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Lec. 21: The Milky Way21 -1 Lec. 21: The Milky Way21 -1

Lec. 21: The Milky Way21 -1 - PDF document

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Lec. 21: The Milky Way21 -1 - PPT Presentation

Lec21 The Milky Way The Milky Way GalaxyLecture 21APOD Lec21 The Milky WayAtomic molecular and ionized gas Lec 21 The Milky Way21 2 Lec21 The Milky Way ID: 122430

Lec21: The Milky Way The Milky

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Lec. 21: The Milky Way21 -1 Lec21: The Milky Way The Milky Way GalaxyLecture 21APOD Lec21: The Milky WayAtomic, molecular, and ionized gas Lec. 21: The Milky Way21 -2 Lec21: The Milky Way“River of Milk”from horizon to horizon”(capitalized) is used to Milky Way Schematic “Face-on”View “Edge-on”View Lec. 21: The Milky Way21 -3 Lec21: The Milky Waycentury, Kapteyn Lec21: The Milky Way 020,000 ly-20,000 ly SunDoing this it appears that we are near the center of an elliptical distribution of stars! Lec. 21: The Milky Way21 -4 Lec21: The Milky Waycorrect. The Milky Way in Sagittarius Patchiness due to dust extinction Lec. 21: The Milky Way21 -5 Lec21: The Milky Way Lec21: The Milky Way Thin Disk Globular clustersin the halo. Lec. 21: The Milky Way21 -6 Lec21: The Milky WayMilky Way. Whole galactic plane in visible Again, patchiness due to dust extinction Lec. 21: The Milky Way21 -7 Whole galactic plane in Near-Infrared (2MASS)Near-IR shows stars in the galaxy. Less extinction than visible Galactic Infrared View Lec. 21: The Milky Way21 -8 Whole galactic plane in Far-Infrared (IRAS) Galactic plane and star formation regions show up in Far-IR Whole galactic plane in Radio Continuum Radio shows regions of star formation and supernova remnants Lec. 21: The Milky Way21 -9 The Milky Way across the spectrum Lec21: The Milky WayThe Milky Way is ~12-15 kpcin radius The Sun is ~8.5 kpcfrom the center. Lec. 21: The Milky Way21 -10 Lec21: The Milky Way Schematic of the Milky Way Nuclear Bulge“Edge-on”View Lec21: The Milky WayA very thin “pancake”of stars (Pop Thickness:100 pc (O-stars) to Lec. 21: The Milky Way21 -11 Lec21: The Milky Way Lec21: The Milky WaySpiral Arm DetailsWave patterns occur in These “spiral density waves”trigger star formation. Ionization nebulae arise where newly forming blue stars are ionizing gas cloudsYoung blue stars are found on outer edge of spiral arm Lec. 21: The Milky Way21 -12 Lec21: The Milky Way -spherical distribution of stars and Bulge -dense swarm of stars centered on Bulge radius ~1.5 kp Lec21: The Milky Way Stellar Orbits Lec. 21: The Milky Way21 -13 Lec21: The Milky Way -mainly HI atoms which can -mainly Hmolecules which are traced by CO molecules, since Lec21: The Milky WayStar-forming cloudsMolecular hydrogenMolecular Regions of star formationMolecular hydrogenMolecular cloudsIntermediate stage of star-gas-star cyclehydrogenhydrogenWarm atomic Pockets of gas heated by supernova shock waveshydrogen Description Approx.Density (atoms/cm Approx.Temperature PrimaryConstituent State of Gas Lec. 21: The Milky Way21 -14 Lec21: The Milky Way“heavy”elements into the ISM.SNR “stir up”the ISM. X-ray view of Tycho’ssupernova remnant (7500 lyraway, 20 lyracross Butterfly Nebula Lec. 21: The Milky Way21 -15 Lec21: The Milky WayHeight ~ 250 pc in center, 1 kpcat 20 kpc Lec21: The Milky Way 250 pc Sun 1 kpcwarp inthe disk 20 kpc gas Lec. 21: The Milky Way21 -16 Lec21: The Milky Wayfrom 4-8 kpcand concentration on GCGiant MolcularClouds (GMCs):Size ~ 10 -50 pc, Mass ~ 10-10sun Lec21: The Milky Way SunGalactic “Ring”of GMCsat 4-8 kpc sun sun