The Origin of Solar System
The Origin of Solar System Yudhiakto Pramudya, Ph.D Astronomy
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QS Fushshilat 41:11
Then He turned straight to the sky, while it was a smoke, and said to it and to the earth, ‘Come (to my obedience) both of you, willingly or unwillingly.” Both said, We come willingly
QS Al-Sajdah 32:4
Allah is the One Who created the heavens and the earth and all that is between them in six days, then He positioned Himself on the Throne. Other than Him, there is neither a guardian for you, nor an intercessor. Would you then not observe the advice?
Nebular hypothesis by Emmanuel Swedenborg, Kant (1755) and developed by Laplace and others. Another model :
Catastrophe theories, isolated sun had a close encounter with another star Sun and planets formed separately In the 1970’s, Soviet Astronomer Victor Safronov proposed the Solar Nebular Disk Model (SNDM). The solar system originated from the collapse of a large gas cloud, some 4.6 years billion years ago. A small part of a giant molecular cloud experienced a gravitational collapse. It begins to spin faster because of angular momentum conservation. The time scale for the initial collapse is
6 roughly 10 years. The collapsing, spinning nebula begins to flatten into a rotating pancake.
As the nebula collapses further, local regions begin to contract gravitationally on their own because of instabilities in the collapsing rotating cloud.
Due to the Sun’s radiation, the inner Solar System was too warm for volatile molecules like water and methane to condense. Planetesimals which formed there were relatively small and composed largely of compounds with high melting points, such as silicates and metals. The terrestrial planets : Mercury, Venus, Earth, Mars The minor planets or asteroids, due to gravitational effect of Jupiter
As the temperature fell further away from the Sun, volatile icy compounds could remain solid-beyond what is called the frost line. Jupiter and Saturn captured far more material than the terrestrial planets and overlaying their icy/rocky core were layers of metallic and molecular hydrogen. Jupiter and Saturn become gas giants and contain the largest percentages of hydrogen and helium. Uranus and Neptunus captured much less material. Ice giants Their cores are mostly made of ice which is overlain by molecular hydrogen and gases such as ammonia, methane, and CO. Basic features of Solar System : The planets orbits lie nearly in a plane with the sun at the center The planets all revolve in the same direction The planets mostly rotate in the same direction with the rotation axes nearly perpendicular to the orbital plane
Solar System composition
Initially hydrogen and helium silicon, iron, lithium, etc. The heavier elements formed much later in the interiors of stars
Diameter Diameter = R θ, with R is the distance Sun-Earth, θ is about 30 arcmin in the sky Mass
2 MmG mv
=
2πR v =
P
2
3 R
4π M
=
2 GP
Density
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3 Volume
= πr
3 M Density
=
V angular diameter = linear diameter distance The angular diameter unit is radian, you need to convert it to degree.
The conversion is 1 radian = 180 / π degrees.
Wien’s Displacement Law λ max = b/T b = 2.897x10 −3 m K
Stefan-Boltzmann Law σ = 5.67x10 −8 Wm −2 K −4
E = σAT
4 The atmosphere of the Sun : Corona : Thin gases and are visible only during total solar eclipse.
Chromosphere : The transparent gases. Photosphere : The Visible Surface. The Pictures show the (a) the scale of the Earth and Chromosphere and Photosphere and (b) the Corona are visible during the eclipse. Photosphere
The photosphere is less than 500 km deep. The average temperature is about 5800 K. The density is low. It is about 34000 less than the air. The air at
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sea level and 15C is 1.225 kg/m Below the photosphere is denser and hotter
Solar flare and prominence The layer of the sun Sunspots appears darker region since the the temperature are cool spots on the sun surface. They are about 4240 K, compared to the photosphere temperature that is about 5800 K. They often appears in pairs or groups. Each spot has a central umbra surrounded by a lighter penumbra.
The Sun rotation at the equator has period of 28 days and 35 days near the Sun’s poles. The difference in the periods drag the magnetic field so the equatorial part leading compared to the pole. The tangled of the magnetic field loops can rise to the surface and produces Sunspots
Sunspot number reaches a peak after 3-4 years (max) then begins to reduce for 7-8 years (min). The process then stars over again, is called the sunspot cycle. The average of the sunspot cycle is 10.5 - 11 years.
Magnetic Field is 0.15 - 0.3 Tesla compared to earth magnetic field is between 25 to 65 microTesla one of the theory to explain the temperature of sunspot is the strong magnetic field stops the convection below the surface Prominence
Bright columns of gas are often seen stretching up from the chromosphere into the corona. The are caused by dense ionized gas that is suspended by the Sun’s magnetic field but rains back from the corona into chromosphere
Flare
Originating in the Sun’s corona The breaking and reconnection of the Sun’s magnetic field lines and the resulting release of magnetic energy. The energy up to 1 billion megatons of TNT Tend to occur above the active regions around sunspots Tend to be more frequent at the time of solar maximum Coronal mass ejections, which are the ejection of material from the solar corona consisting largely of electrons and proton with smaller quantities of heavier elements The stream of highly energetic particles take 15 min to reach the Earth It can pose a threat to astronouts and destroyed satellite sub-systems
The solar wind existence was deduced from observations of the tails of comets. The dust tail that is composed of grains material that are released as the Sun sublimates ice from the surface of the comet nucleus. The dust particles feel radiation pressure from the Sun and are pushed away from the Sun. The ion tails is composed of ionized molecules, such as cyanogen (CN 2 ) and CO. If the Sun emitting a stream of charged particles would interact with the ions Momentum transfer and driving tail ions away from the Sun Aurora
Colored light display in north (Aurora Borealis) and south (Aurora Australis) magnetic poles It is caused by collision of charged particles with atoms high in the Earth’s upper atmosphere.
Reading
http://csep10.phys.utk.edu/astr161/lect/solarsys/nebular.html http://www.universetoday.com/77525/nebular-theory/ http://csep10.phys.utk.edu/astr161/lect/index.html Lecture notes on Astronomy PH2900-2007/2008 Introduction to Astronomy and Cosmology