the sun, our favorite star!
DESCRIPTION
The Sun, our favorite star!. WE CAN SEE IT REALLY WELL. The Sun is the basis for all of our knowledge of stars. Why?. Kelvin Temperature Scale. Today we will take a journey from the center of the Sun, starting just outside the core…. …and ending up deep in the corona. - PowerPoint PPT PresentationTRANSCRIPT
The Sun, our favorite star!
WE CAN SEE IT REALLY WELL.
The Sun is the basis for all of our knowledge of stars. Why?
temperature kelvin degree Celsius degree Fahrenheit
symbol K °C °F
boiling point of water 373.15 100. 212.
melting point of ice 273.15 0. 32.
absolute zero 0. -273.15 -459.67
Humans 310 37 98.6
Sun 5800 5527 9980
Kelvin Temperature Scale
Today we will take a journey from the center of the Sun, starting just outside the core…
…and ending up deep in the corona.
Overview of Solar Structure(aka, our Sun as a jawbreaker)
Main Parts:
Corona
Chromosphere Photosphere
Convection Zone
Radiative Zone
Core
The Sun is made of mostly HYDROGEN and HELIUM
Rotation
25 Days at the Equator35 Days at the Poles
This twisting leads to the loopy structures we see!
The CoreFusion takes place here.
Fusion Animation http://astro.unl.edu/classaction/animations/sunsolarenergy/fusion01.html
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+ Energy4H 1He
The interior of the Sun…
• Energy is generated in the core, but how does it get out and end up as sunshine?
The next two layers of the Sun are all about getting the energy being made in the core out
into space!
How does energy get from one place to another?
1. Convection
3. Radiative Diffusion
2. Conduction
Convection and Radiative Diffusion are most important for the Sun!
Radiative Diffusion
The photons “diffuse”
outwards, heating the gas
as they go.• Photons can “scatter” off of
unbound electrons• When they scatter, the photons
share their energy with the electrons
• The electrons get hotter
Ionized gas
The Radiative Zone
Ionized gas
Here, photons bounce around in a
“random walk”
Eventually they make it out of the
radiative zone, but it takes a long, long
time!
Convection
Hot stuff rises…
Cool stuff sinks!
Hot water goes up to the surface while cool water sinks down -- cool water then gets heated and rises
a.k.a: BOILING
The Convective Zone
The Convective Zone is the layer just under the photosphere
Convective “cells”:As seen from the top, these are the granules we
see in the photosphere
Photosphere
Conduction
Metal of the pan heats by conduction…
…heat travels through the atoms
of the pan Not very important for stars!
PHOTOSPHERE
Characteristics• the part of the sun we see•one of the coolest parts at 6000K•densest part of solar atmosphere •contains sun spots, granules (ation)
Photosphere temperature is about 5800 K…
• Remember how the temperature and color of stars are related? The temperature of our Sun gives it its yellowish color!
Our Sun is really yellowish green, but our atmosphere absorbs and scatters some of the blue light.
The photosphere has some interesting features too…
Sunspots:Regions where magnetic field pokes
through the photosphere.Sunspots are cooler than surrounding
stuff, so they look dark!
Granules:Where the roiling, boiling convection zone
underneath bubbles up.
Sunspots• dark cooler (4000K vs. 5800K) regions on the sun• last several days to several weeks• caused by the sun’s magnetic field upwelling to the photosphere• occur in cycles• contribute to solar storms such as flares and coronal mass ejections
Sunspot pairsDescribe what you seein this image to someonein class
Explain what you see in this picture tosomeone else in class.
Granulation•Cover the sun’s surface•approx. 1000km across (Texas sized)• tops of convection cells•white centers are hotter than dark edges•flow can be up to 15000 mph• individual cells last 20 min
http://www.youtube.com/watch?v=zxzhfijFML8&feature=related
CHROMOSPHERE
Characteristics• red color due to hydrogen emission lines• temperature 4500K to 10000K•prominences form here •2500 km thick• spicules (jets of plasma) form here
Spicules• small jet like eruptions that last a few minutes• send material out into corona at 20-30 km/s
TRANSITION REGION• Region of rapid temperature change between chromosphere and corona
THE CORONA• temperature 1-3 million K•very irregularly shaped• strong x-ray emitter•uncertain as to why it is so hot•coronal holes are the origin of the solar wind•produces an absorption and continuous spectrumhttp://www.nasa.gov/mission_pages/sunearth/news/colorful-science_prt.htm
Coronal Mass Ejections
• Huge bubbles of gas ejected from the sun• Can cause problems with communications• Often occur with flares
SOLAR WIND
• low density gases (ionized hydrogen)• travels 300 to 1000km/s• sun loses 10,000,000 tons of mass
per year
Current Solar WindData can be found atwww.spaceweather.com
