ch 11 the sun
the sun is
a star, a luminous ball of gas and plasma that is more than 100 times bigger than the Earth
what generates energy in the sun?
fusion
what is big ivan
largest dentation on entire earth done by the Russians in 1961
The Convection Zone
Above the radiative zone, energy is more efficiently transported by the rising and sinking of gas: • This region is called the convection zone - convection zone= to oven in your house
Strong Nuclear Force:
- Holds positively charged nucleus together
electromagnetic force:
- Inverse square law with distance - Proportional to electric charge strength - Opposite charges attract and like charges repel
Gravitational Force:
- Inverse square law with distance - Proportional to mass - Always attractive
Weak Nuclear Force:
- Involved in radioactive decay
how the sun works
- Structure of the Sun depends on a balance between its internal forces - specifically, a hydrostatic equilibrium between a force that prevents the Sun from collapsing and a force that holds it together -The inward (holding) force is the Sun's own gravity, while the outward (non-collapsing) force arises from the Sun's internal gas pressure -Without balance the Sun would rapidly change
solar winds
- a tenuous gas of hydrogen and helium that sweeps across the entire Solar System -500 kilometers per second
solar cycle
-Sunspot, flare, and prominence activity change yearly in a pattern called the solar cycle -The cycle may vary from 6 to 16 years - Considering the polarity direction of the sunspots, the cycle is 22 years, because the Sun's magnetic field reverses at the end of each 11 year cycle -Leading spots in one hemisphere have the same polarity, while in the other hemisphere, the opposite polarity leads
differential rotation
-The Sun undergoes differential rotation of 25 days at the equator and 30 days at the poles - the sun is a ball of gas with strange fluid so it has differential rotation
The Chromosphere
-The lower part of the atmosphere is referred to as the chromosphere • The chromosphere appears as a thin red zone around the dark disk of a totally eclipsed Sun • The red is caused by the strong red emission line of hydrogen Hα • The chromosphere contains millions of thin columns called spicules, each a jet of hot gas
what is prominence
-loops that connect the sun spots -Prominences are huge glowing gas plumes that stick out from the lower chromosphere into the corona
coronal mass ejection
-spewing things out there -it's like projectile vomiting -sun does this whether it's active or not
Granulation
Convection manifests itself in the photosphere as granulation, numerous bright regions surrounded by narrow dark zones
sunspots
Dark-appearing regions ranging in size from a few hundred to a few thousand kilometers across • Last a few days to over a month • Darker because they are cooler than their surroundings (4500 K vs 6000 K) • Cooler due to stronger magnetic fields within them
Important Facts
Every second, about 4.26 million metric tons of hydrogen are converted to pure energy: -The total energy emitted from the Sun that strikes the face of the Earth each second is about the same as was generated during the "Big Ivan" 50 Mt hydrogen bomb detonation • Helium is currently the "ash" left over during this process. • Peak power production in the Sun has been compared to the volumetric heats generated in an active compost pile: -The tremendous power output of the Sun is not due to its high power per volume, but instead due to its large size
the maunder minimum
Few sunspots existed from 1645-1715, the Maunder Minimum, the same time of the "little ice age in Europe and North America
Flare and CME Comparison
Flares and CMEs are both associated with high energy particles: - In the case of a CME, coronal material is ejected into space at high speeds - Both flares and CMEs depend on magnetic fields on the Sun • Flares are local events as compared to CMEs which are much larger eruptions of the corona.
Solar Flares
Strong increase in radio and x-ray emissions • Intense twisting and "breakage" of magnetic field lines is thought to be the source of flares • Some flare eruptions can explosively shoot gas across the Solar System and result in spectacular auroral displays
what is the photosphere
The low density upper layers of the Sun, where any photons created there can freely escape into space -The photosphere is yellow "surface" we see with our eyes -Layers below the p h o t o s p h e r e are opaque, photons created there are readily absorbed by atoms located there
1 gram of mass =
strength of nuclear weapon
Solar Seismology
the study of the Sun's interior by analyzing wave motions on the Sun's surface and atmosphere - E. Fermi coined the name neutrino meaning "little neutral one" -The wave motion can be detected by the Doppler shift of the moving material -The detected wave motion gives temperature and density profiles deep in the Sun's interior -These profiles agree very well with current model
identify the 4 forces: strongest and weakest
weakest: gravitational weak nuclear force- radioactive decay electromagnetic force- static shock strongest- strong nuclear force
Coronal Mass Ejection
• A coronal mass ejection (CME) is a massive burst of solar wind, other light isotope plasmas, and magnetic fields rising above the corona or being released into space
solar neutrinos
• Neutrinos lack electric charge, have a very small mass, escape the Sun's interior relatively unaffected, and shower the Earth (about 1 trillion pass through a human per second) -warm matter -artifact of the decaying process -scientists put neutrinos underground; came from nuclear fusion from stars that were here before us
the radiative zone
• Photons created in the Sun's interior do not travel very far before being reabsorbed • Energy created in the Sun's center will take about 16 million years to eventually diffuse to the surface!
Pressure in the Sun
• Pressure in a gas comes from atomic collisions • The amount of pressure is in direct proportion to the speed of the atoms and their density and is expressed in the perfect or ideal gas law
The Radiative Zone
• Since the core is hotter than the surface, heat will flow outward from the Sun's center • Near the Sun's center, energy is moved outward by photon radiation: - a region surrounding the core known as the radiative zone
The Corona
• Temperature in the corona eventually reaches about one million K (not much energy though due to low density) • The corona, visible in a total solar eclipse, can be seen to reach altitudes of several solar radii • The corona is not uniform but has streamers and coronal holes dictated by the Sun's magnetic field how the sun works: energy wants to get out and gravity forces it the other way -balance bwtn balance and pressure
Properties of the Sun
• The Sun's distance from Earth (about 150 million km or 1 AU) was once measured by triangulation, but is now done by radar • Once the distance is known, its diameter (about 1.4 million km) can be found from its angular size (about 0.5 degree) • From the Sun's distance and the Earth's orbital period, Kepler's modified third law gives the Sun's mass • Mass and radius, the surface gravity of the Sun is found to be 30 times that of Earth • Next, the surface temperature (5780 K) is found from the Sun's color and the use of Wien's law for a blackbody
The Solar Interior
• Theoretical calculations show that the Sun's surface temperature and density both increase as the core is approached: - The density is similar to that found at sea level on Earth at the Sun's surface and 100 times that of water at the core
Solar Atmosphere
•The density of the atmosphere decreases steadily with altitude and eventually merges with the near-vacuum of space •Immediately above the photosphere, the temperature of the atmosphere decrease but at higher altitudes, the temperature grows hotter, reaching temperatures of several million Kelvin •The reason for the increase in temperature is unknown, but speculation is that Sun's magnetic field plays an important role