Astronomy Rough Notes Origin of the solar system/birth of stars and planets BRING Laptop Stool and masses Sunlamp and radiometer DISCLAIMER: These notes do NOT cover everything you need to know. You may need to look up some item or concept online or in a text. Test questions are not exact copies of the OBJECTIVES but if you know the OBJECTIVES thoroughly, you should do well on the exams. HANDOUTS: None OBJECTIVES: Give a brief overview of how scientists think stars and planets formed. List and describe evidence from our solar system that supports that overview. List and describe evidence from outside our solar system that supports that overview. What do the latest computer models suggest about the location of the Jovian planets? What is a nebula? What is a protostar? What did the rotating stool and masses illustrate? Name an excellent example of a star birth region. Why are the Terrestrial planets dense but the Jovian planets are not? Name and describe the two most common ways to find extraterrestrial planets (1. Doppler Shift a.k.a. radial velocity, 2. Transit). REFERENCES: Plenty out there, but a good start is at http://ircamera.as.arizona.edu/natsci102/natsci102/lectures/solarsysform.htm MATERIAL: Videos of how stars and planets form 1. Video of multiple stars forming in gas clouds is at http://www.youtube.com/watch?v=ybdwtwb8jtc&playnext=1&list=plfc84c8cba3c1b6d6&fea ture=results_video 2. Video of disk collapse and flattening and planets forming is at https://www.youtube.com/watch?v=pl3ynqk960y Executive summary A star is born inside a collapsing ball of gas and dust. As the material collapses inward, it flattens out into a disk that spins around together with the forming star like a spinning top. Jets of gas shoot perpendicularly away from the disk, above and below it. As the star ages, planets are thought to form out of the disk -- material clumps together, ultimately growing into mature planets. Eventually, most of the dust dissipates from http://www.spitzer.caltech.edu/news/1249-ssc2011-03-new-view-of-family- Life-in-the-North-America-Nebula http://www.universetoday.com/24663/protostar/
Conventional Picture from http://www.naoj.org/pressrelease/2011/02/17/supplement.html looks like this:
General characteristics of how stars/planets form (Solar Nebula Theory): Begin with large nebula (gas, dust cloud) Piece of nebula contracts (from shock waves and gravity) Shock wave can come from numerous sources such as galaxy collisions, a shockwave from a nearby Supernova explosion Gravitational energy is transferred into kinetic energy Flattens and rotates Rotates faster as it condenses (angular momentum)(conservation of angular momentum demo) Jets perpendicular to disk in a cocoon of gas and dust use IR light to see through dust Center Protostar Star Protostar is not yet a star, it is still gathering mass (material) from the parent molecular cloud As fusion ignites, light radiation blasts away dust cocoon Disk Smaller objects stick and collide to form larger objects Dense planets form near Sun, Less dense form further away (See Tutorial on Temperature and Solar System) Planets and debris jostle for position, sometimes colliding and sometimes ejecting each other Star turns on strong stellar winds from themselves and neighbors Some evidence in our solar system Sun at center Sun and planets not much else Flat/planar for most part Preferred direction of rotation and revolution Composition (Mostly H, He) Meteorites and comets Craters Shape/location of Oort Cloud/Kuiper Belt Mini systems like Saturn and Jupiter Terrestrial vs. Jovian planets Terrestrial planets only metal and silicates could condense and form solids close to the Sun. Slow formation ~30 million years Jovian metals, silicates, and ice condense at this distance from the Sun. Quick formation ~10 million years before the Sun blew away the remaining nebula. Location of Oort Cloud, Kuiper Belt and Asteroid Belt - Early solar system objects suffered violent collisions/encounters tossing smaller objects in all directions Water/Ice line http://www.almaobservatory.org/en/press-room/press-releases/989-almaobserves-first-protoplanetary-water-snow-line-thanks-to-stellar-outburst Evidence from outside the solar system Lots of gas and dust throughout Milky Way and other galaxies (many contain stars) o Milky Way band http://antwrp.gsfc.nasa.gov/apod/ap990224.html o Dark Nebulae Pipe Neb, Antares, Rho Oph. http://antwrp.gsfc.nasa.gov/apod/ap970621.html Molecular Cloud Barnard 68 http://antwrp.gsfc.nasa.gov/apod/ap990511.html Horsehead http://antwrp.gsfc.nasa.gov/apod/ap990519.html o Emission Neb North America Neb. http://antwrp.gsfc.nasa.gov/apod/ap960606.html
o Reflection Neb. Witch Head http://antwrp.gsfc.nasa.gov/apod/ap990829.html Pleiades http://antwrp.gsfc.nasa.gov/apod/ap981025.html o Hot young stars in gas cloud in M33 http://antwrp.gsfc.nasa.gov/apod/ap960816.html Star birth regions (gas clouds) o Rosette Nebula http://antwrp.gsfc.nasa.gov/apod/ap000111.html o Trifid Nebula http://antwrp.gsfc.nasa.gov/apod/ap980331.html o Orion Nebula (know this one) Matt Russell s photo of Orion Nebula http://www.telescopes.cc/m42.htm Step into Orion Nebula at http://hubble.stsci.edu/newscenter/newsdesk/archive/releases/2002/05/video/a Fly through at http://hubble.stsci.edu/newscenter/newsdesk/archive/releases/2001/13/video/a Cocoons of star birth in Orion Nebula o Proplyds in Orion http://antwrp.gsfc.nasa.gov/apod/ap961017.html o Planetary Systems Now Forming in Orion http://antwrp.gsfc.nasa.gov/apod/ap961207.html Preferred rotation/revolution of solar systems o Demo as gas cloud collapses, rotation/revolution speeds up o Flattening of disk o Rings in Beta Pic disk http://antwrp.gsfc.nasa.gov/apod/image/0002/betapic2_hst_big.jpg Spitzer views of discs and collisions http://www.spitzer.caltech.edu/news/172-ssc2004-17-astronomers-discover-planet-building-is-big- Mess- Protostar and strong stellar winds Hubble image of star forming region http://hubblesite.org/newscenter/archive/2003/13/ Hot stellar winds (M8 Hourglass neb. In Lagoon Neb.) http://hubblesite.org/newscenter/newsdesk/archive/releases/1996/38/ Pillars in Eagle Nebula slides or search on it on the web. http://hubblesite.org/newscenter/newsdesk/archive/releases/1995/44/image/a or http://antwrp.gsfc.nasa.gov/apod/ap000924.html Demo - radiometer Star turns on o McNeill s Nebula series http://www.rc-astro.com/nebulae/mcneil_anim.htm Orbits of extrasolar planets ALMA o http://www.almaobservatory.org/en/press-room/press-releases/937-almas-best-image-yetof-a-protoplanetary-disk First visible light image of exoplanet http://antwrp.gsfc.nasa.gov/apod/ap081114.html NGC 3603: From Beginning To End http://antwrp.gsfc.nasa.gov/apod/ap990604.html
Latest computer models Outer planets were in different locations then they are today. For example, see the simulations in http://ircamera.as.arizona.edu/natsci102/natsci102/lectures/solarsysform.htm Wandering large planets encounter many smaller objects in the disk engulfing some, ejecting some from the solar system, and flinging many to the edges of the solar system (Oort Cloud, Kuiper Belt, Asteroid Belt) Other models suggest some if not many comets were captured from other stars (http://science.nasa.gov/science-news/science-at-nasa/2010/23nov_aliencomets ) How to Find Planets https://exoplanets.nasa.gov/interactable/11/ Planets tug on their parent stars causing a slight side-to-side or forward-backward wobble of the star Four methods 1. Doppler Shift (a.k.a. radial velocity method) Measures shifts in the spectral lines coming from the wobbling star. 2. Transit Measure the slight dip in the light coming from the star as a planet passes in front of the star. 3. Direct imaging very difficult planets tiny and distant light from star swamps light from planet. a. Look at rings of debris around some stars (rings have knots piled up by a planet 4. Microlensing Light is bent around a planet passing front of a distant star See BBC and Sir Patrick Moore at http://www.bbc.co.uk/programmes/p009gxf2. How Many Other Planets Have We Found http://www.nasa.gov/home/hqnews/2013/jan/hq_13-008_kepler_new_planets.html As of March 2017: 3,461 Confirmed 4,696 Candidates 2,584 Star Systems 352 Terrestrial Planets HOMEWORK Make a flashcard for each objective. Work the tutorial on Temperature and our Solar System View the BBC clip at http://www.bbc.co.uk/programmes/p009gxf2