ASTR 1346 1st Edition Exam 1 Study Guide Lectures 1 8 Lecture 1 January 20 The Sun is a Star Why is the Sun a star The Sun is a star because it gives out its own energy It is a glowing ball of gas held together by its own energy and powered by nuclear fusion at its center How massive is the Sun The Sun is the most massive star in our solar system Mass is the amount of matter an object has The Sun is 333 000 times Earth s mass What is the size of the Sun Size is how much space something takes up physical The Sun is 10 times bigger than Jupiter which is 10 times bigger than Earth What is the Sun s density Density is how much matter is compacted in an object The Sun is about 1 4 th of Earth s density Lecture 2 January 22 Sun Facts What are some facts about the Sun The Sun is 5 800K in surface temp its luminosity is 3 85X10 26 watts its axial tilt is 7 25 degrees it takes about a month to spin on its axis 25 days at the equator 36 days at the polar regions 31 days at 60 degrees latitude The Sun s radius is 700 000km 109 times Earth s radius and 1 AU is 114 years driving to the Sun at 100 mph We see the photosphere of the Sun every day the core is the densest and hottest part of the Sun and the energy of the Sun generates in the Sun s center Lecture 3 January 27 The Sun s Solar Structure Define the core of the Sun The core s about 25 of the Sun s radius the center of the Sun and the hottest part of the Sun Define the radiation zone The radiation zone is when energy diffuses outward in the form of radiation that takes thousands to millions of years Define the convection zone Convection zone is when energy diffuses outwards in the form of convection currents Define the photosphere The photosphere is what we see when we look at the Sun It takes about 170 000 years to travel from the core to the photosphere Define the chromosphere The chromosphere is the lower middle atmosphere and is the coolest place on the Sun Define the corona The corona s the outer atmosphere and very hot 1 2 million K and only visible during eclipses Define solar wind Solar wind is particles from the Sun that permeate the entire solar system Lecture 4 January 29 Heat and Helioseismology Define convection Convection is when heat travels from warmer to cooler objects by circulating air Convection involves liquids and gases Define conduction Conduction is when heat travels from warmer to cooler objects through touch Conduction includes liquids gases and metals Define radiation Radiation is when heat jumps from one object to another and includes all material Define helioseismology Helioseismology is the study of the Sun s waves This is the only way to know about the interior of the Sun because light that we see comes from outside photosphere only Sound is a vibration and moves things up and down and back and forth causing the photosphere to move as well What is GONG GONG Global Oscillations Network Group set up small ground telescopes around the world to continuously observe the Sun What is SOHO SOHO Solar and Heliospheric Observatory sets up telescopes to continuously observe the Sun What is SDO SDO Solar Dynamic Observatory studies the details of the Sun s magnetic field and corona Lecture 5 February 3 Sunspots What is nuclear fusion Nuclear fusion is when one nucleus combines with another nucleus and creates a third nucleus combined with energy The final step in nuclear fusion is when 4 hydrogen nuclei combine and fuse to create 1 helium nucleus plus some energy in the form of gamma rays and 2 neutrinos These gamma rays slowly degrade in energy as they pass through the solar interior Eventually they leave the solar surface in the form of visible light What is the law of conservation of mass and energy E mc 2 is energy mass X speed of light squared This is the law of conservation of mass and energy created by Albert Einstein and explains that matter and energy can t be created nor destroyed but they can be changed in form What are neutrinos Neutrinos carry no electrical charge are very low in mass interact with hardly anything so they escape from the Sun into space and they pass underneath Earth What is the basic composition of our Sun Our Sun is made of plasma which is a state between a solid and a gas with extremely high temperature 67 elements have been identified in the Sun 91 is Hydrogen and the other 9 is Helium What are granules Granules are small cellular features of rising hot gas that cover the entire photosphere Their life time is 5 10 minutes and they re about the size of Texas What are sunspots Sunspots typically measure 10 000km across which is about the size of Earth The darker part of a sunspot is called the umbra and is around 4 500K The lighter part is the penumbra and is around 5 500K Sunspots are slightly cooler than their surroundings which is why they re darker than the rest of the Sun All sunspots occur near the equator What is sunspot maximum and sunspot minimum The Sun may have hundreds of sunspots which is sunspot maximum and is 15 20 degrees away from the equator or none at all which is sunspot minimum and is 10 degrees away from the equator The Maunder Minimum was a period of time 1645 1715 when there were no sunspots and this made the Earth very cold What is solar magnetism Solar magnetism is when the magnetic field is 1 000 to 5 000 times stronger than in surrounding areas creating a sunspot How long is a sunspot cycle A sunspot cycle is the number of spots that changes roughly over 11 years Lecture 6 February 10 The Sun and Stars Where are active regions on the Sun Active regions on the Sun are in the photosphere surrounding a sunspot group What are prominences Prominences are loops or sheet like structures of glowing gas ejected from an active region of the photosphere What are solar filaments Solar Filaments are prominences viewed from a different perspective so it s against the Sun instead of space Particles take 3 4 minutes to come to Earth while light takes 8 minutes What does the Sun consist of The core consists of gamma rays the photosphere of visible light the chromosphere of UV rays and the corona of X Rays Except for the core all of these give off visible light What is the stellar spectra Stellar spectra differences are only due to different temperature stars that are classified into the following categories O B A F G K M L T O stars are the hottest stars while B T temperature decreases L and T stars are new …