GIZMOS Student Exploration: Star Spectra / Star Spectra GIZMOS questions and answers_ Fall 2021/2022 (Solved)

Date: Student Exploration: Star Spectra Directions: Follow the instructions to go through the simulation. Respond to the questions and prompts in the orange boxes. Vocabulary: absorption spectrum, binary star, blueshift, Cepheid variable, emission spectrum, giant star, nebula, redshift, spectrum, star Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. What happens when light goes through a prism? The separation of visible light into its different colors is known as dispersion. This band of colors is called a 2. A rainbow is an example of a spectrum. What is the sequence of colors in a rainbow? You may abbreviate. Gizmo Warm-up The interior of a star produces a continuous spectrum of light, like a rainbow. Cooler gases in the outer layers of the star absorb certain wavelengths of light, causing dark lines to appear in the spectrum. The resulting absorption spectrum can tell astronomers a great deal about the star. 1. On the Star Spectra Gizmo, turn on Show labels. Select star 1 to see its absorption spectrum. How many lines do you see in the spectrum? 2. Drag the Hydrogen spectrum next to the Star spectrum so that the edges line up. Do some of the lines on 3. Drag the Helium spectrum next to the Star spectrum. Do some lines match? 4. Try out the other available spectra. Do any others have lines that match? , 5. Which elements have contributed to the spectrum of star 1? Note: The elements in a star’s spectrum do not necessarily reflect what the star is made of. The absorption spectrum is mostly determined by the surface temperature of the star. Activity A: OnLvl & PreAP Classifying stars Get the Gizmo ready: ● Check that Show labels are ON and Neutral spectra is selected. Question: How are stars classified? Introduction: Late in the 19th century, Harvard astronomer Edward Pickering wanted to sort and catalog the thousands of star spectra that had been collected by the Harvard Observatory. He hired several women to do the work, paying them 25 cents a day. The most prominent of these women was Annie Jump Cannon, who devised a classification system still used today. Harvard Classification Scheme Class Color Prominent spectral lines Surface Temp. (K) O Blue- Ionized helium, hydrogen > 25,000 B Blue-white- Neutral helium, hydrogen 11,000 – 25,000 A White Hydrogen, ionized sodium, ionized calcium 7,500 – 11,000 F White Hydrogen, ionized sodium and calcium; neutral sodium and calcium 6,000 – 7,500 G Yellow- Neutral sodium and calcium, ionized calcium, ionized iron, ionized magnesium 5,000 – 6,000 K Orange- Neutral calcium, neutral iron, neutral magnesium 3,500 – 5,000 M Red- Neutral iron, neutral magnesium, and neutral titanium oxide (not shown) < 3,500 1. Classify: Use the Gizmo to find the elements that are present in the spectra of stars 1 through 4. Remember to check both the Neutral spectra and the Ionic spectra. Then use the table above to classify each star and describe its surface temperature. (Note: A star spectrum may not display lines of all of the elements typical of its spectral class.) Star Color Elements in spectrum Class Surface Temperature (K) 1 2 3 4 2. On your own: Look up Annie Jump Cannon on the Internet or in a library and read her story. (You don’t have to type anything in the box) Activity B: Onlvl & PreAP Unusual stars Get the Gizmo ready: ● Select star 5. Question: What else can we learn from stellar spectra? 1. Observe: Observe the spectra of stars 5 – 10. Identify the elements in each spectrum, and try to classify each star. Describe any unusual features in these spectra you may encounter. Star Color Elements in spectrum Class Unusual features Match: Write the number of the star or object that matches each description. Then use this information to help identify the elements and reclassify the stars in the table above. Classify only stars 5 - 10.