Unit 2 Stars and Galaxies Stars and Their Characteristics Life Cycle of Stars Galaxies and the Universe

Stars and Their Characteristics Unit 2 Stars and Galaxies CHAPTER HOME Stars and Their Characteristics Hydrogen and helium are the two most abundant elements in stars. 94% of the atoms in our sun are hydrogen, 5.9% are helium and only 0.1% are elements other than hydrogen and helium. So it will be a long time before our sun runs out of fuel.

Stars and Their Characteristics Unit 2 Stars and Galaxies CHAPTER HOME Stars and Their Characteristics Stars differ in mass, size, and surface temperature. Surface temperature affects the color of stars. Apparent magnitude, luminosity, and absolute magnitude are used to describe the brightness of stars. Betelgeuse Rigel There are stars of different brightness in the constellation Orion, including two of the brightest stars as viewed from Earth—Betelgeuse and Rigel.

Unit 2 Stars and Galaxies Apparent magnitude CHAPTER HOME Apparent magnitude The measure of how bright a star appears to be to an observer on Earth. Very big stars that are very far away can appear dimmer than closer stars. Which star in this photo seems the brightest?

Unit 2 Stars and Galaxies Luminosity The brightness of a star. CHAPTER HOME Luminosity The brightness of a star. The Luminosity of a star depends on BOTH its temperature and surface area. A hotter star is more luminous than a cooler one of the same radius. A bigger star is more luminous than a smaller one of the same temperature. Red giant stars is more luminous than the Sun because, even though cooler, they are much larger than the Sun.

Unit 2 Stars and Galaxies Absolute magnitude CHAPTER HOME Absolute magnitude The measure of how bright a star would be if it were located 10 parsecs from Earth. Your text book says 32 light years but it is really 32.58 light years. Which one has a greater magnitude, our sun or this brown dwarf star?

Stars and Their Characteristics Unit 2 Stars and Galaxies CHAPTER HOME Stars and Their Characteristics Stars that show variation in brightness are known as variable stars. There are a few different reasons for variation. One of them is called a cataclysmic variable. It means one star is consuming the other.

Stars and Their Characteristics Unit 2 Stars and Galaxies CHAPTER HOME Stars and Their Characteristics Stars can be grouped into constellations. In the past constellations were important for navigation and history. HERCULES BOÖTES COMA BERENICES CYGNUS CEPHUS LACERTA CASSIOPEIA CANES VENATICI LEO LEO MINOR URSA MAJOR URSA MINOR LYNX DRACO PERSEUS PEGASUS PISCES LYRA CAMELOPARDALIS

Unit 2 Stars and Galaxies Constellation CHAPTER HOME Constellation A group of stars that appear to form a pattern in the sky. This one is called the big dipper and points the way to the north star.

Unit 2 Stars and Galaxies Constellation CHAPTER HOME Constellation The constellations play an important role in modern astronomy. They bring order to the sky by dividing it into smaller segments, providing a base for naming celestial objects. This one is called Orion the hunter.

Stars and Their Characteristics Unit 2 Stars and Galaxies CHAPTER HOME Stars and Their Characteristics Distances in space are measured in astronomical units, light-years, and parsecs.

Unit 2 Astronomical unit Stars and Galaxies CHAPTER HOME Astronomical unit The average distance between Earth and the sun, about 150 million kilometers. The Earth is 1.00 ± 0.02 AU from the Sun. The Moon is 0.0026 ± 0.0001 AU from the Earth. Mars is 1.52 ± 0.14 AU from the Sun. Jupiter is 5.20 ± 0.05 AU from the Sun. Pluto is 39.5 ± 9.8 AU from the Sun. And yes I want you to copy this it is not in your book.

Unit 2 Stars and Galaxies Light-year CHAPTER HOME Light-year The distance that light travels in one year, about 9.5 trillion kilometers (5,878,630,000,000 miles). In the solar system we use astronomical units but the space between solar systems is so big we need to use light years or parsecs. At highway speeds of 55 miles per hour it would take you a little over 51,733,896 years to get there.

Unit 2 Stars and Galaxies Parsec CHAPTER HOME Parsec A unit of measurement used to describe distances between celestial objects, equal to 3.258 light-years.

Unit 2 Stars and Galaxies Review Questions CHAPTER HOME Review Questions What are the major elements in all stars? What is the difference between absolute magnitude and apparent magnitude? Which is the biggest: light year, parsec, astronomical unit? What is a constellation? hydrogen and helium. Apparent magnitude is how bright it looks to us, absolute magnitude is how bright it really is. A parsec. A group of stars.

Unit 2 Stars and Galaxies Time for a change  Word pair exercise CHAPTER HOME Time for a change  Word pair exercise It is time to work on your vocabulary. Today you are going to use the words from this unit to create meaningful sentences. The words from hand out one have numbers on them. Use the words that have the same number in a sentence that is not the definition. If you don’t finish in class finish the work for homework.

<Main Sequence> Unit 2 Stars and Galaxies CHAPTER HOME Life Cycles of Stars The Hertzsprung-Russell diagram plots a star’s luminosity against its surface temperature. The diagram’s groups of stars represent life-cycle stages of stars. Most stars are main-sequence stars. Hertzsprung-Russell diagram Temperature Luminosity Hottest Coolest Highest Lowest Blue Supergiants Red Supergiants Red Giants Red Dwarfs White Dwarfs <Main Sequence>

Unit 2 Life Cycles of Stars Stars and Galaxies CHAPTER HOME Life Cycles of Stars A star’s fate depends on its mass. A star with a mass similar to the sun’s will become a white dwarf. Stars with a Mass Similar to the Sun Stars with a Mass Much Greater than the Sun Nebula Protostars Sun-like star Massive star Red giant Red supergiant Planetary nebula White dwarf Black hole Neutron star Supernova

Unit 2 Life Cycles of Stars Stars and Galaxies CHAPTER HOME Life Cycles of Stars A star with a mass eight or more times greater than the sun’s will either become a black hole or a neutron star. Stars with a Mass Similar to the Sun Stars with a Mass Much Greater than the Sun Nebula Protostars Sun-like star Massive star Red giant Red supergiant Planetary nebula White dwarf Black hole Neutron star Supernova

Unit 2 Stars and Galaxies Nebula CHAPTER HOME Nebula A large cloud of gas and dust in space. If gravity pulls it together it will make a new star.

Unit 2 Stars and Galaxies Protostar CHAPTER HOME Protostar As a nebula shrinks it starts to spin and heat up forming a protostar. Protostars contract and heat up for millions of years eventually forming plasma when it reaches 10,000,000 degrees C. At this temperature nuclear fusion starts and it becomes a star.

<Main Sequence> Unit 2 Stars and Galaxies CHAPTER HOME Main sequence A star that is at the point in its life cycle in which it is actively fusing hydrogen nuclei into helium nuclei; also, the band of the Hertzsprung-Russell diagram depicting such stars. Hertzsprung-Russell diagram Temperature Luminosity Hottest Coolest Highest Lowest Blue Supergiants Red Supergiants Red Giants Red Dwarfs White Dwarfs <Main Sequence>

Unit 2 Stars and Galaxies Giant star CHAPTER HOME Giant star A large star with great luminosity and a diameter 10 to 100 times greater than that of the sun. When the star starts fusing helium into other elements it grows into a giant star.

Unit 2 Stars and Galaxies Super giants CHAPTER HOME Super giants The most luminous, most massive stars, with diameters greater than 100 times the diameter of the sun.

Unit 2 Stars and Galaxies Supernova CHAPTER HOME Supernova The brilliant burst of light that follows the collapse of the iron core of a massive star.

Unit 2 Stars and Galaxies Planetary nebula CHAPTER HOME Planetary nebula A halo of gases that is formed by the expelled layers of a star’s atmosphere. There is a white dwarf at the center of this. All the remains of a star that exploded.

Unit 2 Stars and Galaxies White dwarf CHAPTER HOME White dwarf The remnant of a giant star that has lost its outer atmosphere; the glowing stellar core. White dwarves eventually cool off and stop glowing.

Unit 2 Stars and Galaxies Neutron star CHAPTER HOME Neutron star The super dense remains of a massive star that collapsed with enough force to push all of its electrons into the nuclei they orbit, resulting in a mass of neutrons. The protons and electrons combine to form neutrons.

Unit 2 Stars and Galaxies Pulsar CHAPTER HOME Pulsar A distant neutron star that emits rapid pulses of light and radio waves instead of steady radiation. These remains of massive stars are not well understood.

Unit 2 Stars and Galaxies Black hole CHAPTER HOME Black hole The final life stage of an extremely massive star, with a gravitational field so intense that not even light can escape.

Unit 2 Stars and Galaxies Review Questions CHAPTER HOME Review Questions What is the first stage of a stars life cycle if the star is smaller than ours? What is the last stage of a star if the star is one hundred times bigger than ours? What is a star called when it is fusing hydrogen into helium in its core? All stars start as a nebula. A black hole. A main sequence star

Unit 2 It is time for your second lab activity. Stars and Galaxies CHAPTER HOME Time for a change  It is time for your second lab activity. This one is going to help you design better labs in the future. In groups of no more than 4 find all the problems with the labs designed on Unit 2 Lab Design Critique. Sorry nothing blows up in this one.

Galaxies and the Universe Unit 2 Stars and Galaxies CHAPTER HOME Galaxies and the Universe Galaxies contain millions or billions of stars. There are three major types of galaxies: spiral, elliptical, and irregular.

Galaxies and the Universe Unit 2 Stars and Galaxies CHAPTER HOME Galaxies and the Universe The Milky Way is the name of our galaxy. It has over 200 billion stars in it. The oldest known star found so far is 13 billion years old. It is a special type of spiral galaxy called a barred spiral galaxy.

Galaxies and the Universe Unit 2 Stars and Galaxies CHAPTER HOME Galaxies and the Universe Elliptical Galaxies have very few young stars in them. Most of the nebula have already become low mass stars like our sun. Elliptical Galaxy

Galaxies and the Universe Unit 2 Stars and Galaxies CHAPTER HOME Galaxies and the Universe Some galaxies do not have a regular shape, like a spiral or an elliptical galaxy. Most irregular galaxies were once spiral or elliptical galaxies but were deformed by gravitational action. Irregular galaxies also contain abundant amounts of gas and dust. Irregular Galaxy

Galaxies and the Universe Unit 2 Stars and Galaxies CHAPTER HOME Galaxies and the Universe Normal galaxies emit as much radiation as that given off by their stars. Active galaxies emit much more radiation than that given off by their stars, possibly due to super massive black holes at their center.

Unit 2 Stars and Galaxies Galaxy CHAPTER HOME Galaxy A group of millions, or even billions, of stars held together by gravity. The Hubble Space Telescope site estimates there are hundreds of billions of galaxies in the universe.

Unit 2 Stars and Galaxies Quasar CHAPTER HOME Quasar A very distant, extremely luminous celestial object that scientists consider to be a type of active galactic nuclei. This means they have huge black holes at the center of their structure. Quasars are thought to be some of the oldest bodies in the universe.

The Electromagnetic Spectrum EXIT The Electromagnetic Spectrum Radio waves Microwaves Infrared Ultra- violet X-rays Gamma rays Visible light Longer Shorter Wavelength (meters) 10-14 10-12 10-10 10-8 10-6 10-4 10-2 1 102 104 We can only see this little part of the electromagnetic spectrum

Unit 2 Stars and Galaxies Review Questions CHAPTER HOME Review Questions What are the three major types of galaxies? What is the name of our galaxy? How many stars are estimated to be in our galaxy? What is the difference between and active galaxy and a normal galaxy? Spiral, elliptical and irregular The Milky way. Over two hundred billion stars. Active galaxies produce more radiation than normal galaxies.

Critical thinking exercise Today you will be answering several open ended questions based on this unit. Use proper sentence structure. Use the terms that relate to the subject. Make sure you actually answer the question.

Any questions on Unit two? Then it is quiz time. You may use your notebook for this quiz. You do not have to use your notebook if you do not have it. You may not use anyone else’s notebook, your textbook, your phone or any other support devices. Good luck