Week 11 Module 01 - Exploring the Universe (Ast1001) PDF

11/12/24 Copyright © 2024 C.E. Woodward. All rights reserved. For U. Minnesota AST1001 Fall 2024 student use exclusively (enrolled individuals). Electronic dissemination, web...

11/12/24 Copyright © 2024 C.E. Woodward. All rights reserved. For U. Minnesota AST1001 Fall 2024 student use exclusively (enrolled individuals). Electronic dissemination, web postings, social media posting, pay-wall site posting, class-notes website postings, etc. is strictly prohibited. Motivation Watch epic Sun highlights for SOHO observatory's 25th anniversary Fares, coronal mass ejections, sunspots and more in these highlights from the Solar and H eliospheric Observatory (SOH O) from the last 25 years. The observatory launched on Dec. 2, 1995. Ast1001 Exploring the Universe 03:22 Week 11 Module 01 https://w w w.youtube.com /w atch?v=ooiN oQ M J3fg& t=5s W K 11 M od01 ASTRONOMY – C.E. WOODWARD 1 W K 11 M od01 ASTRONOMY – C.E. WOODWARD 2 1 2 Today’s Objectives and Discussion Topics “Ask an Astronomer” – Question and Answer Forum q The Sun as a Star q Energy generation in the Sun’s interior q Sun as a pulsating “bell.” q Stellar Hydrostatic Equilibrium ns? uestio re Your Q a What 5 Mins * W K 11 M od01 ASTRONOMY – C.E. WOODWARD 3 ASTRONOMY – C.E. WOODWARD 4 3 4 1  11/12/24 Copyright © 2024 C.E. Woodward. All rights reserved. For U. Minnesota AST1001 Fall 2024 student use exclusively (enrolled individuals). Electronic dissemination, web postings, social media posting, pay-wall site posting, class-notes website postings, etc. is strictly prohibited. Major Topic – Part 3 The Sun — The Nearest Star 12 nd 11 a C hs Basic Properties And Internal Structure er e d in ls cov Nuclear Reactions a te r ia gM d in Solar Luminosity R ea Structure Of The Solar Atmosphere How do Stars Contribute to the Chemical Enrichment Cycle? Investigating Metallicity Variations, Stellar Populations, & Stellar Structure Solar Wind Sunspots And Solar Activity The image at the far left shows a very active X-ray Sun (1991). The image on the far right was taken in 1995 and shows our Sun with few X-rays coming from it. The images shown in this picture are 4 months apart. W K 11 M od01 ASTRONOMY – C.E. WOODWARD 5 W K 11 M od01 ASTRONOMY – C.E. WOODWARD 6 5 6 General Structure Of The Sun General Structure Of The Sun Basic Properties Basic Properties Sun is essentially a giant ball of hot gas, technically a plasma − a gas in which the atoms are ionized because of the high temperatures W K 11 M od01 ASTRONOMY – C.E. WOODWARD 7 W K 11 M od01 ASTRONOMY – C.E. WOODWARD 8 7 8 2  11/12/24 Copyright © 2024 C.E. Woodward. All rights reserved. For U. Minnesota AST1001 Fall 2024 student use exclusively (enrolled individuals). Electronic dissemination, web postings, social media posting, pay-wall site posting, class-notes website postings, etc. is strictly prohibited. General Structure Of The Sun General Structure Of The Sun Composition Photosphere “Surface” That We See At Optical Wavelengths Solar composition know from identifying the absorption lines in the Sun’s spectrum. Temperature ≈ 5800 K Absorption Lines Formed In This Region Fraunhofer Lines Prominent Lines Lettered Used to Estimate Elemental Abundances These lines are formed in the photosphere. Photosphere (Greek for “light”) − the visible “surface” of the Sun K H W K 11 M od01 ASTRONOMY – C.E. WOODWARD 9 W K 11 M od01 ASTRONOMY – C.E. WOODWARD 10 9 10 Energy Generation In The Sun Energy Generation In The Sun Nuclear Fusion Nuclear Fusion Stars Generate Energy Primarily From Fusion Processes Symbol for solar radius Core 7 T = 1.5 x 10 K; Depth = 0 – 0.25 R This is where the Sun’s energy is generated. PROTON – PROTON CHAIN ( pp-chain ) Describes How Stars On The Main-sequence Generate Energy Thru Nuclear Fusion H eavy to Lighter Element Lighter to H eavier Element Basically : 4H Þ 1 He Fusion only Possible in the Dense Core Regions of Stars. Here RELEASING ENERGY The Temperature is Very High, Greater than 1 million ºK Densities are Extreme Atoms Like Hydrogen are Ionized Hans Bethe The Sun (and all stars) shine by converting mass into energy through nuclear fusion. W K 11 M od01 ASTRONOMY – C.E. WOODWARD 11 W K 11 M od01 ASTRONOMY – C.E. WOODWARD 12 11 12 3  11/12/24 Copyright © 2024 C.E. Woodward. All rights reserved. For U. Minnesota AST1001 Fall 2024 student use exclusively (enrolled individuals). Electronic dissemination, web postings, social media posting, pay-wall site posting, class-notes website postings, etc. is strictly prohibited. Energy Generation In The Sun Energy Generation In The Sun Nuclear Fusion Nuclear Fusion Normal Regions Coulombic Repulsion 𝑞𝑞! 𝑞𝑞" Fes = 𝑟𝑟 " q is particle charge In QCD – represents interactions between quarks and gluons (elementary particles) In Stellar Cores D euterium Produced H elium -3 Produced H elium -4 Produced Gamma Rays H eat the Surrounding Gas Strong Nuclear Force 4 Protons - Difference Mass in Final Product An Alpha Particle (or H e Nucleus) W K 11 M od01 ASTRONOMY – C.E. WOODWARD 13 W K 11 M od01 ASTRONOMY – C.E. WOODWARD 14 13 14 Energy Generation In The Sun Energy Generation In The Sun Nuclear Fusion Photon Random Walk In The Core Of The Sun — Inner Most 10% Of The Sun’s Diameter is Where Fusion Reactions Occur Free-flight at the photosphere Randomly bouncing photons carry energy through the deepest 4 H Þ 1He + Energy + 2 Neutrinos + 2 Positrons layers of the Sun, and convection carries energy through the upper layers to the surface. Very Tiny M ass Inner radiative zone 6.693 × 10 -24 gm - 24 6.645 × 10 gm 2 E = mc Difference in mass Þ Energy Gamma-ray Photon Absorbed And Emitted Many Times Dmass = 0.048 × 10 -24 gm (Slow Radiative Transfer Process ≈ 100,000 Yrs to Complete) “Down Conversion” From Gamma - Ray Photons To Many Optical Photons Example — 3 milligrams of Material Þ 75 years of human life (2000 cals/day) Energy Loss H eats Surrounding Gas W K 11 M od01 ASTRONOMY – C.E. WOODWARD 15 W K 11 M od01 ASTRONOMY – C.E. WOODWARD 16 15 16 4  11/12/24 Copyright © 2024 C.E. Woodward. All rights reserved. For U. Minnesota AST1001 Fall 2024 student use exclusively (enrolled individuals). Electronic dissemination, web postings, social media posting, pay-wall site posting, class-notes website postings, etc. is strictly prohibited. Energy Generation In The Sun Energy Generation In The Sun Photon Radom Walk https://www.youtube.com/watch?v=cGY8L8cb-g0 Convection Zone Sun’s photosphere churns with rising hot gas and falling cool gas a result on underlying convection. 02:14 W K 11 M od01 ASTRONOMY – C.E. WOODWARD 17 W K 11 M od01 ASTRONOMY – C.E. WOODWARD 18 17 18 Energy Generation In The Sun Energy Generation In The Sun Convection Zone Super Computer Simulation – Solar Convection Zone 06:48 00:18 ( M. STEFFEN / STERNPHYSIK ) W K 11 M od01 ASTRONOMY – C.E. WOODWARD 19 W K 11 M od01 ASTRONOMY – C.E. WOODWARD 20 19 20 5  11/12/24 Copyright © 2024 C.E. Woodward. All rights reserved. For U. Minnesota AST1001 Fall 2024 student use exclusively (enrolled individuals). Electronic dissemination, web postings, social media posting, pay-wall site posting, class-notes website postings, etc. is strictly prohibited. Energy Generation In The Sun Energy Generation In The Sun Convection Zone Solar Pulsation – 5-minute Oscillations (Primary Mode) H elioseismology Fraunhofer Lines: Use of characteristic observed modes of vibration High Dispersion Spectra support out mathematical models of the Sun. Lines Exhibit Wavelength Oscillations About “Rest” Wavelengths Doppler Shift ─ Relative Motion Solar sounds were generated from SOHO/MDI data and Sun’s Vertical Motions of ≈ 0.4 km s-1 processed by A. Kosovichev. You are hearing three pulsation modes (l=0,n=21, l=1,n=20, l=2,n=20, nu=2.95-3.05 mHz) at a 44.1 kHz sampling rate. For m ore audio files see: Evidence Of Stellar Pulsation http://solar-center.stanford.edu/singing/SO U N D S/ l rest (Image cCredit: MDI/SOHO /NASA/E.J. Rhodes et al. ) 00:19 W K 11 M od01 ASTRONOMY – C.E. WOODWARD 21 W K 11 M od01 ASTRONOMY – C.E. WOODWARD 22 21 22 “Ask an Astronomer” – Question and Answer Forum Energy Generation In The Sun Hydrostatic Equilibrium: Stability of the Sun P mg Force P= Area GM 2 Fgas = P × A = (nkT ) × A = (nkT ) × R 2 @ Fgrav = ns? R2 uestio re Your Q Pressure Proportional To Temperature a What “Weight” Proportional To Mass 5 Mins * Both Temperature And Pressure Increase Toward Solar Core ASTRONOMY – C.E. WOODWARD 23 W K 11 M od01 ASTRONOMY – C.E. WOODWARD 24 23 24 6  11/12/24 Copyright © 2024 C.E. Woodward. All rights reserved. For U. Minnesota AST1001 Fall 2024 student use exclusively (enrolled individuals). Electronic dissemination, web postings, social media posting, pay-wall site posting, class-notes website postings, etc. is strictly prohibited. Energy Generation In The Sun Hydrostatic Equilibrium: Gravitational Equilibrium Energy Balance Ast1001 Exploring the Universe Week 11 Module 02 Two types of balance keep the Sun stable 1. Pressure balance gravity 2. Fusion energy balances energy radiated into space W K 11 M od01 ASTRONOMY – C.E. WOODWARD 25 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 26 25 26 Today’s Objectives and Discussion Topics Energy Generation In The Sun Solar Luminosity Why does the Sun “shine”? q The Neutrinos About 4.5 billion years ago gravitational contraction made the Sun hot enough to sustain nuclear fusion in its core. Ever since, energy liberated by fusion has maintained hydrostatic equilibrium and energy balance with the Sun, keeping it shining steadily. q Stellar Photosphere Features The Sun’s luminosity is stable over the short-term. q Sunspots However, as more Hydrogen fuses into Helium: four H nuclei convert into one He nucleus q Aurorae the number of particles in Sun’s core decreases with time the Sun’s core will contract, causing it to heat up the fusion rate will increase to balance higher gravity a new equilibrium is reached for stability at a higher energy output the Sun’s luminosity slowly increases with time over the long-term W K 11 M od02 ASTRONOMY – C.E. WOODWARD 27 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 28 27 28 7  11/12/24 Copyright © 2024 C.E. Woodward. All rights reserved. For U. Minnesota AST1001 Fall 2024 student use exclusively (enrolled individuals). Electronic dissemination, web postings, social media posting, pay-wall site posting, class-notes website postings, etc. is strictly prohibited. Energy Generation In The Sun Stellar Lifetime — Sun Solar Luminosity Main Sequence Lifetime How Much Energy Is Radiated Per Second by the Sun Compare: Total Energy Production Versus Luminosity Estimate: H – Fusion (Main-sequence) Lifetime Via Calculating How Much Mass Can Be Converted ù Into Energy Energy Produced Timescale ≅ Energy Lost 1 AU E∗ 1.3×10 51 ergs “Solar Constant” Timescale ≅ ≅ ≅ 3.2 ×1017 s @ 10 6 ergs s -1 cm -2 L∗ 3.9 ×10 33 ergs s −1 ­ Inverse Square Law Of Radiation ­ Conservation Of Energy Or Roughly ⇒ 10 Billion years L* = (solar constant ) × 4p r 2 @ 3.9 ´ 10 33 ergs s -1 7 -1 Bolometric Luminosity only measured for the Sun Note that.: 1 watt = 10 ergs s W K 11 M od02 ASTRONOMY – C.E. WOODWARD 29 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 30 29 30 Energy Generation In The Sun Energy Generation In The Sun Solar Neutrinos Solar Neutrinos Released In The pp-chain Massless (Or Very Nearly Massless) Particle That Rarely Interacts With Matter Pass Through Matter Freely (Weakly Interacting, “Massless” Particles) Once Created In Core Of Sun Stream Out At Speed Of Light (If Massless) Or Nearly Speed Of Light (Some Mass) If We Understand Fusion (pp-chain) Can We Indirectly Detect The Neutrinos 𝜈𝜈! Electron Neutrinos are created in the pp-chain Could Tell You About Process In The Interior Of Sun On Timescales Of 8.5 mins SNU Detectors — Since Rarely Interact With Matter First Attempted By Davis And Collaborators In The H omestake Gold Mine In Lead, SD Neutrino Could Pass Thru One-light Year Of Lead And Not Be Stopped Dakota 37 Examine Your Pinky Finger Isotope Of CL Isotope Of Argon Several Trillion Neutrinos Pass Through Per Second N eutrino Weak Force Interaction with Matter Observed SNU Flux ≈ 3x to 4x Smaller Than Standard Solar Models Neutrino “Flavors” Or Neutrino “Oscillations” W K 11 M od02 ASTRONOMY – C.E. WOODWARD 31 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 32 31 32 8  11/12/24 Copyright © 2024 C.E. Woodward. All rights reserved. For U. Minnesota AST1001 Fall 2024 student use exclusively (enrolled individuals). Electronic dissemination, web postings, social media posting, pay-wall site posting, class-notes website postings, etc. is strictly prohibited. Energy Generation In The Sun Energy ENERYGeneration GENERATIONIn—The SUNSun Solar Neutrinos Neutrino Problem Super-Kamiokanda Neutrino Experiment Neutrinos come directly from the core of the Sun, a product of the proton-proton chain. 3000 Metric Tons Of Pure Water And Phototubes Water M olecules Flash W hen They Occasionally We have detected them, proving that the theory of nuclear fusion reactions is correct Interact With Neutrino Detectors Are About The Size Of Beach-balls But we only detect about 30% - 50% of the neutrinos which are predicted by theoretic models. ü either our understanding of nuclear fusion reactions or our understanding of neutrinos is wrong Super-K neutrino image: The grid shows the full sky centered on he Sun making it clear that the Sun is the source of these neutrinos We have since discovered three types of neutrinos: ü electron (ne), muon (nµ), and tau (nt) Neutrino Detectors Need To Be Buried Deep Within Rock To Shield Detectors ü our neutrino detectors can register only electron neutrinos From Energetic Particles Called Cosmic Rays Super-K — First To Detect Neutrinos From SN1987a If neutrinos can change type after being created, this could solve (solved in early 2000s) the “neutrino problem.” Neutrinos provide a direct way to measure nuclear fusion in the Sun and the results h ttp s://w w w.y o u tu b e.c o m /w a tc h ? v = sE IU v jp 3 JIE indicate that fusion occurs as our model basically predict W K 11 M od02 ASTRONOMY – C.E. WOODWARD 33 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 34 33 34 Energy Generation In The Sun Solar Activity Solar Neutrinos Fermilab muon neutrino experiment MINOS first witnessed neutrino oscillations in 2006. The MINOS Far Detector is located in Soudan, MN 735 km from the Fermilab linear accelerator near Chicago, IL. W K 11 M od02 ASTRONOMY – C.E. WOODWARD 35 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 36 35 36 9  11/12/24 Copyright © 2024 C.E. Woodward. All rights reserved. For U. Minnesota AST1001 Fall 2024 student use exclusively (enrolled individuals). Electronic dissemination, web postings, social media posting, pay-wall site posting, class-notes website postings, etc. is strictly prohibited. Solar Activity Photosphere Features — Sunspots Dark Central Region Of Planet-sized Sunspot -- Image Resolution 100 km Convection Combined with Differential Rotation ─ Cause of Solar Activity Gas Motions Twist, Stretch, and Distort the Embedded Solar Magnetic Fields 00:09 Sunspots: Linked to Solar Activity, Solar Flares, & Large Gas Loops Extending into the Corona (2002 July 15 / Swedish Solar Telescope — La Plama) W K 11 M od02 ASTRONOMY – C.E. WOODWARD 37 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 38 37 38 Photosphere Features — Sunspots Photosphere Features — Sunspots Magnetic Fields Lines Of Force Lines Of Force Go Between Opposite Poles Penumbra Per Unit Area 5000 kilom eters Poles Come In Pairs 5000 kilom eters Umbra We draw magnetic field lines (red) to represent the Cool Regions Result When Strong Magnetic Fields Prevent Convection From invisible magnetic fields (field line represent Force). Transporting Heat From The Interior W K 11 M od02 ASTRONOMY – C.E. WOODWARD 39 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 40 39 40 10  11/12/24 Copyright © 2024 C.E. Woodward. All rights reserved. For U. Minnesota AST1001 Fall 2024 student use exclusively (enrolled individuals). Electronic dissemination, web postings, social media posting, pay-wall site posting, class-notes website postings, etc. is strictly prohibited. Photosphere Features — Sunspots Photosphere Features — Sunspots Sunspots — Zeeman Effect Sunspots — Zeeman Effect Zeeman spitting demonstrated by using a “neon-disk” increasing the magnetic field from 0 to 0.8 Tesla ( OKAYAMA ASTROPHYSICAL OBSERVATORY) https://www.youtube.com/watch?v=K57NQZgDFKI In The Presence Of Magnetic Field Energy Levels “Split” Degree Of Splitting Proportional To Magnetic Field Strength W K 11 M od02 ASTRONOMY – C.E. WOODWARD 41 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 42 41 42 Photosphere Features — Sunspots Photosphere Features — Sunspots M aunder M inimum — This period of solar inactivity also corresponds to a climatic period called the "Little Ice Age" 5000 kilom eters 5000 kilom eters when rivers that are normally ice-free froze and snow fields remained year-round at lower altitudes. There is evidence that the Sun has had similar periods of inactivity in the more distant past. The connection between solar activity and terrestrial Solar Activity —Spot Cycle Period ≈ 11 Years (Flip of Magnetic Field Polarity) climate is an area of on-going research. Perhaps Spot Cycle Related To Solar Luminosity Variations ? “Butterfly Diagram” https://solarscience.msfc.nasa.gov/SunspotCycle.shtml Solar Luminosity ─ 0.1% or Less Annual Variation W K 11 M od02 ASTRONOMY – C.E. WOODWARD 43 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 44 43 44 11  11/12/24 Copyright © 2024 C.E. Woodward. All rights reserved. For U. Minnesota AST1001 Fall 2024 student use exclusively (enrolled individuals). Electronic dissemination, web postings, social media posting, pay-wall site posting, class-notes website postings, etc. is strictly prohibited. Photosphere Features — Sunspots Photosphere Features — Sunspots Sunspots Associated With Solar Flare Regions Solar Flares Violent Solar Activity Gigantic Outbursts Of Charged Particles, Visible, UV And X-ray Photons Effect On Earth ─ “Space Weather” 5000 kilom eters Disrupt Radio Communications 5000 kilom eters Power Blackouts “Fry” Satellites FLARE Brilliant Aurora ( YOHKOH SOFT XRAY TELESCOPE — SIGMOID EVENT ) W K 11 M od02 ASTRONOMY – C.E. WOODWARD 45 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 46 45 46 Photosphere Features — Sunspots Photosphere Features — Sunspots Magnetic Field Line Wind-up ― Solar Dynamo Outstanding questions facing solar physicists is the origin of the solar magnetic cycle W hat drives the 11-year sunspot cycle? Sun's meridional circulation is a5000 kilom eters massive flow pattern that transports hot plasma near the 0:26 surface from the solar equator to the poles and back to the equator in the deeper layers of the convection zone, similar to a "conveyor belt". Soon after the instruments opened their doors, the Sun began performing for the Solar Dynamics Observatory (SDO) with this beautiful FLARE prominence eruption. This AIA data is from March 30, 2010, showing a wavelength band that is centered around 304 Å. This extreme The structure and strength of this meridional flow is believed to play a key role in ultraviolet emission line is from singly ionized Helium, or He II, and corresponds to a temperature of approx. 50,000 degrees Celsius. The determining the strength of the Sun's polar magnetic field, which in turn determines the second movie shows a prominence with larger field of view strength of the sunspot cycles. W K 11 M od02 ASTRONOMY – C.E. WOODWARD 47 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 48 47 48 12  11/12/24 Copyright © 2024 C.E. Woodward. All rights reserved. For U. Minnesota AST1001 Fall 2024 student use exclusively (enrolled individuals). Electronic dissemination, web postings, social media posting, pay-wall site posting, class-notes website postings, etc. is strictly prohibited. Photosphere Features — Sunspots Solar Wind Magnetic Field Line Wind-up ― Solar Dynamo Solar Wind Supersonic Flow Into Interplanetary Space Of Plasma From The Corona Comprised Of Approximately Equal Numbers Of Electrons And Ions Ions — 95% Protons, Some Doubly Ionized H e, Trace Of Metals Embedded In The Solar Wind — Weak Magnetic Field Known As The Interplanetary M agnetic Field (IM F) Solar Wind — Density, Velocity, Temperature — Varies With Solar Cycle Types of Solar Wind Average Values Measured At Orbit Of Earth a Density ≈ 8.7 Proton per cubic centimeter -1 a Velocity ≈ 468 km s aB-field ≈ 6.6 nano-Tesla 00:13 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 49 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 50 49 50 Solar Wind Solar Wind ( YOHKOH X-RAY IMAGE ) Solar Wind Coronal Holes The stream of electrons, protons, H elium nuclei and other ions which flow out from the Sun. It extends out beyond Pluto. (Courtesy of SOHO consortium SOHO is a project of ESA & NASA) X-ray image of corona Coronal H oles are Regions Of UV image of solar wind Low Coronal Temperature And Density M agnetic Field Weak (Open Field Lines) Visible image of solar wind During Decline And Minimum Of Solar Cycle Comet SOHO-6 (fell into Sun) -1 H igh-speed ( 500 – 800 km s ) Winds Flow From Coronal H oles Sagittarius Coronal Holes Largest At Solar M inimum W K 11 M od02 ASTRONOMY – C.E. WOODWARD 51 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 52 51 52 13  11/12/24 Copyright © 2024 C.E. Woodward. All rights reserved. For U. Minnesota AST1001 Fall 2024 student use exclusively (enrolled individuals). Electronic dissemination, web postings, social media posting, pay-wall site posting, class-notes website postings, etc. is strictly prohibited. Solar Wind Solar Wind Coronal Holes Coronal Mass Ejections ( LASCO/SOHO IMAGE)) CM E E V E N T 19 9 6 J A N 15 3.5RSUN Eruptions Into Interplanetary Space Of Billions Of Tons Of Plasma And Embedded Magnetic Fields From The Sun’s Corona Transient Phenomena (Unlike Steady-state Solar Wind) 02:15 Originate From Regions W here There Is Catastrophic Disruption Of Large-scale Coronal Magnetic Structures (Coronal Streamers) W K 11 M od02 ASTRONOMY – C.E. WOODWARD 53 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 54 53 54 Solar Wind Space Weather Coronal Mass Ejections 00:37 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 55 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 56 55 56 14  11/12/24 Copyright © 2024 C.E. Woodward. All rights reserved. For U. Minnesota AST1001 Fall 2024 student use exclusively (enrolled individuals). Electronic dissemination, web postings, social media posting, pay-wall site posting, class-notes website postings, etc. is strictly prohibited. Space Weather Space Weather Audio recording of Aurora – Natural ELF-VLF Radio frequencies recorded at Grass River Provincial Park in central-western Manitoba, Canada on 30 August 1996 at 1652 UTC For more sounds see: http://www-pw.physics.uiowa.edu/mcgreevy/ Aurora Closely Correlated With Solar Activity H igh Energy Particles Trapped In Earth’s Magnetic Field Spiral Into The Upper Atmosphere, Colliding With And Excite Atoms And Molecules Color In Aurora Related To Density Of Oxygen And Nitrogen As Function Of Altitude In Earth’s Atmosphere W K 11 M od02 ASTRONOMY – C.E. WOODWARD 57 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 58 57 58 Space Weather Aurorae ( C re d it: S.M e n d e & H.F re y , S S I/U C B e rk e le y ) “Extreme” G5-class Auroral Storm Imaged Over the N-pole By A NOAA FUV Satellite During A Major Geomagnetic Storm (2000 Jul 15-16). Emission Is From N 2 W K 11 M od02 ASTRONOMY – C.E. WOODWARD 59 59 15