The Sun
THE SUN
The Sun is the star at the center of the Solar System. It is spherical in shape has a diameter of about 1,392,000 km, which is about 109 times that of Earth and its mass about 2×1030 kilograms which is 330,000 times is that of Earth. Accounts for about 99.86% of the total mass of the Solar System. The Sun fuses 620 million meric tons of hydrogen each second. The Sun is now thought to be brighter than about 85% of the stars in the Milky Way Galaxy. The Sun's hot corona continuously expands in space creating the solar wind. The Sun is currently traveling through the Local Interstellar Cloud in the Local Bubble zone, within the inner rim of the Orion Arm of the Milky Way galaxy. The mean distance of the Sun from the Earth is approximately 149.6 million kilometers (1 AU).
What is the age of the Sun ?
>Well, the Sun has been active for 4.6 billion years and has
enough fuel to go on for another five billion years or so.
The Sun's outer visible layer is called the photosphere and has atemperature of 6,000°C (11,000°F). This layer has a mottled appearance
due to the turbulent eruptions of energy at the surface.
What will happen then ?
>The Sun will start to fuse helium into heavier elements and begin to swell up, ultimately growing so large that it will swallow the Earth. After a billionyears as a Red Giant, it will suddenly collapse into a White Dwarf -- the final end product of a star like ours.
It may take a trillion years to cool off completely.
Properties:
Radius = 100 x Earth (696,000 km)
Mass = 300,000 x Earth (1.99 x 1030 kg)
Surface temp = 5780 K
Core temp = 15,000,000 K
Luminosity = 4 x 1026 Watts
Solar “Day” =
24.9 Earth days (equator)
29.8 Earth days (poles)
The composition of the sun is:
 |
| Inside |
Core = 20 x density of iron
Surface = 10,000 x less dense than air
Average density = Jupiter
Core = 15,000,000 K
Surface = 5780 K
In the core :
Density = 20 x density of Iron
Temperature = 15,000,000 K
Hydrogen atoms fuse together Create Helium atoms.
A list of the mass distribution within our Solar System :
Sun: 99.85% of all the matter in the Solar System.
Planets: 0.135% condensed out of the same disk of material that formed the Sun.
Comets: 0.01%
Satellites: 0.00005%
Minor Planets: 0.0000002%
Meteoroids: 0.0000001%
Interplanetary Medium: 0.0000001%
The Sun support life on Earth.
>The Sun provides energy for photosynthesis, which releases oxygen into the atmosphere.
>The greenhouse effect trap some of the solar energy on Earth, keeping it warm (at the right temperature for us).
>The Sun ultimately determines the fate of the life on Earth.
>The Sun is the only star that we can study in details.
>The Sun is the test bed for our theory of the stars.
THE CORE :
The core of the Sun is considered to extend from the center to about 20–25% of the solar radius. It has a density of up to 150 g/cm (which is about 150 times the density of water) and a temperature of close to 15.7 million kelvin. The Sun's surface temperature is approx 5,800 K. The core is the only region in the Sun that produces an amount of thermal energy through fusion inside 24% of the Sun's radius, 99% of the power has been generated, and by 30% of the radius, fusion has stopped nearly entirely.
The rest of the star is heated by energy that is transferred outward from the core and the layers just outside. The energy produced by fusion in the core must then travel through many successive layers to the solar photosphere before it escapes into space as sunlight or kinetic energy of particles.
Energy production: About 3.6×1038 protons (hydrogen nuclei) are converted into helium nuclei every second and releasing mass and energy at the mass-energy equivalence rate of 4.3 million tonnes per second, 380 yottawatts (3.8×1026 watts), equivalent to 9.1×1010 megatons of TNT per second.
The core produces almost all of the Sun's heat via fusion .The energy production per unit time (power) produced by fusion in the core varies with distance from the solar center. At the center of the sun, fusion power is estimated by model to be about 276.5 watts/m3.
The photosphere:
The visible surface of the Sun, the photosphere is the layer below which the Sun becomes opaque to visible light. Above the photosphere visible sunlight is free to propagate into space and its energy escapes the Sun entirely. The change in opacity is due to the decreasing amount of H− ions, which absorb visible light easily. The photosphere is tens to hundreds of kilometers thick and slightly less opaque than air on Earth because the upper part of the photosphere is cooler than the lower part.
The Sun's photosphere has a temperature between 4500 and 6000 K.The Sun's photosphere is composed of convection cells called granules—cells of gas each approximately 1000 kilometers in diameter.
The X-Ray sun :
Q: At 1,000,000 K where does a blackbody spectrum have its peak?
A: X-rays
Can monitor the Solar Coronasphere in the X-ray spectrum.
Monitor Corona
Chromosphere :
The chromosphere (literally, "sphere of colour") is the second of the three main layers in the Sun's atmosphere and is roughly 2 000-kilometers deep. It sits just above the photosphere and just below the solar transition region
Very low density
But also very hot
Same as the gas tubes we saw in class and lab.
Energy from below excites the atoms and produces emission from this layer.
Predominant element – Hydrogen.
Brightest hydrogen line – Ha.
Chromosphere = color
The core of the Sun is considered to extend from the center to about 20–25% of the solar radius. It has a density of up to 150 g/cm (which is about 150 times the density of water) and a temperature of close to 15.7 million kelvin. The Sun's surface temperature is approx 5,800 K. The core is the only region in the Sun that produces an amount of thermal energy through fusion inside 24% of the Sun's radius, 99% of the power has been generated, and by 30% of the radius, fusion has stopped nearly entirely.
The rest of the star is heated by energy that is transferred outward from the core and the layers just outside. The energy produced by fusion in the core must then travel through many successive layers to the solar photosphere before it escapes into space as sunlight or kinetic energy of particles.
Energy production: About 3.6×1038 protons (hydrogen nuclei) are converted into helium nuclei every second and releasing mass and energy at the mass-energy equivalence rate of 4.3 million tonnes per second, 380 yottawatts (3.8×1026 watts), equivalent to 9.1×1010 megatons of TNT per second.
The core produces almost all of the Sun's heat via fusion .The energy production per unit time (power) produced by fusion in the core varies with distance from the solar center. At the center of the sun, fusion power is estimated by model to be about 276.5 watts/m3.
The photosphere:
The visible surface of the Sun, the photosphere is the layer below which the Sun becomes opaque to visible light. Above the photosphere visible sunlight is free to propagate into space and its energy escapes the Sun entirely. The change in opacity is due to the decreasing amount of H− ions, which absorb visible light easily. The photosphere is tens to hundreds of kilometers thick and slightly less opaque than air on Earth because the upper part of the photosphere is cooler than the lower part.
The Sun's photosphere has a temperature between 4500 and 6000 K.The Sun's photosphere is composed of convection cells called granules—cells of gas each approximately 1000 kilometers in diameter.
The X-Ray sun :
A: X-rays
Can monitor the Solar Coronasphere in the X-ray spectrum.
Monitor Corona
Chromosphere :
The chromosphere (literally, "sphere of colour") is the second of the three main layers in the Sun's atmosphere and is roughly 2 000-kilometers deep. It sits just above the photosphere and just below the solar transition region
Very low density
But also very hot
Same as the gas tubes we saw in class and lab.
Energy from below excites the atoms and produces emission from this layer.
Predominant element – Hydrogen.
Brightest hydrogen line – Ha.
Chromosphere = color
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