The Solar InteriorLACC: §14.3, 15.2, 15.3

• Know what powers the sun

• Understand the Solar Neutrino Problem

• Know the Solar interior

An attempt to answer the “big questions”: what is the sun? how does it effect us?

1Thursday, April 15, 2010

The Sun: Wow! Sheet

http://www.solarviews.com/eng/sun.htm

Mass (tons) 2.19x1027

Mass (Earth = 1) 332,830Equatorial radius (km) 695,000Equatorial radius (Earth = 1) 108.97Mean density (gm/cm3) 1.41Rotational period (days)! 25-36*Escape velocity (km/sec) 618.02Luminosity (ergs/sec) 3.83x1033

Magnitude (Vo) -26.8Mean surface temperature! 10,800°FCore temperature! 27,000,000°FCore density (gm/cm3) 150Core pressure (atm) 340,000,000,000Age (billion years) 4.5

Principal chemistry (1.) Hydrogen 92.10% Helium 7.80% Oxygen 0.061% Carbon 0.030% Nitrogen 0.084% Neon 0.076% Iron 0.0037% Silicon 0.0031% Magnesium 0.0024% Sulfur 0.0015% All others 0.0015%1. % by # of atoms abundances

* The Sun's period of rotation at the surface varies from approximately 25 days at the equator to 36 days at the poles. Deep down, below the convective zone, everything appears to rotate with a period of 27 days.

Energy generated in the Sun's core takes a million years to reach its surface. Every second 700 million tons (1/(3 billion billionth) of the sun’s total mass) of hydrogen are converted into helium ash. In the process 5 million tons of pure energy is released; therefore, as time goes on, the Sun is getting lighter.

2Thursday, April 15, 2010

The Proton-Proton Chain

http://astro.unl.edu/classaction/loader.html?filename=animations/sunsolarenergy/fusion01.swf&movieid=fusion01&width=550&height=550&version=6.0.0

3Thursday, April 15, 2010

The Atom, e.g. He4

http://www.bio.miami.edu/~cmallery/150/chemistry/c8.2x5.helium.jpg

4Thursday, April 15, 2010

Subatomic Particles of Interest

Particle Symbols Charge Mass

Protons p, p+, 1H, H+ +1 1.0073

Neutrons n, n0 0 1.0087

Electrons e, e+, β+ -1 0.0005

Positron e-, β- +1 0.0005

Neutrino ν 0 0?

Gamma Ray γ 0 0

Alpha Particle α, 4He, He2+ +2 4.0015

5Thursday, April 15, 2010

p-p Chain: Energy Production

http://zebu.uoregon.edu/~soper/Sun/fusion.html

The evidence is strong that the sun is "burning" H to make He:4H + 2e- --> He4 + 2 neutrinos + 6 photons

In this reaction, the final particles have less internal energy than the starting particles. Since energy is conserved, the extra energy is released as energy of motion of the nuclei and electrons in the solar gas, the production of photons [pure energy] and, finally, the energy of the neutrinos, which just zip right out of the Sun. That is the gas gets hotter and has lots of photons (and neutrinos). The amount of energy involved is 26 MeV (26 million eV) each time the reaction above happens. (By comparison, CH4 + 2O2 --> CO2 + 2H2O results in 5.5 eV of energy.)Why do we think that this is what goes on? • Energy output of millions of eV per reaction is needed if the Sun has been producing energy at the observed rate over billions of years. • The reactions exist. (They have been studied in the laboratory.) • There is a consistent step-by-step theory for the reaction.

Davison E. Soper, Institute of Theoretical Science, University of Oregon, Eugene OR 97403 USA soper@bovine.uoregon.edu

6Thursday, April 15, 2010

Solar Neutrino Problem

Super-Kamiokande, a neutrino detector in Japan, holds 50,000 tons of ultrapure water surrounded by light tubes.

http://www.scidacreview.org/0601/html/astro.html

7Thursday, April 15, 2010

Solar Neutrino Problem

http://www.cora.nwra.com/~werne/eos/text/neutrino.html

Over the years scientists have considered two possible explanations of the solar neutrino problem:1. Perhaps we don't

understand the Sun well enough. Maybe a better theory of the internal structure of the Sun would predict fewer neutrinos, in agreement with the measurements.

2. Perhaps we don't understand neutrinos well enough; maybe they have some features beyond the standard theory of neutrinos that account for the problem.

8Thursday, April 15, 2010

The Solar Neutrino Problem

http://conferences.fnal.gov/lp2003/forthepublic/neutrinos/index.html

Particles in the Standard Model of particle physics: The Standard Model contains 3 neutrinos of definite flavor, and a set of corresponding anti-particles.

9Thursday, April 15, 2010

Hydrostatic Equilibrium

http://physics.uoregon.edu/~jimbrau/astr122/Notes/Chapter16.html

10Thursday, April 15, 2010

Solar Interior

http://sprg.ssl.berkeley.edu/%7Eabbett/sun1.html

11Thursday, April 15, 2010

The photons produced in nuclear reactions take about a million years to move from the core to the surface. The photons scatter off the dense gas particles in the interior and move about a centimeter between collisions. In each collision they transfer some of their energy to the gas particles. By the time photons reach the photosphere, the gamma rays have become photons of much lower energy---visible light photons. Because the photons now reaching the surface were produced about a million years ago, they tell us about the conditions in the core as it was a million years ago. The other particle produced in nuclear reactions has a less tortuous path out of the core.

A neutrino is a massless (or very nearly massless) particle that rarely interacts with ordinary matter. Neutrinos travel extremely fast---the speed of light if they have zero mass or very close to the speed of light if they have a small mass. Because they travel so fast and interact so rarely with matter, neutrinos pass from the core of the Sun to the surface in only two seconds. They take less than 8.5 minutes to travel the distance from the Sun to the Earth. If you could detect them, the neutrinos would tell you about the conditions in the Sun's core as it was only 8.5 minutes ago (much more current information than the photons!).

Solar Interior

http://www.astronomynotes.com/starsun/s4.htm

12Thursday, April 15, 2010

Solar Core

http://fas.org/irp/imint/docs/rst/Sect20/A5a.html13Thursday, April 15, 2010

Solar InteriorCore

•p-p chain occurs

•convection

Radiative zone

•photon random walk

• radiation

Convection zone

•convection cells

•convection

Radiation

•photons travel

•vacuum, gasses

Convection

•bulk fluid flow

• liquid, gasses

Conduction

• individual molecules collide

•solids

14Thursday, April 15, 2010

The Solar InteriorLACC: §14.3, 15.2, 15.3

• Know what powers the sun: Nuclear Fusion, the p-p chain, 4H + 2e- --> He4 + 2 ν + 6 γ

• Understand the Solar Neutrino Problem: It seems that neutrinos can change flavor

• Know the Solar interior: core, radiative zone, convection zone, photosphere

An attempt to answer the “big questions”: what is the sun? how does it effect us?

15Thursday, April 15, 2010

• Ch 15, p354: #4

• Ch 14: Tutorial Quizzes accessible from: http://www.brookscole.com/cgi-brookscole/course_products_bc.pl?fid=M20b&product_isbn_issn=9780495017899&discipline_number=19

• Ch 15: Image Analysis Quizzes accessible from: http://www.brookscole.com/cgi-brookscole/course_products_bc.pl?fid=M20b&product_isbn_issn=9780495017899&discipline_number=19

Due beginning of next class period.

HW: Franknoi, Morrison, and Wolff, Voyages Through the Universe, 3rd ed.

16Thursday, April 15, 2010

Solar Surface and AtmosphereLACC: §14.3, 15.2, 15.3

• Know the sun’s atmosphere

• Know solar surface features

• Know how the sun affects the earth

An attempt to answer the “big questions”: what is the sun? how does it effect us?

17Thursday, April 15, 2010

Solar Atmosphere

http://rst.gsfc.nasa.gov/Sect20/A5a.html

K = Kelvin°C = Celsius

°F = Fahrenheit

K = °C + 273.15°F = 1.8°C + 32°

So, at high temperature,°F ≅ 1.8°C

At very high temperatures,°F ≅ 1.8K

18Thursday, April 15, 2010

Solar Features

http://ircamera.as.arizona.edu/NatSci102/lectures/sun.htm

19Thursday, April 15, 2010

Solar Features: Sunspots

http://www.astro.wisc.edu/~sparke/ast103/lecture11.html

http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question17.html

Granules are individual convection cells.

20Thursday, April 15, 2010

Solar Features: Sunspots

http://www.windows.ucar.edu/tour/link=/sun/atmosphere/sunspots.html&edu=high

Sunspots are dark, planet-sized regions that appear on the "surface" of the Sun. Sunspots are "dark" because they are cooler than their surroundings. A large sunspot might have a central temperature of 4,000 K (about 3,700° C or 6,700° F), much lower than the 5,800 K (about 5,500° C or 10,000° F) temperature of the adjacent photosphere. Sunspots are only dark in contrast to the bright face of the Sun. If you could cut an average sunspot out of the Sun and place it elsewhere in the night sky, it would be about as bright as a full moon. Sunspots have a lighter outer section called the penumbra, and a darker central region named the umbra.Sunspots form over periods lasting from days to weeks, and can persist for weeks or even months before dissipating. The average number of spots visible on the face of the Sun is not constant, but varies in a multi-year cycle. Historical records of sunspot counts, which go back hundreds of years, verify that this sunspot cycle has an average period of roughly eleven years.

http://www.windows.ucar.edu/tour/link=/sun/images/

sunspots_earth_size_big_jpg_image.html&edu=high

21Thursday, April 15, 2010

Solar Features: Sunspot Cycle

http://www.windows.ucar.edu/tour/link=/sun/activity/solar_variation.html

Although astronomers have observed the fairly regular rise and fall of sunspot counts in this 11-year cycle for several centuries, there have also been disruptions in this pattern. The largest well-documented disruption was an era that lasted from about 1645 to 1715 during which almost no sunspots were seen. This long lull is known as the Maunder Minimum. Curiously, Europe and parts of North America were struck by spells of remarkably cold weather at roughly the same time.

22Thursday, April 15, 2010

Solar Features:Sunspots--Cause

http://ircamera.as.arizona.edu/NatSci102/lectures/sun.htm

Sunspots are magnetic -- they occur in pairs where one is a north pole while the other is a south pole. Every 11 years, the more western parts of sunspot pairs will change from magnetic N to magnetic S (or vice versa). (From Chaisson & McMillan, Astronomy Today)

23Thursday, April 15, 2010

Solar Features: Sunspots and Magnetism

http://www.windows.ucar.edu/tour/link=/sun/atmosphere/sunspot_form_jpg_image.html&edu=high

Every 11 years the sun’s magnetic field snaps back to situation #1. But, when it snaps back, the North and South magnetic poles will be reversed.

So the sunspot cycle is every 11 years, but the solar magnetic field cycle is every 22 years.

24Thursday, April 15, 2010

Solar Features: Prominences (and Filaments)

http://apod.nasa.gov/apod/ap040330.html

One of the most spectacular solar sights is a prominence. A solar prominence is a cloud of solar gas held above the Sun's surface by the Sun's magnetic field. Last month, NASA's Sun-orbiting SOHO spacecraft imaged an impressively large prominence hovering over the surface, pictured above. The Earth would easily fit under the hovering curtain of hot gas. A quiescent prominence typically lasts about a month, and may erupt in a Coronal Mass Ejection (CME) expelling hot gas into the Solar System. Although somehow related to the Sun's changing magnetic field, the energy mechanism that creates and sustains a Solar prominence is still a topic of research.

25Thursday, April 15, 2010

Solar Features: Prominences (and Filaments)

http://antwrp.gsfc.nasa.gov/apod/ap040725.html

Hot gas frequently erupts from the Sun. One such eruption produced the glowing filament pictured above, which was captured in 2000 July by the Earth-orbiting TRACE satellite. The filament, although small compared to the overall size of the Sun, measures over 100,000 kilometers in height, so that the entire Earth could easily fit into its outstretched arms. Gas in the filament is funneled by the complex and changing magnetic field of the Sun. After lifting off from the Sun's surface, most of the filamentary gas will eventually fall back.

26Thursday, April 15, 2010

Solar Features: Prominences (and Filaments)

http://www.veoh.com/browse/videos/category/technology/watch/v2191746WPa6CtKC

27Thursday, April 15, 2010

Flares vs Filament (Prominence)

http://soi.stanford.edu/results/SolPhys200/Schrijver/TRACEpodoverview.html

Solar flare (171Å) Solar flare (1600Å) Solar flare (white light)

The two images on the left were taken on 25 June 2000, around 07:37UT (the images were rotated, so that north is to the left). The image on the left shows a filament in the process of being ejected from the Sun, with cool (dark) and hot (bright; around 1.5 million degrees) material at opposite ends of the long, nearly vertical structure.

28Thursday, April 15, 2010

Solar Features: Flares

http://www.windows.ucar.edu/tour/link=/sun/atmosphere/solar_flares.html&edu=high

Solar flares are essentially huge explosions on the Sun. Flares occur when intense magnetic fields on the Sun become too tangled. Like a rubber band that snaps when it is twisted too far, the tangled magnetic fields release energy when they "snap". Solar flares emit huge bursts of electromagnetic radiation, including X-rays, ultraviolet radiation, visible light, and radio waves. The energy emitted by a solar flare is more than a million times greater than the energy from a volcanic explosion on Earth!Although solar flares can be visible in white light, they are often more readily noticed via their bright X-ray and ultraviolet emissions. Coronal mass ejections often accompany solar flares, though scientists are still trying to determine exactly how the two phenomena are related. Solar flares burst forth from the intense magnetic fields in the vicinity of active regions on the Sun. Solar flares are most common during times of peak solar activity, the "solar max" years of the sunspot cycle.

29Thursday, April 15, 2010

Coronal Mass Ejection

http://www.windows.ucar.edu/tour/link=/sun/images/aug1980cme_jpg_image.html

30Thursday, April 15, 2010

Coronal Mass Ejection

http://www.windows.ucar.edu/tour/link=/sun/cmes.html&edu=high

"Without warning, the relatively calm solar atmosphere can be torn asunder by sudden outbursts of a scale unknown on Earth. Catastrophic events of incredible energy...stretch up to halfway across the visible solar surface, suddenly and unpredictably open up and expel their contents, defying the Sun's enormous gravity." (Sun, Earth, and Sky by Kenneth R. Lang)

These catastrophic events that the author is speaking about are coronal mass ejections (CME's).

Coronal mass ejections are explosions in the Sun's corona that spew out solar particles. The CME's typically disrupt helmet streamers in the solar corona. As much as 1x1013 (10 trillion) kilograms of material can be ejected into the solar wind. Coronal mass ejections propagate out in the solar wind, where they may encounter the Earth and influence geomagnetic activity.

CME's are believed to be driven by energy release from the solar magnetic field. How this energy release occurs, and the relationship between different types of solar activity, is one of the many puzzles facing solar physicists today.

31Thursday, April 15, 2010

"Thus, the Sun's sudden and unexpected outbursts remain as unpredictable as most human passions. They just keep on happening, and even seem to be necessary to purge the Sun of pent-up frustration and to relieve it of twisted, contorted magnetism." (Kenneth R. Lang, Sun, Earth and Sky)

CME's can seriously disrupt the Earth's environment. Intense radiation from the Sun, which arrives only 8 minutes after being released, can alter the Earth's outer atmosphere, disrupting long-distance radio communications and deteriorating satellite orbits. Very energetic particles pushed along by the shock wave of the CME can endanger astronauts or fry satellite electronics. These energetic particles arrive at the Earth (or Moon) about an hour later. The actual coronal mass ejection arrives at the Earth one to four days after the initial eruption, resulting in strong geomagnetic storms, aurorae and electrical power blackouts.

http://www.windows.ucar.edu/tour/link=/sun/cmes.html&edu=high

http://ess.nrcan.gc.ca/rrnh-rran/proj3_e.php

Magnetic Storms

32Thursday, April 15, 2010

Solar Wind

http://www.windows.ucar.edu/tour/link=/sun/solar_wind.html&edu=mid

down until they reach the termination shock within the heliosphere. The Heliosphere is the entire region of space influenced by the Sun.

The solar wind plasma is very thin. Near the Earth, the plasma is only about 6 particles per cubic centimeter. So, even though the wind travels SUPER fast, it wouldn't even ruffle your hair if you were to stand in it because it's so thin! But, it is responsible for such unusual things as:

• auroral lights

• fueling magnetospheric storms

The particles of the solar wind, and the Sun's magnetic field (IMF) are stuck together, therefore the solar wind carries the IMF (interplanetary magnetic field) with it into space.

The Sun is flinging 1 million tons of matter out into space every second! We call this material solar wind. Once the solar wind is blown into space, the particles travel at supersonic speeds of 200-800 km/sec! These particles travel all the way past Pluto and do not slow

33Thursday, April 15, 2010

Aurora

http://apod.nasa.gov/apod/ap060329.html

http://www.nasa.gov/centers/goddard/news/topstory/2005/dueling_auroras.html

34Thursday, April 15, 2010

Solar Surface and AtmosphereLACC: §14.3, 15.2, 15.3

• Know the sun’s atmosphere: photosphere (visible), chromosphere (reddish), corona (2 million Kelvin), solar wind (e- and p+’s)

• Know solar surface features: granules, sunspots, prominences, flares, coronal mass ejections

• Know how the sun affects the earth: CME disruption of electronics, aurora

An attempt to answer the “big questions”: what is the sun? how does it effect us?

35Thursday, April 15, 2010

• Ch 14, p354: #5--Prominence, Flare, Coronal Mass Ejection (mention energy, size, and time)

• Ch 15: Image Analysis Quizzes accessible from: http://www.brookscole.com/cgi-brookscole/course_products_bc.pl?fid=M20b&product_isbn_issn=9780495017899&discipline_number=19

• 16, 17: Tutorial Quizzes accessible from: http://www.brookscole.com/cgi-brookscole/course_products_bc.pl?fid=M20b&product_isbn_issn=9780495017899&discipline_number=19

Due beginning of next class period.

HW: Franknoi, Morrison, and Wolff, Voyages Through the Universe, 3rd ed.

36Thursday, April 15, 2010