HL Tauri – A planetary system in formationCourse AnnouncementsAssignmentsQuiz 3 HintsQuiz 3 HintsDr. Sean Lindsay’s ResearchAsteroidsMeteoritesCometsComet DustInterplanetary Dust ParticlesInterplanetary Dust ParticlesOur Solar SystemCompositional GradientSolar System Density GradientProperties of Solar SystemProperties of Solar SystemProperties of Solar SystemSolar System Formation TheoryNebular TheoryObservational EvidenceObservational ExamplesFormation 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 BuildingHL Tauri – A planetary system in formationCredit: ALMA(ESO/NAOJ/NRAO)Protoplanetary disk around HL TauriOur Solar System for comparisonCourse Announcements•Current grades on Blackboard–Quiz 1&2; Quiz Avg. (lowest dropped);Exam 1; Current MA Avg.•Five (may be four now) observation EC opportunities this week•Quiz 3 will be on Friday, 14 Oct.–Will cover chapters 5 and 6–Some hints today and more WednesdayAssignmentsReading Assignments•Chapter 6. Sections 6.4 – 6.7[Read by Wednesday, 12 Oct.]Parallel Lectures•CC Astronomy: Episode 9: Intro to Solar System[Watch by Monday, 10 Oct.]Mastering Astronomy•Chapter 6 Homework[Due Thursday, 13 Oct. at 11:59 PM EDT](available on MA by tomorrow)Quiz 3 HintsQuiz 3 will cover Chapter 5 and Chapter 16•What type of telescopes are used in professional astronomy, and why they are preferred.–Reflectors > Refractors•Angular resolution of a telescope is directly proportional to the wavelength of light and inversely proportional to the size (diameter) of the telescope.–Smaller number is better angular resolution! The number tells you how close two points can be next to one another and still be seen as two points.Example Question: If you wanted to study the hot gas in the universe (e.g., gas heated by a supernova), what part of the EM spectrum would be most appropriate to use?A) Radio B) Infrared C) Visible D) X-rayQuiz 3 HintsQuiz 3 will cover Chapter 5 and Chapter 16•What type of telescopes are used in professional astronomy, and why they are preferred.–Reflectors > Refractors•Angular resolution of a telescope is directly proportional to the wavelength of light and inversely proportional to the size (diameter) of the telescope.–Smaller number is better angular resolution! The number tells you how close two points can be next to one another and still be seen as two points.Example Question: If you wanted to study the hot gas in the universe (e.g., gas heated by a supernova), what part of the EM spectrum would be most appropriate to use?A) Radio B) Infrared C) Visible D) X-rayDr. Sean Lindsay’s ResearchBuilding a recipe bookResearch Allegory•Given a few cookie crumbs from an unknown type of cookie (Chocolate chip, sugar, oatmeal raisin,, snickerdoodle, etc.) can I determine the recipe for how to make that cookie?–Need ingredient list (chemical composition)–Need relative amounts of ingredients (mineralogy)–Need baking instructions: how hot and for how long?•In reality, it’s not just crumbs from one cookie, but from many… and it’s not just cookies, it’s like the crumbs from an entire bakery, and the challenge is to determine the entire recipe book for that bakery.•For Solar System formation, the crumbs are the small leftovers of planetary formation, i.e., the comets and asteroidsAsteroidsSmall, primarily rocky bodiesMain Asteroid Belt-“The tiny terrestrials”-Small (sub-km to ~1000 km) composed mostly of rock with some metalJupiter Trojan Asteroids-Transition objects?-Very interesting group where little is knownMeteoritesBits of asteroids that contain snapshots of Solar System formation historyRadioactive dating of meteorites gives us an age of the Solar System at 4.568 (about 4.6) Billion Years OldCarbonaceous ChondriteIron MeteoriteOrdinary ChondritePallasite: Iron-Rock meteoriteMost Primitive (Unaltered)Least Primitive (Highly Altered)MetalRock &MetalIron-Rock Rock with metal grainsRock and OrganicsComets•Small (km to sub-km)•Made of Ice, Rock, and have organics–Quite complex organics… add water and energy and get all the amino acids•Formed far away from forming Sun•Comet stuff largely unaltered -> a peak at the ingredient listSmall leftovers of formationComet Hale-BoppComet 67P/C-GComet McNaughtESO, S. DeiriesThese dust grains are the building blocks of the Solar SystemNucleus of a cometComet DustDust likely left over from cometary activity Very small, and most likely amongst the most primitive and oldest materials in the Solar System.Contains grains formed in our Solar System formation process (See Nebular Theory), and a few grains are pre-solar grains (inherited from interstellar Space)Interplanetary Dust ParticlesA personal touchDr. Lindsay’s Ph. D. work used supercomputers to model the mid-infrared (wavelengths from 5 – 40 µm) spectral features of dust grains like this to determine: 1) What they are made out of; 2) What general shape they are; and 3) How big are they on average?From Messenger et al., in Meteoritic and the Early Solar System IIInterplanetary Dust ParticlesA personal touch•Spectrally determining composition of dust is a direct way to see our Solar System “Ingredient List”•Determining size gives us intel on how grains form•Spectrally determining shape (a major part of my research) gives us the temperature environment (and hence location) and formation method of grains. -> Topics still not well understoodFrom Messenger et al., in Meteoritic and the Early Solar System IIOur Solar SystemRemarkably flatRemarkably emptyExcept for Mercury, all planetary orbits nearly circular, and lie on the same plane (flat like a record/disk).•Drawn looking down onto the North Pole of Earth.•All orbits in same direction: counter-clockwise (ccw)Looking at Earth NPCompositional GradientTwo major types: Terrestrial and Gas GiantInner Planets are theTerrestrial PlanetsSmall Rocky Worldsw/ metallic coresNo organics.Outer Planets are theGas Giant, or Jovian, PlanetsHuge Gaseous WorldsWith icy-rocky moons & coresAlso organics!Outer Solar SystemKuiper Belt ObjectsTiny Icy-rocky Worldsw/ exotic icesAlso organics!Note: When I say rocky, I mean rock and metalsSolar System Density GradientDensity Gradient: As the
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