1

ASTR 1040 ASTR 1040 AccelAccel AstroAstro:: Stars & GalaxiesStars & Galaxies

Prof. Prof. JuriJuri ToomreToomre TA: Nicholas NelsonTA: Nicholas NelsonLecture 8 Lecture 8 ThurThur 3 Feb 20113 Feb 2011

zeus.colorado.edu/astr1040zeus.colorado.edu/astr1040--toomretoomre

SolarSolargranulationgranulation

Today +Today +•• The solar neutrino puzzleThe solar neutrino puzzle, and how resolved, and how resolved

•• Granulation:Granulation: intensely turbulent convection near intensely turbulent convection near the solar surfacethe solar surface

•• Helioseismology: Helioseismology: using sound waves to probe the using sound waves to probe the solar interiorsolar interior

•• Solar Solar magnetismmagnetism and its remarkable cycles in and its remarkable cycles in next lecturenext lecture

•• Start reading in Start reading in detaildetail Chap 15: Surveying the Chap 15: Surveying the StarsStars

Meanderings of outbound photonsMeanderings of outbound photonsPP--P chain makes P chain makes gammagamma--ray photonsray photons, which , which ““random walkrandom walk””outwards (getting absorbed, reoutwards (getting absorbed, re--emitted), gradually emitted), gradually coolingcooling

Takes light aboutTakes light aboutone million yearsone million yearsfrom creationfrom creationto getting outto getting out

REMINDERREMINDER

Heading outward Heading outward (slow & fast)(slow & fast)

Gamma raysGamma rays slowly slowly work their way work their way outwards, cool, and outwards, cool, and become become ““sunlightsunlight””(about million years)(about million years)

NeutrinosNeutrinos dondon’’t interact t interact with much, zoom right with much, zoom right out of Sun and into out of Sun and into space,space, carry ~2% of carry ~2% of the Sunthe Sun’’s energys energy ––even travel right through even travel right through the Earth!the Earth!

Reading Clicker Q Reading Clicker Q

•• If the SunIf the Sun’’s core went out of balance and s core went out of balance and shrank a little, what would happen there?shrank a little, what would happen there?

•• A.A. Density would decrease and fusion would Density would decrease and fusion would slow downslow down, releasing less energy, releasing less energy

•• B.B. Density and temperature would increase and Density and temperature would increase and fusion would fusion would speed upspeed up, releasing more energy, releasing more energy

•• C.C. The The wholewhole Sun would eventually shrink and Sun would eventually shrink and thus core would come back into balancethus core would come back into balance

•• D.D. Not much would really change, so Not much would really change, so nothing to nothing to worry aboutworry about

B.B.DiscussionDiscussion

•• How do we really How do we really knowknow what is what is happening deep within the Sun?happening deep within the Sun?

•• What is interplay between theory What is interplay between theory and observation?and observation?

2

Temperature and density with radiusTemperature and density with radius

from from ““stellar stellar structurestructure”” theory,theory,helioseismologyhelioseismology

ProtonProton--Proton (PProton (P--P) ChainP) ChainThermonuclear FUSIONThermonuclear FUSION

Two Two ““electronelectron”” neutrinos produced neutrinos produced

Those Mysterious Those Mysterious Neutrinos Neutrinos

•• MassMass--less or with very small masses,less or with very small masses, travel travel close to speed of lightclose to speed of light

•• DonDon’’t interact (almost) with other matter:t interact (almost) with other matter:requires lead wall 1 light year thick to stop a requires lead wall 1 light year thick to stop a neutrino! neutrino!

•• Lots of them:Lots of them: 10103838 neutrinos/sec from the Sun, neutrinos/sec from the Sun, 65 billions/cm65 billions/cm22/sec /sec coming through coming through YOU !YOU !

•• But we can still catch some, using massive But we can still catch some, using massive underground underground ““detectorsdetectors””: : BIG PUZZLEBIG PUZZLE

MADE BY PMADE BY P--P BURNING IN COREP BURNING IN CORE

PP--P chain and electron neutrinosP chain and electron neutrinos

REMINDERREMINDER

““Feynman diagramFeynman diagram””

betabeta---- decaydecay: a neutron : a neutron ““decaysdecays”” into a protoninto a protondown quark down quark up quarkup quark

Solar neutrino energy spectrumSolar neutrino energy spectrum

ppIIIppIII

pppp

3

Big PuzzleBig Puzzle: Catching Solar Neutrinos: Catching Solar Neutrinos

•• Located deep underground, Located deep underground, rock blocking other particlesrock blocking other particles

•• Huge underground vat of Huge underground vat of drydry--cleaning fluidcleaning fluid

•• Chlorine captures neutrino, Chlorine captures neutrino, becomes radioactive argonbecomes radioactive argon

•• Only collects 1 neutrino Only collects 1 neutrino about every 3 daysabout every 3 days ---- even even with 100,000 gallonswith 100,000 gallons

•• Solar theory predicted Solar theory predicted THREE TIMES more!THREE TIMES more!

•• Big hunt started, calledBig hunt started, calledSOLAR NEUTRINO SOLAR NEUTRINO PROBLEMPROBLEM HomestakeHomestake Gold Mine SDGold Mine SD

Visionary: Ray DavisVisionary: Ray Davis

Resolving the Solar Neutrino PuzzleResolving the Solar Neutrino Puzzle

•• SuperSuper--KamiokandeKamiokande uses massive uses massive tank of water to capture neutrinostank of water to capture neutrinos

•• Each rare capture gives flash of Each rare capture gives flash of light, detected by giant tubeslight, detected by giant tubes

•• Captures lower energy neutrinos Captures lower energy neutrinos from from pp--pp chain, so more sensitive chain, so more sensitive test of fusiontest of fusion

•• Suggests some Suggests some electron neutrinoselectron neutrinosmay change into may change into muonmuon and tau and tau neutrinosneutrinos during course of flight to during course of flight to us (8 minutes)us (8 minutes)

•• MSW MSW Neutrino OscillationsNeutrino Oscillationsrequire neutrinos to have some require neutrinos to have some mass!mass!

KamiokandeKamiokande Nickel Mine, JapanNickel Mine, Japan

Sudbury Neutrino ObservatorySudbury Neutrino Observatory (SNO)(SNO)•• Uses Uses ““heavy waterheavy water”” ----

one H in Hone H in H220 replaced 0 replaced by its stable isotope by its stable isotope deuterium (P+N)deuterium (P+N)

•• SNO is capturing SNO is capturing all all three types of neutrinosthree types of neutrinos(electron, (electron, muonmuon, , taotao))

•• ““Solar neutrino problemSolar neutrino problem””leads to big physics leads to big physics advance advance (2002 Nobel Phys (2002 Nobel Phys Prize; Davis & Prize; Davis & KoshibaKoshiba))

Sun Viewed by SuperSun Viewed by Super--KamiokandeKamiokande

500 day500 day““exposureexposure””

Clicker Clicker –– Doppler shifts?Doppler shifts?•• Star moving Star moving away from usaway from us at 0.01 the speed of at 0.01 the speed of

light emits a spectral line with a wavelength of 600 light emits a spectral line with a wavelength of 600 nanometers (nm). What is the nanometers (nm). What is the observedobservedwavelength of that line?wavelength of that line?

•• A.A. 606 nm606 nm

•• B.B. 600.6 nm600.6 nm

•• C. C. 594 nm594 nm

•• D.D. 596.4 nm596.4 nm

•• E.E. 600 nm600 nm

A.A.

v/c/

Convection Zone and Convection Zone and RadiativeRadiative InteriorInterior

Deep shell (30%) Deep shell (30%) of very turbulent of very turbulent

convectionconvection

Drives strong Drives strong differential rotationdifferential rotation

Just below theJust below thephotosphere:photosphere:

But But how how do do we know this?we know this?

4

GRANULATIONGRANULATIONVISIBLE ATVISIBLE ATSURFACESURFACE

``Roiling and boiling``Roiling and boiling’’’’at the surface ! at the surface !

Smallest scale of Smallest scale of solar convectionsolar convection

Granulation:Granulation: turbulent convectionturbulent convection

Size: ~ 1 Mm acrossSize: ~ 1 Mm across

SunspotSunspot(2 July 2010)(2 July 2010)surrounded bysurrounded byGRANULATIONGRANULATION

BBSO NST AOBBSO NST AO

Granulation in actionGranulation in action

BBSOBBSO1.6m NST1.6m NSTadaptive adaptive opticsoptics

Helioseismology:Helioseismology: Millions of sound Millions of sound waves available to probe solar interiorwaves available to probe solar interior

ACOUSTIC WAVESACOUSTIC WAVES

Some waves noodleSome waves noodlejust below the surfacejust below the surface

Others almost make itOthers almost make itto the centerto the center

All excited by turbulentAll excited by turbulentgranulation visible ingranulation visible inphotospherephotosphere

BONGO DRUMS and BONGO DRUMS and SOLAR TONESSOLAR TONES

HOW THE LENGTH OF DRUMHOW THE LENGTH OF DRUMCONTROLS THE TONE (FREQUENCY)CONTROLS THE TONE (FREQUENCY)

5

How Sound Makes A Surface BounceHow Sound Makes A Surface Bounce

•• Sound waves inside Sun cause the Sound waves inside Sun cause the photosphere to move up and downphotosphere to move up and down, with , with ““fivefive--minute oscillationsminute oscillations””

•• Can detect these with Doppler imaging of Can detect these with Doppler imaging of gas at solar surface (gas at solar surface (““seesee”” the sound)the sound)

DEMONSTRATE BIG VIBRATING DRUMHEADDEMONSTRATE BIG VIBRATING DRUMHEAD

Tools of Imaging HelioseismologyTools of Imaging Helioseismology

SOHO Spacecraft SOHO Spacecraft Michelson Doppler Imager ( MDI )Michelson Doppler Imager ( MDI )

Global Oscillation Network Group ( GONG )Global Oscillation Network Group ( GONG )

Doppler movie of solar surface from SOHODoppler movie of solar surface from SOHO

2020oo acrossacross

SOLARSOLAROSCILLATIONOSCILLATIONMODEMODE

One of millionsOne of millionsof modes, each with of modes, each with a different tone!a different tone!

Probing the interior with Probing the interior with helioseismologyhelioseismology

GLOBAL ACOUSTIC WAVESGLOBAL ACOUSTIC WAVES INTERNAL GRAVITY WAVEINTERNAL GRAVITY WAVE

…… helping to resolve some of the dynamicshelping to resolve some of the dynamics““Power SpectrumPower Spectrum”” of Solar Oscillationsof Solar Oscillations

Each oscillationEach oscillationmode has a mode has a distinctivedistinctive(measurable) tone(measurable) tone

Sensitive to howSensitive to howsound speed variessound speed varieswith depthwith depth

Tests models ofTests models ofinside temperature inside temperature

Observed from Observed from SOHO and GONGSOHO and GONG

FREQUENCYFREQUENCY