Activity+7+Life+Cycles+of+Stars

=**Activity 7 Our Community's Place Among the Stars pg E69**= - Sam Sanneman
 * -Clara B**

Think About It 1 __As your stargaze, what do you notice about the stars?__ __When I stargaze (which really isnt that often) I noticed that the position of the stars move. And then we learned that stars orbit and change positions everyday. Just like how the Earth moves around the Sun. I also noticed that some stars are alot more easily seen than others because its brighter. So that got me thinking, does it mean that that sun is closer to us or its just a lot more bigger. But one thing is for sure, the Sun is the only star in out Solar System. All the ones we see are from other galaxies far far away. -Diana Kangaroooooooooo-__ Think About It #2 __Do some stars appear brighter than others? Larger or smaller?__ __As you look into the night sky, you see thousands of stars twinkling against the black night sky. If you look closely at them you realize that they are differnt. Some are small in comparison to the stars around it; some are brighter too. This could be because of the distance from the star to Earth, the larger, brighter stars are going to be the ones closer to Earth. -Theresa Duncan__

__INVESTIGATION__ __Part B__ __1. A) The vertical axis on the graph represents the luminosity of the stars that are plotted.__ __B)The horizontal axis on the graph represents the surface temperature of the stars that are plotted.__ __C) The yellow dot, the sun, has a luminosity of 1 and a surface temperature of about 6,000 K.__ __D) The hot and bright stars would be in the top left hand corner of the graph, the hot and dim stars would be in the lower left hand corner, the cool and dim stars would be in the lower right hand corner, and the cool and bright stars would be in the top right hand corner of the graph. This is also illustrated on the graph.__ __-emily soupal__

Digging Deeper Notes__

1. What is the relationship between a stars temperature and its brightness?

Generally speaking, the hotter the star, the brighter it shines. However scientifically speaking: .- Amanda Medina
 * Main sequence stars have proprotional luminosity and brightness.
 * Red giants usually have high luminosity and low temperatures.
 * White dwarfs have low luminosity and high temperatures

2.) Which type of star (low-mass, medium, or high-mass), burns fuel quickly? Explain why it burns fuel quickly. 3.) Rank the three categories of stars in order of how long they are expected to live - Elizabeth Moreno
 * High mass stars burn fuel the fastest, because they have the more mass the star has, the faster it takes to burn.
 * Low mass stars - 20 billion years
 * Sunlike stars - 10 billion years
 * High mass stars - few tens of millions of years.

__Lives of Stars__
 * Our solar system is part of the milky way galaxy.
 * Our stellar neighborhood is about two-thirds of the way out on a spiral arm that stretches from the core of the galaxy.
 * Astronomers use a magnitude scale to describe the brightness of objects.
 * Luminosity- The total amount of energy radiated by an object every second.-Lauren Cowart
 * massive stars lose mass as they age, and at one point their cores collapse catastrophically.
 * supernova is a cataclysmic explosion, that is the end of a super giant's life.
 * a neutron star is a tiny remnant, left behind from when most of the star's mass is hurled out into space.
 * stellar black hole is a place where not even light can escape, because the gravity is so strong.
 * when the star is massive enough, the force of the explosion can get so strong that the remnant can be imploded into a stellar black hole.- Kelsey Lester

__Luminosity__
 * Astronomers use the term luminostity for the total rate at which a star emits radiation energy.
 * Unlike apparent brightness (how bright the star appears to be) luminosity is an intrinsic property. It doesnt depend on how far away the star is.
 * Hertzsprung and Russell found that the luminosity of a star was related to its surface temperature. -Alex Huston

__Classifying Stars__
 * Stars are organized by scientist that label them by the precise magintudes that describe the brightness of the stars.
 * The brightess star that we know of is called Sirius A and which the magintude of the star is -1.4 this is not including the Sun which is at -27.
 * For the naked eye the brightess star that we can see is at sixth magintude anything less we have to use a form of a telescope.
 * One of the most advance telescopes is the Hubble Telescope which can detect the magnitude of thirty. - Jennifer Tipton
 * Today scientists use a more precise system of magnitudes to describe brightness.- DanielNguon

__Mores on Lives of Stars__
 * Newborn stars are like baby chickens pecking their way out of a shell.
 * As these infant stars grow, they bathe the cloud surrounding them in strong ultraviolet radiation.
 * This vaporizes the cloud, creating beautiful sculpted shapes in the clouds.
 * Ultraviolet light carves out a shell of gas and dust around stellar newborn stars. -Alex Huston

__The Death of a Star__ __Geo Words__ __Check Your Understanding #1__ How do astronomers classify stars?
 * A star loses its mass in the form of a stellar wind throughout its entire life.
 * The Sun will end up forming a planetary nebulae in about five billion years.
 * Supergiant stars have their cores collapse violently when they die and that is called a supernova explosion.
 * A supernova explosion can either form a tiny neutron star or a stellar black hole.Dalton Goss
 * Luminosity- the total rate at which a star emits radiation energy.
 * Molecular cloud- a large and relatively dense cloud of cold gas and dust in interstellar space from which new stars are born.
 * Supernova- when the core of a supergiant collapses, a cataclysmic explosion occurs.
 * Neutron star- the imploded core of a massive star produced by a supernova explosion.
 * Stellar black hole- a place where the gravity is so strong that not even light can escape. -Trudy Morse
 * Astronomers classify stars using stellar classifications, which depend on the temperature and color of the stars. This also helps astronomers understand where a certain star is in its evolutionary history. Astronomers study stars with spectrographs to find out their temperature and chemical makeup to get the information they need in order to classify them. There are seven main categories of stars, O, B, A, F, G, K, and M, which are in order from highest temperature to lowest temperature (in kelvins). -Barbara V.

How do astronomers classify stars?
 * In the older days, scientists used to classify stars by the brightness only, simply putting them in order from magnitude 1 to 6. 1 being the brightest and 6 being the dimmest. Today scientests still use the same magnitude scale, but it has become much more precise and accurate because of newer telescopes and other technologies. The levels of magnitude are also much greaters since Hubble came out. It can detect stars up to the 30th magnitude. ->Tanner A.

__Check Your Understanding #2__ Write a brief summary outline of how stars are born.
 * Stars are bron by first the formation of dust and gas. Then clouds begin with clump and then heats up by gravitational attraction when the heat is 15 million kelvins then the star is formed.> Esmeralda O

__Check Your Understanding # 3__ Q: What determines the way a star dies? A: How a star dies depends on the amount of mass that the star contains. Thoughout a stars life it loses mass in the form of stellar wind. As a star gets older/ ages it loses more and more of its mass. A star as big as the sun will end its day as a tiny shrunken remnants of itself. --> Destini Jones

__Understanding and Applying What You Have Learned #3__ Q: What happens to the material left over from the death of a star? A: The material that is shed from dying stars makes its way into space between the stars. There it mixes and waits for a slow gravitational contraction down to a new episode of starbirth and ultimately star death. Because humans evolved on a planet that was born from a recycled cloud of stellar mass, they are very much star "stuff"-part of a long cycle of life, death, and rebirth. Emily Harvey

Kayla R-->whens stars are categorized they tend to stay there throughout the time. The sun is supposed to become a red giant star in about 10 million years.--Kayla R Digging Deeper Lives of stars continued -Courtney M
 * unlike apparent brightness luminosity is an intrinsic property
 * in the 1900s Ejnar Hertzsprung and Henry Norris Russell independently made the discovery that the luminosity of a star is realated to its surface temp.
 * the HR diagram does not tell you how the stars change
 * the life cycle of a star begins with the molecular cloud.

__**Stellar Black Holes**__ When a supergiant explodes the explosion is called a supernova. If the explosion is large enough the remnants implode into a stellar black hole. Gravity is extremely intense in black holes. The gravity is so intense that not even light can escape. hence the name black hole. Lots of small comets and asteroids are sucked into these black holes.



Neutron star- the imploded core of a massive star produced by a supernova explosion, a supernova which is a death explosion of a massive star whose core has completely burned out like a neutron star. supernova explosions can temporarily out shine a galaxy. --- kevin boe

__Molecular Cloud__ The life cycle of a star starts by what is called a molecular cloud. Basically its a large cold cloud that is mostly made up of molecular hydrogen and helium. There are some other gasses to like carbon monoxide. The gasses in the cloud clump togeather, mixing all around. Eventually the core begins to heat through friction, brining more material in. When the temperature in the center reaches 15 million kelvins,the stellar fusion begins to react and a star is born. -Lauren Cowart

Steller Classification Temperature (K)

O 25,000 K and higher B 11,000 - 25,000 K A 7,500 - 11,000 K F 6,000 - 7,500 K G 5,000 - 6000 K K 3,500 - 5000 K M less than 3,500 K


 * //__-BLAKE WEIL__//**