Lydia Baker - Spectral Lines Gizmo Digital

Activity A: Classifying stars Get the Gizmo ready : ● Check that Show labels is on and Neutral spectra is selected. Question: How are stars classified? Introduction: Late in the 19 th 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 Blue Hydrogen and Helium O > 25,000 2 Orange Calcium, Iron and Magnesium K 3,500 - 5,000 3 Blue Hydrogen and Helium O > 25,000 4 White Hydrogen, sodium and calcium A 7,500 - 11,000