Layers of the Sun!
What is the source of the sun’s energy?
Nuclear fusion!! - the process of combining nuclei of small atoms to form a more massive nuclei
Sunspots are regions of:
Intense magnetism. This is caused by the movement of gases within the convective zone in combination with the movements caused by the suns rotation. These areas are darker in color and cooler in temperature.
Stars appear to move in circular paths through the sky because:
What are circumpolar stars?
And, what accounts for the different stars being seen in the sky during different seasons of the year?
Stars appear in circular paths through the sky because the Earth rotates on its axis.
Circumpolar stars are stars that never pass below the horizon in either their nightly or annual movements. They appear to circle Polaris (the North Star).
Different stars are seen during different seasons because Earth revolves around the sun.
A nebula begins the process of becoming a protostar when the nebula:
begin to shrink and increase its spin. Scientists theorize that this occurs due to an outside force such as an explosion or supernova which compresses the cloud of gas.
What is apparent magnitude and how do you read its scale?
Apparent magnitude - The brightness of a star as seen from the Earth. The lower the number, the brighter the star.
Describe the temperature gradient of the various layers of the sun
Hottest in the core, cool off as it is further away from the core, then rises again as it moves out through the atmospheric layers
Sudden outward eruption of electrically charged particles from the sun are called __________.
Solar activity is largely a result of __________.
Solar flares! These eruptions are believed to be linked to the sunspot cycle and release the energy stored in the strong magnetic fields of sunspots. They may travel upward thousands of kilometers in minutes and usually do not last more than an hour. They increase the solar wind.
Solar activity is caused by the changing solar magnetic field and aligns with the sunspot cycle. (It is not caused by the suns intense heat)
List the color of the stars from hottest to coolest:
What color is our sun?
Blue, white, yellow, orange, red
Our sun is a yellow star! Other stars of that same color will have similar temperatures because color is an indicator of temperature. Yellow stars have a surface temperature of about 5,500 degrees C.
A main sequence star generates energy by fusing:
Hydrogen into helium. This is called nuclear fusion.
What is a lightyear? What does this mean when we view the light from that star? Are we seeing the star as it is at that moment? Or are we seeing how it was in the past?
A lightyear is the distance that light travels in one year. It travels about 9.46 trillion km in one year. This means that the light we see from a star that is 430 light-years away (Polaris) is seen the way it was 430 years in the past.
Which layer of the sun transfers energy to the surface through the rising and sinking of gases?
The convective zone! - Energy is transferred within this zone through convection (the transfer of energy by moving matter)
Why are sunspots cooler than the surrounding areas of the sun's surface?
The strong magnetic fields in sunspot regions (produced by the movement of gases within the convective zone in combo with the movements caused by the rotation of the sun), cause the gases within the convective zone to slow. This causes a decrease in the amount of gas transferring energy from the core to the photosphere which in turn causes these regions to be up to 3,000 degrees C cooler than surrounding areas.
The change in position of a nearby star as seen from different points on Earth's orbit compared with the position of a far away star is called:
Parallax
Which is denser: a white dwarf or a neutron star?
What is the heaviest element formed in the core of a star?
How do black holes form?
A Neutron Star is denser!!!
The heaviest element formed within the core of a star is iron!
A black hole is an object that is so massive and dense that even light cannot escape it's gravity. It forms from a massive star whose remaining core is contains more than 3 times the mass of the sun. The star contracts even further under its gravity (past the neutron star phase) to become a black hole. They always result from a super nova!!
List two differences between a quasar and a pulsar.
Quasars appear as a point of light in the night sky but are not actually stars. The are more closely related to galaxies. Many project a jet of gas deep into the universe. They are located in the center of galaxies that are extremely distant from Earth. Their centers are very bright and may have a large black hole in their center. A galaxy with an extremely bright center and a blackhole.
Pulsars are neutron stars that rotate extremely quickly. They emit a beam of radio waves that sweep across space like a lighthouse. They are commonly surrounded by the remnants of a supernova.
Describe the photosphere!
* Gives off visible energy
* Temperature is cooler than the layer below
* Layer of the sun that is visible from Earth
* Innermost layer of the sun's atmosphere
* Means sphere of light (not sphere of color)
* Location of solar activity
What causes a geomagnetic storm and its potential consequence? When should we expect auroras to be most intense?
Coronal Mass Ejections or parts of the corona which are thrown off into space (solar wind - ionized gases) cause disruptions in Earth's magnetosphere (the space around Earth that contains a magnetic field). These are called geomagnetic storms. Geomagnetic storms can interfere with radio communications on Earth, damage satellites, may lead to blackouts when power lines become overloaded, and create beautiful and colorful auroras at the poles of the Earth
Auroras are colored light produced by charged particles from the solar wind and from the magnetosphere that react with and excite the oxygen and nitrogen of Earth's upper atmosphere. These occur throughout the year but are most intense after coronal mass ejections which occur due to solar activity on the photosphere typically at the peak of the sunspot cycle. These are seen at the poles of the Earth.
The spectrograph that can be used to analyze stars is called ___________
How do stellar spectra reveal that the stars are actually moving?
The spectrograph that is used to analyze stars is dark-line spectra (not bright-line spectrum)
The stellar spectra reveals doppler shifts either toward the red end of the spectrum (red-shift) or toward to blue end of the spectrum (blue shift) depending on whether or not the star is moving toward or away from the Earth.
What happens to main sequence stars like the sun when energy from fusion is no longer available?
They collapse and form white dwarfs (not neutron stars or super giants).
What is the difference between a nova and a supernova?
Nova - A main sequence stars remnants (a white dwarf) which explodes as it accumulates gas and on its surface from a neighboring red giant star. It then builds in pressure as its gravity pulls the gases inward which leads to a large explosion (a nova). This star suddenly becomes brighter. A nova typically happens with stars in a binary system where a white dwarf is revolving around a red giant. This may happen over and over in a binary system.
Supernova - A star that has such a tremendous explosion that it blows itself apart. In a binary star system, mass accumulates of the surface of a white dwarf and gravity overwhelms the outward pressure. The star collapses and becomes so dense that its outer layers rebound and collapse outward. They are thousands of times more violent then novas and completely destroy the white dwarf.
In massive stars, this is a regular part of their lifecycle. After the supergiant stage in a massive stars lifecycle the gravity overwhelms the outward pressure, it collapses and the star explodes into a supernova (unlike the main sequence star which explodes as a planetary nebula). What is left is a neutron star.
What are the three layers of the sun’s atmosphere and give one fact each. Also, which layer is the layer that can be seen only during a total solar eclipse?
Photosphere - innermost layer of the suns atmosphere, means "sphere of light", made up of gases that have risen from the convective zone, temperature is about 6,000 degrees C, most energy given off is in the form of visible light, the layer seen from Earth, the location of solar activity
The chromosphere - means "color sphere", thin layer that glows with a reddish light which is the color given off by hydrogen, temperature ranges from 6,000-50,000 degrees C, gases are moving away from the photosphere, jets of gases frequently shoot through and form the chromosphere, middle layer of the suns atmosphere
Corona - outer layer of the suns atmosphere, means "crown", thin zone where the temperature rises dramatically, temperatures are above 1,000,000 degrees C, its magnetic field is strong enough to stop most subatomic particles from escaping into space, source of the solar wind, may only be seen during a total solar eclipse
C
When are the number of sunspots at their highest?
Sunspots reach a peak in number about halfway through their 11 year cycle. They are at their lowest at the beginning and end of the 11 year cycle.
If a star shows a red shift it is moving _________
If a star shows a blue shift it is moving _________
A red shift shows a star is moving away from Earth.
A blue shift shows a star is moving toward the Earth.
A star maintains its stable size because of stellar equilibrium which states:
The inward force of gravity is balanced by the outward pressure from nuclear fusion and radiates inside the star.
A main sequence star that is greater than 8x's the mass of our sun and ten times hotter than our sun is most likely _______ in color will follow lifecycle of a ________ star.
List out the stages of this stars lifecycle.
The star will likely be blue or white in color and will follow a massive stars lifecycle.
Nebula --> Protostar --> Massive Star (in this case a blue or white color) --> Red Supergiant --> Supernova --> Neutron Star