Lecture 6: Fiske Planetarium #1

1/30/20

ASTR 1040: Stars & Galaxies Topics for Today (pre-show) • Start with how Sun is put together • Why is a star spherical, and does not collapse? (Gravitational equilibrium) • Why does it shine, and must it shine? What is the energy source? (Fusion of H to He)

• Complete detail read Chap 14 (Our Star) Solar Prominence from SOHO EIT • Read S4.1, S4.2 (quarks, leptons, ..) • New Homework #3 (The Sun) passed out, HW #2 Prof. Juri Toomre TAs: Max Weiner, Loren Matilsky to be turned in, HW #1 returned graded Lecture 6 Thur 30 Jan 2020 • Observatory Night #1 tonight, but forecast dubious zeus.colorado.edu/astr1040-toomre

Today’s NY Times Next to Our Nearest Star Chap 14

Late Edition Today, sunshine mixing with clouds, seasonably cold, high 37. Tonight, cloudy, low 31. Tomorrow, sunshine and some clouds, not as cold, high 44. Weather map is on Page A32.

Fear of Flood if Dam Lining Up Votes to Opens Just a Crack Block Witnesses

WASHINGTON — In the end, By SHERYL GAY STOLBERG the impeachment calculation and MICHAEL D. SHEAR nearly all Senate Republicans WASHINGTON — The White are making is fairly simple: They House and Senate Republicans would rather look like they ig- worked aggressively on Wednes- nored relevant evi- day to discount damaging revela- TRUMP dence than plunge tions from John R. Bolton and line the Senate into an up the votes to block new wit- ON TRIAL unpredictable, open- nesses from testifying in Presi- ended inquiry that CARL dent Trump’s impeachment trial, HULSE would anger Presi- in a push to bring the proceeding dent Trump and to a swift close. court political peril. As the Senate opened a two-day, As Republicans on Wednesday 16-hour period of questioning lined up behind blocking wit- from senators, Mr. Trump laced nesses in the trial, their reason- into Mr. Bolton, his former na- ing reflected the worry that tional security adviser, whose un- allowing testimony by John R. published manuscript contains an Bolton, the former national secu- account that contradicts his im- rity adviser whose unpublished peachment defense. The presi- manuscript contradicts a central dent described Mr. Bolton on Twit- part of Mr. Trump’s impeach- ter as a warmonger who had ment defense, would undoubt- “begged” for his job, was fired, edly lead to a cascade of other and then wrote “a nasty & untrue witnesses. book.” They in turn could provide On Capitol Hill, Mr. Trump’s more damaging disclosures and aides circulated a letter informing NSO/NSF/AURA tie up the Senate indefinitely, Mr. Bolton that the White House when the ultimate verdict — an was moving to block publication of The Sun’s Churning Face all but certain acquittal of the A telescope in Hawaii has captured the most detailed view yet, revealing cell-like “kernels,” each about the size of Texas. Page A23. president — is not in doubt. “For the sake of argument, one could assume everything attrib- utable to John Bolton is accurate, and still the House would fall Outside China, well below the standards to Plan Leaves Palestinians With Few Options remove a president from office,” said Senator Lindsey Graham, By DAVID M. HALBFINGER With only muted reaction from Racing to Halt Republican of South Carolina. and ISABEL KERSHNER Arab neighbors, a struggling Republicans have offered Bid That Favors Israel Palestinian economy, little appar- Virus’s Spread JERUSALEM — For Mah- myriad rationales for refusing moud Abbas, the ailing octoge- Deprives Abbas of All ent appetite among Palestinians new testimony: Gathering it was narian president of the Palestin- for a violent response and the the House’s job Calling more H’ F h F

Pull of gravity = Push of pressure gradient

Big Qs about the Sun (and any star)

SPHERICAL

nature of gravity

• Why is a star ROUND ? makes it ROUND

• What keeps a star from collapsing

inward ?

• What keeps it shining ? • Why does it rotate and have varying magnetic fields ? High PRESSURE needed at CENTER

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Gravitational How to get high central pressure? equilibrium In gases, plasmas, equation of state is roughly

PRESSURE vs GRAVITY PRESSURE = DENSITY x TEMPERATURE

1. Making the CENTER HOT yields high pressure that keeps star from collapsing

2. If really hot, NUCLEAR BURNING can supply the HOT CENTER energy that always leaks away from hot places

Reading Clicker Q D. • What is the composition (by mass) of OVERVIEW of the Sun the Sun ? • A. 100% hydrogen (H) and helium (He) • B. 50% H, 25% He, 25% other elements Sun is round, • C. 70% He, 28% H, 2% other rotates, • D. 70% H, 28% He, 2% other burns H • E. 98% H, 2% He and other to He

SUN IN Big System View of Sun PROFILE SURFACE photosphere core Vast range radiative zone in temperature CORE convection zone and density - - - - - photosphere chromosphere chromosphere corona ATMOSPHERE solar wind corona

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Convection Zone and Radiative Interior

Sun is a big ball of plasma Just below the photosphere: • Hydrogen and helium are ionized by the high temperature throughout most of star Deep shell (30%) • Such electrically-conducting GAS is called of very turbulent a PLASMA convection

Drives strong • Movement of plasma has currents flowing, differential rotation builds magnetic fields and electric fields

DKIST First Light

In close up

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Complex Interplay of Convection and Magnetism Solar Dynamics Observatory ( SDO ) MDI offspring: Helioseismic & Magnetic Imager ( HMI )

1m Swedish Solar Telescope

1 Mm spacing on ticks Launched Feb 2010 (4096x4096)

EUV and Visible Images Evolving Magnetism

AIA 171 Å HMI Dopplergrams (Low Corona ~ 6x105 K) (Photosphere ~ 5000 K)

NOW TO PLANETARIUM SKY

with full-dome flythrough to our location within the spiral arm of our galaxy, visit to M51 for reality check on star-birth regions in spiral arms, visiting splendid images of nebulosities and explicit star-birth regions including Orion in different wavelength bands

and then turn to full-dome Lucas production “Solar Superstorms”