"
What are the conditions for fusion?
Extremely high temperature and extremely high pressure
What allows for extremely high temperature?
protons move fast enough to overcome repulsion & collide
What allows for extremely high pressure?
Protons are VERY crowded together which increase the chance of many, many collisions which maintains a lot of energy
What does the mass of a main sequence star effect? Name 6
1. Stellar Radius
2. Core Temp., core pressure
3. Star's luminosity
4. Surface Temp.
5. Stellar lifetime
6. End state of a star
What defines the size of a low mass star?
less than 8 solar masses
Wha is the evolution of a low mass star? 4 steps
1. Stable fusion of H to He
2. Fuel runs out in its core
3. Outer Atm. expands and cools -> red giant
4. outer layers escape
-> hot,dead solar core
-> white dwarf
What is the evolution of a high mass star? 5 Steps
1. MS phase
2. Red Giant
3. Huge temperature in core
-> He fusion -> carbon
Carbon + He -> oxygen
Oxygen + He -> Mg
4. Multiple layers of fusion with many elements & core of iron
5. Core collapses, entire star collapses -> supernova! (star then explodes)
What is the importance of a supernova?
1. Creation of lots of metals
2. Dispersal of metals throughout the region
3. Metals -> planets, moons, asteroids, comets
4. Metals -> Life!
5. Shockwave from a supernova -> creates new stars & solar systems
What is the metals vs. time?
-Big Bang -> only H/He lots of energy
-Originally no planets/no life possible
-Every SN generation -> more metals
-metal content of universe increases over time
What is the age constraint of very old stars?
formed when galaxy was very metal poor -> no planets & few organics
What is the age constraint of very young stars?
not enough time to form planets/life/intelligence
What is the mass constraints for too massive stars?
-very short lifetime
-too luminous (HZ must be further)
-Lots of UV
What is the mass constraints for too low mass stars?
-Very low TOTAL energy emitted -> HZ must be VERY close
-Peak radiation is in IR -> weak energy
What are the 3 types of solar systems?
1. single star
2. binary stars
3. star cluster
What are the characteristics of a single star solar system?
one energy source & one source of gravity
What are the characteristics of a binary star solar system?
-2 energy sources (too much energy for temp. stability)
-2 sources of gravity (danger of unstable orbit, ability to even form the planet)
What are the characteristics of a star cluster solar system?
-many energy sources
-many gravity sources
-can planets even form?
What are the 4 constraints of location in the galaxy?
galactic center, Halo, edge of galactic disc, and glactic disk/spiral arms
What are the characteristics of the galactic center?
-stellar density is way too high
-too many enemy/gravity sources
-huge amounts of x Rays and gamma rays
What are the characteristics of the halo?
-globular clusters
-too many energy/gravity sources
-very old stars-> poor metal content
What are the characteristics of the edge of galactic disc?
very metal poor
What are the characteristics of the galactic disk/spiral arms?
- lots of single stars
- lots of young stars
->good metal content
Sum up the 4 Key Stellar constraints
Age, Mass, Types of solar systems, and location in galaxy
What is the importance of atmosphere?
-Protection from UV/X rays/ Gamma rays
-Greenhouse effect (holds in heat)
-> creates small day/night temp. differences
What are the negative effects of a low mass terrestrial?
-low gravity->weak to hold atm.
-cool interior- no molten core & no magnetosphere & no geology
What are the negative effects of a high mass terrestrial?
-Stronger gravity ->atm. becomes too thick
-Strong gravity -> higher chance of collision by comet/asteroid
-Interior is "too hot"
-> too much geology - too much source of CO2 -> atm. too thick
-Strong gravity -> planet can retain Hydrogen which leads to potential production of NH3 & CH4 ->these chemicals may be posionous to life
What is the range of mass for a habitable terrestrial?
.93 Earth Masses < MC 1.33 Earth Masses
How does the HZ relate to the habitbaility of a terrestrial?
the HZ is a region in the vicinity of a star where temp. are such that H2O, if it exists, will be in liquid form
How does the HZ relate to a more luminous star?
HZ is further away
How does the HZ relate to a less luminous star?
HZ is closer
How does slow rotation speed effect a planets habitability?
Weak magnetic field & large day/night temp. differences
What are the consequences of a very close HZ?
-if star/planet are very close & with large gravity/tides, planets rotation is slowed to "synchronous rotation"
-day side is always day -> too hot
night side always night -> too cold
What is the effect of a large Jovian (jupiter)?
-sweeps up lots planetary debris -> fewer impacts on Earth
What is the effect of our moon?
-some objects hit moon, not us
-moons gravity stabilizes Earth's tilt at 23.5 degrees
-> maintains seasons as pretty constant
Sum up the 6 major Terrestrial Habitability charcteristics
Atmosphere, mass, HZ, Rotation speed, large jovian,
moon
What are the 3 categories for planet forming materials?
1. Gases
2. Ices/Volatiles
3. Rocks/Metals
What are the characteristics for gases?
Like H/He they are very abundant and are never solid
What are the characteristics for ices/volatiles?
Like H20/CO2/NH3/CH4 they are somewhat abundant and are only solic at low temps
What are the characteristics for Rocks/Metals?
Like iron/Si/Al they are not abundant and are always solid unless the temp. is VERY high
What are the characteristics of the Extreme inner solar system?
1. few tenths of an AU from the Sun
2. Temp is > 2000K
3. H/He; Ices/Volatiles; & Rocks/Minerals are all gaseous
4. Planets cannot form here
What are the characteristics of the inner solar system?
1. .35-3 AU
2. temps range from hot->medium->warm
3. gases and ices are still gaseous but rocks/minerals can be solid and can form planets
4. Low abundance: small planets
5. High denstiy b/c they are made of heavy material
What are the characteristics of the Outer solar system?
1. 4 AU & beyond
2. very cold
3. Gases are still gaseuous but ices & rocks/minerals are solid
4. Jovian core is made from R/M & lots of ices -> huge cores
5. Huge plantary cores gather huge atm. of h/he -> enormous mass and low density b/c of h/he composition.
6. ices -> moons & comets
What is the idea of late heavy bombardment?
3.9 million ys. ago the ISS planets were bombarded by many comets from OSS and these impacts deposited H2O & organic chamicals
What are the consequences of a large Jovian?
1. sucks up planetary debris
2. circular orbit: no gravitional influences which could eject another planet into the sun or deep into space
3.Jupiter may have robber Mars of significatn mass during formation
4. Jupiter may have robbed losts os mass from "5th planet" -> asteroid belt!
5. Large jovian -> huge tidal forces ->warm interior of Io/Europa
Sum up the 6 planetary functions
1. Planet forming materials
2. EISS
3. ISS
4. Outer SS
5.Late Heavy Bombardment
6. Consequences of a large Jovian
What are the detection methods of Extra solar planets?
1. Direct Detection
2. Stellar wobble
3. Doppler Shift
4. Planetary occultation (eclipse)
What is direct detection?
to "see" a planet
How does one "see a planet?"
Planets shine by reflected sunlight (visible light) and in this light starts outshing planets by a factor of 250M -> 1 billion times
How does one view an IR star?
these stars outshine by 1000-10000x and IR does not penetrate our atm. easily and makes it almost impossible to resolve
What is stellar wobble?
planet & star orbit around a common cneter-of-mass (barycenter) and the planet causes the star to orbit the barycenter which allows us to see the "wobbling effect"
What is the difference in wobbles from small to large planets?
small planets create a very ting wobble and large planets create a larger wobble. This process is best for finding jovians
What is the doppler shift?
-Spectral lines indicate motion towards->away->towards->away
-Repeating blue shift <-> red shift behavior -> there is a planet
What is the data derived from the doppler shift?
planet mass, oribtal distance, revolution period, orbital shape and orbital inclination
What is planetary occultation?
This occurs only if orbital plance is seen edge-on and everyrime a planet transits we see a small dip in its star's brightness
What are the results of the detection methods?
-150+ extra-solar planets found
What are the results of the detection methods in terms of planet masses?
most are bigger than jupiter and no terrestrials
What are the results of the detection methods in terms of planet orbits?
many jovians with eccentric orbits, orbits within 1 AU of star -> hot jovians
-only 18 jovians found beyond 3 AU
How many multi planet systems have been found?
18
What are the 4 major questions about extrasolar planets?
1. Why are there jovians in ISS or EISS?
2. Why are orbits soo eccentric?
3. Why are there so few multi-planet systems?
4. Could Jovians moons be habitable?
What is the implication to Why are there jovians in ISS or EISS?
1. Jovians probably did form in OSS and migrated and spiraled towards the star after accreting gas/dust.
2. Could this process graveject terrestrial planets?
What is the implication to Why are orbits soo eccentric?
- This could also graveject terrestrials from their orbits
What is the implication to Why are there so few multi-planet systems?
Too small to find or they are gone?
What is the implication to Could Jovians moons be habitable?
Potentially Yes
Film Questions
The Hunt for Alien Worlds Questions
What is the best technique for detecting planets?
detecting wobbling stars
What is the SETI system?
Used to detect radio waves throughout the universe and to listen for oncoming messages
What mission was used ti prove our capabilities of looking at other planets throughout the universe?
The galileo mission
What is the principle of Mediocrity?
1. our sun is 1 of billions of similar stars: not unique
2. Milky way is 1 of millions of galaxies: not unique
3. PLanets form around other stars
4. Spectroscopy proves that chemicals found here are found everywhere
5. Laws of physics/chemistry are universal
6. If life exists here, why not elsewhere?