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Stars and Galaxies Created by the Lunar and Planetary Institute For Educational Use Only LPI is not responsible for the ways in which this powerpoint may be used or altered. Space Science for Middle School at HCDE February 20, 2009 Image at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2009/07/image/g/results/50/ Welcome! Please complete the pre-assessment It’s for us—it’s not about you Please let us know how much YOU know, not how much your friends sitting next to you know What are we going to cover? Our Place in the Universe The Electromagnetic Spectrum Classifying Stars Classifying Galaxies History of the Universe First up… Our Place in the Universe What is our Universe made of? How big are things? How far away? How do we know? What is our Universe made of? What was in your drawing? Stars and planets Gas and dust Organized into star clusters Organized into nebulae Organized into galaxies Other things: Black holes Dark matter Dark energy Image from http://galileo.rice.edu/lib/student_work/astronomy95/orionpleiades.html Activity!! Use the Venn diagrams to place the stickers—where does everything go? After you’re finished, let’s discuss… Examining the Components Stars Gas and dust (Nebulae) Star clusters Galaxies Different types of stars Image from http://hubblesite.org/newscenter/archive/releases/star%20cluster/globular/2003/21/image/a/results/50/ Types of Stars Big Small Red Blue Yellow In groups Alone More later What is a “star cluster”? stars formed together at same time stars may be gravitationally bound together two types: open (galactic) and globular Image at http://hubblesite.org/newscenter/archive/releases/star%20cluster/globular/2007/18/image/a/format/web/results/50/ Open Clusters dozens to thousands of stars young stars! only a few million years old may still be surrounded by nebula from which they formed located in the spiral arms of a galaxy example: Pleiades Image at http://hubblesite.org/newscenter/archive/releases/star%20cluster/open/2004/20/image/a/results/50/ More open star clusters Image from http://hubblesite.org/newscenter/archive/releases/star%20cluster/open/2006/17/image/a/results/50/ Globular Clusters millions to hundreds of millions of stars old! 6 to 13 billion years mostly red giants and dwarfs stars are clumped closely together, especially near the center of the cluster (densely) surround our disk as a halo Image at http://hubblesite.org/newscenter/archive/releases/star%20cluster/globular/1999/26/image/a/results/50/ What is a “nebula”? A cloud in space Made of gas and dust Can have stars inside Most of the ones we see are inside our Milky Way Galaxy Different types Orion image at http://hubblesite.org/newscenter/archive/releases/2006/01/image/a/results/50/ Large, massive, bright nebulae Emission Nebula •The hot gas is emitting light Orion image at http://hubblesite.org/newscenter/archive/releases/2006/01/image/a/results/50/ Colder, darker nebulae Dark dust blocking the hot gas behind it NOAO/AURA/NSF Image from http://hubblesite.org/newscenter/archive/releases/nebula/dark/2001/12/image/c/results/50/ Leftovers from an Explosion Supernova remnant (smaller, less gas) Image at http://hubblesite.org/newscenter/archive/releases/nebula/supernova-remnant/2005/37/results/50/ What is a “galaxy”? A large group of stars outside of our own Milky Way Made of billions to trillions of stars Also may have gas and dust Spiral, or elliptical, or irregular shaped Image at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2007/41/results/50/ Spiral galaxy--Andromeda NOAO/AURA/NSF Images at http://www.noao.edu/image_gallery/html/im0606.html and http://www.noao.edu/image_gallery/html/im0685.html Elliptical Galaxies Images at http://hubblesite.org/newscenter/archive/releases/galaxy/elliptical/2007/08/image/a/format/large_web/results/50/ and http://hubblesite.org/newscenter/archive/releases/galaxy/elliptical/1995/07/results/50/ Irregular Galaxies NASA and NOAO/AURA/NSF Images at http://hubblesite.org/newscenter/archive/releases/galaxy/irregular/2005/09/results/50/ , http://www.noao.edu/image_gallery/html/im0560.html , and http://www.noao.edu/image_gallery/html/im0993.html Our Galaxy: the Milky Way has about 200 billion stars, and lots of gas and dust is a barred-spiral (we think) about 100,000 light-years wide our Sun is halfway to the edge, revolving at half a million miles per hour around the center of the Galaxy takes our Solar System about 200 million years to revolve once around our galaxy The Milky Way Image at http://news.nationalgeographic.com/news/bigphotos/1945371.html Mapping the Milky Way How do we know what our Galaxy looks like? We can see stars star clusters nebulae Galaxies Let’s try to Map our Galaxy Measuring Distances Parallax (let’s model it) As Earth orbits the Sun, we see nearby stars move relative to more distant stars How many degrees did the plate move, relative to the background? Can you calculate the distance to the plate? Sine of the parallax (angle) x Earth’s distance to the Sun = Distance to the star The angles involved for strellar observations are very small and difficult to measure. Proxima Centauri, has a parallax of 0.77 arcsec. This angle is approximately the angle subtended by an object about 2 centimeters in diameter located about 5.3 kilometers away. Measuring Distances What is a Light Year? A light year is the distance light travels in a year. Light moves at a velocity of about 300,000 kilometers (km) each second; how far would it move in a year? About 10 trillion km (or about 6 trillion miles). Why do we use light years? Show me how far 5 centimeters is. Now show me 50 centimeters. Now tell me (without thinking about it, or calculating it in meters) how far 500 centemeters is. 2000? 20,000? We need numbers that make sense to us in relationship to objects; we scale up and use meters and kilometers for large numbers. Time for a Break! Next Up Our Place in the Universe The Electromagnetic Spectrum Classifying Stars Classifying Galaxies History of the Universe Let’s check your knowledge Please draw an electromagnetic spectrum on a sheet of paper, and label the parts. You can work in groups. Radiation There are lots of types of light (radiation), including visible and invisible Electromagnetic spectrum http://coolcosmos.ipac.caltech.edu/cosmic_classroom/ir_tutorial/what_is_ir.html . Let’s Observe A Spectrum What will the spectrum look like with a red filter in front of your eyes? A blue filter? Hypothesize and test your hypothesis. Now let’s examine the invisible parts— using our cell phones and a solar cell. There are different types of spectra Continuous Emission or Bright Line (from ionized gas, like a nebula or a neon sign) Absorption or dark line (from stars) Illustration at http://imagine.gsfc.nasa.gov/docs/science/how_l1/spectra.html Radiation All stars emit radiation Radio, infrared, visible, ultraviolet, x-ray and even some gamma rays Most sunlight is yellow-green visible light or close to it The Sun at X-ray wavelengths Image at http://imagine.gsfc.nasa.gov/docs/sc ience/know_l1/sun.html Image and info at http://imagine.gsfc.nasa.gov/docs/teachers/gammaraybursts/imagine/page18.html Using a Star’s Spectrum We can use a star’s spectrum to classify it. NOAO/AURA/NSF image at http://antwrp.gsfc.nasa.gov/apod/ap010530.html Stellar Evolution Time to Create a Stellar Graph Everyone will receive several “stars” Place them on the large paper, according to their color and their brightness This is a version of the Hertzsprung-Russell diagram. Hertzsprung-Russell Diagram Images from http://www.nasa.gov/centers/goddard/news/topstory/2007/spectrum_plants.html and http://sunearthday.gsfc.nasa.gov/2009/TTT/65_surfacetemp.php Young stars form in nebulae from Small Magellanic Cloud Image at http://hubblesite.org/newscenter/archive/releases/2007/04/image/a/results/50/ Star-forming region in the Large Magellanic Cloud: http://hubblesite.org/newscenter/archive/releases/2008/31/image/a/results/50/ Orion image at http://hubblesite.org/newscenter/archive/releases/2006/01/image/a/results/50/ Interstellar “eggs” Movie at http://www.stsci.edu/EPA/PR/95/44/M16.mpg Our Sun is a Regular/ Small Star On the “Main Sequence” Image at http://www.gsfc.nasa.gov/topstory/20011210insidesun.html In a few Billion years… Red Giant Image at http://hubblesite.org/newscenter/archive/releases/1997/26/image/a/ Our Sun’s Habitable Zone Billions of years ago, things may have been different The Sun was cooler (by up to 30%!) Earth’s atmosphere was different (thicker, carbon dioxide) Conditions will be different in the future By many accounts, increases in the Sun’s temperature will make Earth uninhabitable in 1 billion years or less These changes will also affect other planets… Mars? Animation at http://www.nasa. gov/97994main _BHabitableZon e.MPG By 5 billion years… White Dwarf Small, but very hot Image at http://hubblesite.org/newscenter/archive/releases/nebula/planetary/1998/39/results/50/ Image at http://hubblesite.org/newscenter/archive/releases/nebula/planetary/2000/28/image/a/format/web_print/results/50/ Image at http://hubblesite.org/newscenter/archive/releases/nebula/planetary/2004/27/image/a/format/large_web/results/50/ Massive Stars are different On the “Main Sequence” but not for long Image from http://hubblesite.org/newscenter/archive/releases/nebula/emission/1997/33/results/50/ Betelgeuse—Red Supergiant Image from http://hubblesite.org/newscenter/archive/releases/star/massive%20star/1996/04/image/a/results/50/ Supernova—Massive Star Explodes Images at http://hubblesite.org/newscenter/archive/releases/star/supernova/2004/09/results/50/ http://hubblesite.org/newscenter/archive/releases/nebula/supernova-remnant/2005/37/results/50/ http://chandra.harvard.edu/photo/2009/casa/ Neutron Star or Pulsar Image at http://hubblesite.org/newscenter/archive/releases/nebula/supernova-remnant/2002/24/results/50/ Black Hole Image at http://hubblesite.org/newscenter/archive/releases/2002/30/image/a/results/50/ Classifying Galaxies Galaxies come in different sizes (dwarf, large, giant) come in different shapes and classifications Spirals Ellipticals Lenticulars Irregulars are fairly close together, relative to their sizes Spiral Galaxies have flat disk, spiral arms, central bulge, and a surrounding halo some have a “barred” bulge are fairly large (no dwarf spirals) have lots of gas and dust and younger stars in their arms, but older stars and little gas or dust in their halos and central bulges Galaxies Image at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2005/01/results/50/ Spiral galaxy--Andromeda NOAO/AURA/NSF Images at http://www.noao.edu/image_gallery/html/im0606.html and http://www.noao.edu/image_gallery/html/im0685.html Spiral Galaxy on Edge Image at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2006/24/image/a/results/50/ Image at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2007/41/results/50/ Elliptical galaxies range from spherical to football shaped range from very small to giant have very little gas or dust mostly old stars similar to the central bulge of a spiral galaxy Elliptical Galaxies Images at http://hubblesite.org/newscenter/archive/releases/galaxy/elliptical/2007/08/image/a/format/large_web/results/50/ and http://hubblesite.org/newscenter/archive/releases/galaxy/elliptical/1995/07/results/50/ Lenticular have a disk but no arms have little or no excess gas and dust Image at http://hubblesite.org/newscenter/archive/releases/galaxy/elliptical/2002/07/results/50/ Irregular Galaxies any galaxy that isn’t a Spiral, Elliptical, or Lenticular usually have lots of gas and dust and young stars may have a distorted shape from interaction with another galaxy Irregular Galaxies NASA and NOAO/AURA/NSF Images at http://hubblesite.org/newscenter/archive/releases/galaxy/irregular/2005/09/results/50/ , http://www.noao.edu/image_gallery/html/im0560.html , and http://www.noao.edu/image_gallery/html/im0993.html Collisions! We now think that galaxies in groups and clusters often collide The Milky Way is moving at 300,000 mph toward the Andromeda Galaxy They may collide in about 5 billion years Stars don’t usually collide New orbits, gas piles up to form new stars Interacting Image from http://hubblesite.org/newscenter/archive/releases/galaxy/interacting/2000/34/results/50/ the Antennae or Mice Information at http://hubblesite.org/newscenter/archive/releases/galaxy/interacting/1997/34/results/50/ The occasional results of two galaxies colliding: ringed galaxies Images from http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2002/21/image/a/results/50/ and http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/1999/16/image/a/results/50/ Various galaxies (can you identify types?) Image at http://hubblesite.org/newscenter/archive/releases/galaxy/cluster/1999/31/results/50/ Supermassive black holes almost every medium to large galaxy we’ve check has a supermassive black hole at the center the larger the galaxy, the more massive the black hole we don’t know which comes first, the galaxy or the black hole we think that these black holes are responsible for some of the galaxies with jets and lobes which give off radio waves, x-rays, etc. Active galaxy Image at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2000/37/results/50/ at the center of a large galaxy Image at http://hubblesite.org/newscenter/archive/releases/exotic/black-hole/1998/22/results/20/ and http://hubblesite.org/newscenter/archive/releases/exotic/black%20hole/2000/21/image/a/format/web_print/results/20/ Galaxy Clusters the Local Group includes the Milky Way, the Andromeda, and over 30 other smaller galaxies the Virgo Cluster hundreds to thousands of galaxies, 60 million lightyears away giant elliptical at center, formed by galactic cannibalism the Local Group is “falling” toward the Virgo Cluster at 60 to 250 miles per second! Coma Cluster Image at http://hubblesite.org/newscenter/archive/releases/galaxy/cluster/2008/24/image/a/results/20/ Superclusters! clusters are bound together in larger structures, called superclusters these superclusters have been mapped, and are grouped into long strings 300 million to a billion light-years long 100 to 300 million light-years wide and only 10 to 30 million light-years thick in between these strings are huge voids of galaxies, although some astronomers may have detected hot gas Evolution of Galaxies Image at http://www.galex.caltech.edu/media/glx2007-05f_img01.html Origin of the Universe Big Bang Dominant scientific theory about the origin of the universe Occurred ~13.7 billion years ago What is the Big Bang? How do we know? What is the Big Bang? Infinitely dense point not governed by our physical laws or time All matter and energy contained in one point Image from http://www.newscientist.com/articleimages/dn11799/0-didantimatter-factory-spark-brightest-supernova.html Building a Universe Instantaneous filling of space with all matter History of the Universe •10-43 seconds - gravity separates from other forces •10-35 to 10-32 seconds - fundamental particles - quarks and electrons •10-6 seconds - quarks combine into protons and neutrons •1 second - electromagnetic and weak nuclear forces separate •3 minutes - protons and neutrons combine into atomic nuclei •105 years - electrons join nuclei to make atoms; light is emitted •105-109 years - matter collapses into clouds, making galaxies and stars Orion Nebula - http://stardate.utexas.edu/resources/ssguide/planet_form.html History of the Universe Image from http://dsc.discovery.com/space/top-10/strange-universe/space-10-weirdest-things-universe-10.html Later History Image at http://www.galex.caltech.edu/media/glx2004-01r_img02.html Big Bang Theory In 1915, Albert Einstein concluded that the universe could not be static based on his recently-discovered theory of relativity and added a "cosmological constant" to the theory of relativity because astronomers assured him that the universe was static Aleksandr Friedmann and Abbe George LeMaitre are credited with developing the basics of the Big Bang model between 1922 and 1927; their calculations suggested that universe is expanding, not static. Years later, Einstein called his cosmological constant the biggest mistake of his career Image at http://map.gsfc.nasa.gov/universe/bb_theory.html Expanding Universe In 1929, Edwin Hubble showed that most galaxies are red-shifted (moving away from us), and that a galaxy’s velocity is proportional to its distance (galaxies that are twice as far from us move twice as fast) Image from http://imagine.gsfc.nasa.gov/docs/science/mysteries_l1/origin_destiny.html Hubble’s Evidence Doppler shifting - wavelength emitted by something moving away from us is shifted to a lower frequency Sound of a fire truck siren - pitch of the siren is higher as the fire truck moves towards you, and lower as it moves away from you Visible wavelengths emitted by objects moving away from us are shifted towards the red part of the visible spectrum The faster they move away from us, the more they are redshifted. Thus, redshift is a reasonable way to measure the speed of an object. When we observe the redshift of galaxies, almost every galaxy appears to be moving away from us – the Universe is expanding. Predictions for the Big Bang Model The expansion of the Universe Edwin Hubble's 1929 observation that galaxies were generally receding from us provided the first clue that the Big Bang theory might be right. The abundance of the light elements H, He, Li The Big Bang theory predicts that these light elements should have been fused from protons and neutrons in the first few minutes after the Big Bang. The cosmic microwave background (CMB) radiation The early universe should have been very hot. The cosmic microwave background radiation is the remnant heat leftover from the Big Bang. Evidence for Big Bang Red shift - as light from distant galaxies approach earth there is an increase of space between earth and the galaxy, which leads to wavelengths being stretched In 1964, Arno Penzias and Robert Wilson, discovered a noise of extraterrestrial origin that came from all directions at once radiation left over from the Big Bang In June 1995, scientists detected helium in the far reaches of the universe - consistent with an important aspect of the Big Bang theory that a mixture of hydrogen (75%) and helium (25%) was created at the beginning of the universe When Did the Universe Form? Cosmic background radiation temperature on celestial sphere ~13.7 billion years ago How do we know? Spreading (Red Shift) know distances, rates of retreat, relative positions Pervasive background radiation of 2.7°C above absolute zero - afterglow of the Big Bang http://timeline.aps.org/APS/resources/85_06a.jpg Feedback, Questions Reach us online at http://www.lpi.usra.edu/education/ For more information, contact Christine Shupla Lunar and Planetary Institute 3600 Bay Area Blvd Houston, TX 77058 (281) 486-2135 [email protected]
