Understand the electromagnetic spectrum and how it is organized. Understand what different types of electromagnetic radiation can reveal about astronomical objects. Understand and describe important properties of electromagnetic radiation. Understand how technology is used to collect electromagnetic radiation and turn it into images. Understand what can be learned from analyzing the light from astronomical objects. Understand how different types of lenses and telescopes work Understand and describe the quantization of energy at the atomic level Understand that all objects emit and absorb electromagnetic radiation and distinguish between objects that are blackbody radiators and those that are Qualitatively describe the shift in frequency in sound or electromagnetic waves due to the relative motion of a source or a receiver

Read the FYI The color of stars Answer the 2 questions in your science journal.

Question of the day How can you determine the temperature of a star when they are so far away? You will need a calculator today

The Color of Stars Blackbody radiation is the type of EM radiation emitted by a blackbody (an opaque and non-reflective body) held at constant, uniform temperature. Ie. Temperature determines color, so you can look at color to figure out temperature. The temperature of a lava flow can be estimated by observing its color. The result agrees well with measured temperatures of lava flows at about 1000 to 1200 °C.

Wein’s Law Max λ = C_ T(K) C= constant = 0.29 cm K Mathematical formula that shows the relationship between temperature and color (wavelength) Max λ = C_ T(K) C= constant = 0.29 cm K T(K) = temperature in K λmax= maximum wavelength (color)

Calculate the wavelength. [Wein’s Law] Max λ = C_ T(K) Star with a temperature of 3,000K Star with a temperature of 15,000K Star with a temperature of 5,800K (for those that just want to sit there and let other students do this while they do nothing, just know that you will have to do this yourself on the test next week – you should practice) Determine the color cm to nm (multiply by 10 million) C=0.29 cm

Calculate the wavelength. [Wein’s Law] Max λ = C_ T(K) Star with a temperature of 3,000K = Star with a temperature of 15,000K = Star with a temperature of 5,800K = 9.67*10^-5 (967nm) 1.93*10^-5 (193nm) 500 nm

When looking at a distant star, you observe its spectrum When looking at a distant star, you observe its spectrum. You find that the peak wavelength for this star is at 480nm. What is its surface temperature? Max λ = C_ T(K)

480nm .0000480 = .29/T T = .29/.0000480 T = (÷10,000,000) = .29/T 6,041.7º K

Stefan-Boltzmann Law E = σT4 E=energy -- measured in W/m2 The total energy emitted (intensity) by an object is equal to a constant (σ) times the temperature of the object to the 4th power E = σT4 E=energy -- measured in W/m2 σ=constant =  5.67×10−8 T=temperature

Calculate. [Stefan-Boltzmann Law] Our sun has a surface temperature of 5,800K. If a star has a temperature of 11,600K approximately how many times more energy will it emit?

Calculate. [Stefan-Boltzmann Law] Our sun has a surface temperature of 5,800K. If a star has a temperature of 11,600K approximately how many times more energy will it emit? σ·11600^4 = σ·5800^4 18106393600000000 1131649600000000 =16

Calculate. [Stefan-Boltzmann Law] Our sun has a surface temperature of 5,800K. If a star has a temperature of 2,900K approximately how many times less energy will it emit?

Calculate. [Stefan-Boltzmann Law] Our sun has a surface temperature of 5,800K. If a star has a temperature of 2,900K approximately how many times less energy will it emit? 5800^4= 16 2900^4

Energy intensity (Watts/m2) Use Wein’s Law and Stephan-Boltzmans Law to complete a row of your chart. Peak color Temperature (K) Wavelength (nm) Energy intensity (Watts/m2) Infrared 4142 700 16,688,735.7 Red 700-635 Orange 635-590 Yellow 590-560 Green 560-490 Blue 490-450 Violet 450-400 Ultraviolet <400

Use the median value for each color Color wavelength interval infrared~ >700nm red~ 700–635 nm orange~ 635–590 nm yellow~ 590–560 nm green~ 560–490 nm blue~ 490–450 nm violet~ 450–400 nm Ultra-violet~ <400nm

infrared 700 nm 700nm = (.29 cm/K)/ T .00007 cm = .29/T T= .29/.00007 T ~ 4142 K C=0.29 cm

infrared T ~ 4142 K 5.67x10-8 x 41424 .0000000567 x 4142 x 4142 x 4142 x 4142 E = 16,688,735.7 Watts/m2

C= 0.29 cm Color wavelength interval infrared~ >700nm red~ 700–635 nm orange~ 635–590 nm yellow~ 590–560 nm green~ 560–490 nm blue~ 490–450 nm violet~ 450–400 nm Ultra-violet~ <400nm Use the median value for each color

Use Wein’s Law and Stephan-Boltzmans Law to complete a row of your chart. (pick a different one that the people around you) Peak color Temperature (K) Wavelength (nm) Energy intensity W/m2 Infrared 4142.8 700 16,702,554.23 Red 4344.5 667.5 20,200,865.19 Orange 4734.6 612.5 28,493,820.12 Yellow 5043.4 575 36,686,279.61 Green 5523.8 525 52,788,319.53 Blue 6170.2 470 82,183,308.09 Violet 6823.5 425 122,919,088.3 Ultraviolet 7250 400 156,651,690.2

Please answer the question of the day How can you determine the temperature of a star when they are so far away?

This is on Canvas. It is due SUNDAY @ midnight.