Enceladus – A icy moon of SaturnCourse AnnouncementsAssignmentsPursuit of Artificial Intelligence “Life”Quiz 3 HintsQuiz 3 HintsQuiz 3 HintsFormation Environments in ContextThe Big QuestionCondensation TheoryThe Early Solar NebulaCondensation TheoryCondensation TheoryThe Story of Planet BuildingStory of Planet BuildingAccretion of grains into larger massesStory of Planet BuildingStory of Planet BuildingStory of Planet BuildingStory of Planet BuildingStory of Planet BuildingStory of Planet BuildingHow to determine which is rightClearing the DiskClearing the Disk – Gas and DustClearing the Disk – Small bodiesClearing the Disk – Small bodiesRemoving planetesimals causes LHBModern Models of SS EvolutionEvolution of Planetary OrbitsThe Grand TackThe Nice (“Neese”) ModelModern Evolution of SS ModelsGeneral TimelineEnceladus – A icy moon of SaturnCredit: Cassini Imaging Team/SSI/JPL/ESA/NASACourse Announcements•Quiz 3 will be on Friday, 14 Oct.–Will cover chapters 5 and 6–Some hints todayAssignmentsReading Assignments•No new readingParallel Lectures•No new episodesMastering Astronomy•Chapter 6 Homework[Due Thursday, 13 Oct. at 11:59 PM EDT]Pursuit of Artificial Intelligence “Life”Results from Notecard QComment:•Original “I, Robot” is a series of 9 short stories by Isaac Asimov–Asimov’s Laws of RoboticsN = 202Quiz 3 HintsQuiz 3 will cover Chapter 5 and 6•Know the different parts of the Solar System and roughly how far away each is from the Sun.–Terrestrial planets; Asteroid Belt; Gas Giant Planets; Kuiper Belt; Oort Cloud•Know what Nebular Theory is and how it goes from a general nebula in outer space to the Solar Nebula –How does this explain the orbital direction, rotational direction, and flat, disk-like shape of the Solar System.•Adding to above: Know that Nebular Theory explains the structure of the Solar System and that Condensation Theory [topic for today] explains the chemical/density gradient of the Solar System•Be able to list the planets in order:Example question: Saturn is the _____ planet from the SunQuiz 3 HintsQuiz 3 will cover Chapter 5 and 6•Know the different parts of the Solar System and roughly how far away each is from the Sun.–Terrestrial planets; Asteroid Belt; Gas Giant Planets; Kuiper Belt; Oort Cloud•Know what Nebular Theory is and how it goes from a general nebula in outer space to the Solar Nebula –How does this explain the orbital direction, rotational direction, and flat, disk-like shape of the Solar System.•Adding to above: Know that Nebular Theory explains the structure of the Solar System and that Condensation Theory [topic for today] explains the chemical/density gradient of the Solar System•Be able to list the planets in order:Example question: Saturn is the sixth planet from the SunQuiz 3 HintsQuiz 3 will cover Chapter 5 and 6•Know the different parts of the Solar System and roughly how far away each is from the Sun.–Terrestrial planets; Asteroid Belt; Gas Giant Planets; Kuiper Belt; Oort Cloud•Know what Nebular Theory is and how it goes from a general nebula in outer space to the Solar Nebula –How does this explain the orbital direction, rotational direction, and flat, disk-like shape of the Solar System.•Adding to above: Know that Nebular Theory explains the structure of the Solar System and that Condensation Theory [topic for today] explains the chemical/density gradient of the Solar SystemFormation Environments in ContextRadio ImageESO/AlmaESA/HSTESA/HSTVisible LightVisible LightThe Big QuestionWhere does the stuff to build planets come from?•Where do we get the solid materials that will build our planets?•Evidence suggests that nearly all the dust inherited from the nebular cloud of gas and dust is vaporized (turned into a gas) in the collapse to a disk process•Not much solid material, so how do we get it back, and can that process explain the compositional and density gradient?Condensation TheoryCompositional & Density GradientMetalRockMetalRockIces+GasMetalRockIcesExotic IcesMetalRockMetalRockIces+GasMetalRockIcesExotic IcesAs distance away from the Sun increases, we see the see the same building block materials, but keep adding new ones as we go further out. How can we explain this?Beyond here we start to see WATER ICEBeyond here we start to see WATER ICELow Density MaterialLow Density MaterialHigh Density MaterialHigh Density MaterialThe Early Solar NebulaThings get hot when you compress them•The key is that the early Solar Nebula had a temperature gradient–Inner: Very hot (> 1500 – 2000 K) near the protosun–Inner – Middle: Moderate (~ 273 K) around 3 – 5 AU away or so–Outer:Cold (about 100 – 273 K) further out to about 30 AU–Far Outer: Very cold (< 100 K) in the outer regions (> 30 AU)•This temperature gradient in the disk controlled what solid material could form out of the gas (i.e., condense)This temperature gradient controls what solids will condense out at a given distanceWater can condense when cold enough. The so-called “ICE LINE”Condensation TheoryEnvironment must be colder than condensation temperature in order to form that type of solid grainCondensed materials (solids) are what is available to form planetsThe Ice LineCondensation TheoryBased on the condensation temperatures of various materials, i.e., a Condensation Sequence•Oxides and Metals (Fe) 1700 K•Silicates (Si, O, Al, Mg, Fe) 1200 K•Hydrated silicates (add water) 700 K•Carbonaceous materials (C) 500 K•Ices–Water 273 K–Ammonia 100 K–Methane 45 K–Nitrogen 30 K•Gas: Hydrogen and Helium UncondensedVolatileRefractoryDeceasingCondensationTemperatureTemp. must be below this to condenseThe Story of Planet BuildingNebular Theory + Condensation Theory•Now we have solid materials to build planets out of, and we understand that we have more available materials as we increase in distance–until a certain point where we start running out of materialMetalMetalRock‘High’ T Ices (e.g., water)OrganicsMetalRockIcesOrganicsExotic Ices (Low T Ices)MetalRockBuild Terrestrial PlanetsBuild Gas Giant Cores(the gas comes due to higher massBuild Small Icy Worlds (KBOs)HotCoolWarmColdProto-SunDensity drops, so can’t really form large things1. Condensation of solids: according to the condensation sequence (function of temperature):Chemically, you will form about 2 grains of icy material for every 1 grain of rocky materialInner SS: Metal and Rock
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