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Download Hertzsprung-Russell (H-R) Diagram Hertzsprung-Russell Diagram March 16 −
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Hertzsprung-Russell (H-R) Diagram Hertzsprung-Russell Diagram−March 16 • • • • More like test questions • Do you understand…? • Fewer leading questions • Do you understand? Reading HertzsprungRussell Diagram Main sequence is a mass sequence Lifetime of stars Do you understand? HR Diagram of star cluster 1. Stars: A-Aldebaran; B-Barnard’s Star; CCapella; D-Rigel What do you need to know about stars to answer the next 4 questions? Pick one 104 correct ans. a. b. c. d. e. • Public viewing sessions at MSU campus observatory. 2. 3. 4. 5. • Fri & Sat, 9-11pm, if it is not cloudy. • Mar 18 & 19 • Apr 15 & 16 • May 13 & 14 • 24-inch telescope in dome • small telescopes outside Hot-plate model of star Model of the solar interior How to read H-R Diagram Spectrum of black body Energy generation in the sun Which is the hottest star? Which is the smallest star? Which is the biggest star? If stars A-D replaced the sun, would people be able to live in Michigan? a. b. c. d. e. Luminosity (Lsun) è • • Try new format for some clicker questions 1 10-4 YNNN NYNN NNYN NNNY NNNN O B A F G Spectral class 25,000 10,000 6000 ç Temperature (K) K M 3000 [see Fig. 11.10] Hertzsprung-Russell (H-R) Diagram a. b. c. d. e. 2. 3. 4. 5. Hot-plate model of star: L=R2T4 Model of the solar interior X How to read H-R Diagram Spectrum of black body: Hotter=>bluer Energy generation in the sun X Which is the hottest star? Which is the smallest star? Which is the biggest star? If stars A-D replaced the sun, would people be able to live in Michigan? a. b. c. d. e. YNNN NYNN NNYN NNNY NNNN • Blackbody curve 1 Emitted energy per unit surface area è 1. Two Ways: • Compare amount of light in two colors Stars: A-Aldebaran; B-Barnard’s Star; C-Capella; D-Rigel What do you need to know about stars to answer the next 4 questions? Pick 104 one correct ans. Luminosity (Lsun) è • Taking a star’s temperature [Fig. 5.10] 5000o 4000o 3000o Wavelength è ç Energy • Spectroscopy Sodium 10-4 Hydrogen O B A F G Spectral class 25,000 10,000 6000 ç Temperature (K) K M Calcium Mercury 3000 Neon Wavelength è [see Fig. 11.10] 1 Annie Jump Cannon: Classify stars by their spectra G AJC K • Prof. Pickering’s Team in 1913, from Barbara L. Welther, 1982, Isis 73, 94. • AJC Flux à O B A F • BA, Wellesley, 1884 • Pickering’s assistant, 1896 • Henry Draper catalog of stars, 1918-1924 • Astronomer 1938 M G Wavelength à Very efficient: Draper catalog has 250,000 stars AJC 1863-1941 The TheH-R H-RDiagram Diagramwith withSizes sizes Stellar spectral types Type 106 Temperature >30,000 B 10,000-30,000 A 7500-10,000 104 F 6000-7500 → O G 5000-6000 K 3500-5000 M <3500 Luminosity • A Temperature Sequence 102 100 in K 10-2 Extra-Credit for best OBAFGKM mnemonic. • 3 clicker points for entering. • 3 clicker points for 10 best answers that can be repeated in class. • Enter in Angel before TestTable 3. [see 11.1] 10-4 25,000 10,000 5,000 Temperature 3,000 2 The H-R Diagram with schematic sizes Mass determines location on main sequence 106 106 High mass → 104 102 Luminosity Luminosity → 104 100 10-2 [Fig. 11.10] 10-4 102 100 10-2 Low mass 10-4 25,000 10,000 5,000 Temperature 3,000 25,000 10,000 5,000 Temperature 3,000 3