* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Unit 3 - Section 9.2 2011 Star Characteristics0
International Ultraviolet Explorer wikipedia , lookup
Dialogue Concerning the Two Chief World Systems wikipedia , lookup
Aries (constellation) wikipedia , lookup
Observational astronomy wikipedia , lookup
Auriga (constellation) wikipedia , lookup
Planetary habitability wikipedia , lookup
Cassiopeia (constellation) wikipedia , lookup
Corona Borealis wikipedia , lookup
Type II supernova wikipedia , lookup
Canis Minor wikipedia , lookup
Star of Bethlehem wikipedia , lookup
Stellar kinematics wikipedia , lookup
Dyson sphere wikipedia , lookup
Malmquist bias wikipedia , lookup
Corona Australis wikipedia , lookup
Cygnus (constellation) wikipedia , lookup
Canis Major wikipedia , lookup
Stellar evolution wikipedia , lookup
Perseus (constellation) wikipedia , lookup
Star formation wikipedia , lookup
Timeline of astronomy wikipedia , lookup
Grade 9 Academic Science – Unit 3 Space Characteristics of Stars Section 9.2 Pages 370-373 All stars twinkle. After that, there are many visible differences such as colour and brightness, as well as measurable differences including temperature, mass and elemental composition. Star Characteristics Characteristic “Sub-Characteristics” Star Brightness Description Luminosity Total amount of energy produced by a star per second Measured by comparing it to the luminosity of the Sun set at 1. Sirius has a luminosity of 22 meaning it gives off 22X more energy per second than the Sun Distance Apparent Magnitude Luminosity is stronger if an object is closer. Why? The light is more concentrated when an object is close. Thus, the object appears brighter. Closer stars will appear brighter Brightness of star in the night sky as they appear from Earth The scale goes from bright (1) to faint (6). A low value of Apparent Magnitude means the star is close to Earth, while a high value means the star is far away. Absolute Magnitude Brightness of star in the night sky as if they were 33 ly away from Earth. Why? It allows us to differentiate between low-energy emitting stars and high-energy emitting stars over varying distances As above, the LOW value means a brighter star. See Table 1 on Page 371 to compare Apparent Magnitude with Absolute Magnitude Star Colour and Temperature Colour measures a star’s surface temperature. Blue is relatively hot Red is relatively cool Yellow is a mid-range temperature. Our Sun is 6,000OC and appears yellowish-white See Table 2 on Page 372 to compare star colours and surface temperatures. Elemental Composition Composition is determined by looking at the light emitted by the star. Each element has a unique number and configuration of electrons. These features means an element produces only certain wavelengths of colour. Thus, the light energy emitted by the star has its own unique spectral pattern. A SPECTROGRAPH is used to determine a star’s composition. A star’s spectral pattern is compared to the known spectra of the elements. If commonalities are detected between patterns, the star must contain that element. For practice with spectral patterns, see the activity below using Figure 1. Solar Mass Solar Mass is a value used to describe the masses of galaxies and stars OTHER THAN our Sun. Our Sun’s mass is 2 X 1030 kg. Other star masses are compared to the mass of our Sun. NOTE: Mass does not always reflect size (e.g., Large mass does not necessarily mean large sized star) Long-Distance Chemistry Analyzing Spectral Patterns to Identify Star Composition How do you know the chemical composition of a star? Each element has its own unique spectral pattern. Why? Each element has its own unique number AND arrangement of electrons. Methods 1. The figure displays the spectral patterns for five elements. What do the patterns tell you? 2. There is also a spectral pattern for the Sun. What is the elemental composition of the Sun? 3. There are three “mystery stars.” Using a ruler, line up the spectral patterns of the elements to the mystery stars. 4. Answer the following questions. a. In which two mystery stars is calcium present? b. Only one mystery star contains mercury (Hg). Which one? c. Which mystery star’s composition is LEAST like that of the Sun? d. In a brief paragraph, describe how a star’s elemental composition can be inferred by investigating its spectral pattern. To practice spectral analysis, go to the Exploring Earth website at http://www.classzone.com/books/earth_science/terc/content/investigations/es2803/es2803page02.cfm NOTE: You may have to install Shockwave to use this interactive demonstration Figure 1. Spectral Patterns for five elements, our Sun and three mystery stars Homework and Practice Page 373, Questions 1,2,5-7,9