The Sun, the stars and their surroundings Flashcards
How does the volume of a gas relate to its pressure at a constant temperature?
The volume of the gas is inversely proportional to its pressure as the pressure of a gas is the frequency at which molecules hit the sides of the container so less space means this happens more often and the pressure is larger
How does temperature affect the pressure upon a volume of gas?
Pressure is how often molecules hit the sides of their container and temperature is the energy they have and how fast the molecules move. So if temperature increases then the molecules will hit the sides more frequently and pressure increases
How can we tell that pressure and volume relate to the absolute temperature (temp in kelvin)?
If we plot the volume at different temperatures on a graph we find that a straight line is produced, this line starts on the graph where volume is 0, when volume is 0, temperature is -273*C which is absolute 0
What are the three gas laws for their three inter-related properties: pressure, volume and temperature?
Pressure/temperature = constant Pressure *volume = constant Volume/temperature = constant They can be combined as: (Pressure*volume)/temperature = constant
How do molecules behave at absolute 0?
At absolute 0 molecules should not move at all
How can we find specific elements line spectra?
A photon of light is emitted when an electron drops from one energy level to another, every element has its own set of allowed energy levels so the energy produced all have different emission spectra
How are protostars formed?
Gravity pulls the gas and dust, from huge nebula clouds, together and as the cloud collapse GPE becomes KE and so temperature increases forming dense and not so dense regions. The regions that aren’t dense collapse and eventually form hot, glowing red protostars
Why does temperature increase as gas clouds collapse?
As they collapse inwards they become denser, this decreases the volume and then in combination with the increased speeds of molecules the temperature and pressure increases until pressure rebalances with gravity and it becomes stable
How does the sun get its energy?
Through nuclear fusion, the fusion of hydrogen into helium, hydrogen must first combine to form an isotope of hydrogen called deuterium which then form helium
What else is produced in formation of deuterium and why?
A positron and neutrino is also produced, the positron is produced to conserve charge through the products and reactants
Energy is liberated from fusing of light nuclei to make heavy nuclei with masses up to that of what elements nucleus?
Energy is liberated with nucleus’ that have a mass up to that of the iron nucleus
What is used to calculate the energy released during fusion and fission?
Einstein’s equation E=mc^2 is used to calculate energy released, where E is energy produced, m is the mass lost and c is the speed of light in a vacuum
What happens to the products of fusion as a star becomes more massive?
The more massive the star, the hotter its core and the heavier the nuclei it can create by fusion
Where does most fusion take place and why?
Most fusion takes place in the core as this is where the temperature and density are highest
How does energy get from the core of a star out into space?
Energy is taken from the core to the surface by photons and convection where it is radiates into space from the photosphere
How does the element used and produced by fusion at a stars core change with its stage?
In the main sequence, hydrogen forms by fusion to make helium, but as its core runs out of hydrogen it swells to become a red giant/supergiant where helium produces carbon and heavier nuclei in fusion
What happens at the end of a low mass stars life?
At the end of helium fusion it lacks the mass to further compress the core and so shrinks to a white dwarf
What happens at the end of a high mass stars life?
In a high mass star nuclear fusion can produce heavier nuclei and when the core is mostly this heavy nuclei, it explodes as a supernova creating nuclei with larger mass than iron and leaving a neutron star or black hole
What happens in a white dwarf star?
Nothing, there is no nuclear fusion, the star just gradually cools down and fades
What evidence is there to suggest for and against extraterrestrial life?
There is currently no evidence of extraterrestrial life but scientists thinks it’s likely that life exists somewhere in the universe if it is infinite and there are other stars surrounded by planets
