Star-bright 

In the article “Star Hopping-Bright Winter Stars” it states how during winter in the northern hemisphere there are several large, luminous stars.  These stars are more bright because the distance to our solar system is closer.  The three top stars in the constellation are Orion, Betelgeuse, Merissa, and Bellatrix.  They all have properties of Giant type and they dwarf the sun by either mass, diameter, or luminosity.  The article also states that stars show different colors because of their temperature.  Basically, all stars are extremely hot internally but the temperature gets cooler towards the outer layer.  Hotter stars appear yellow, still hotter stars appear white, and the most hottest appear blue.  Astronomers typically measure the stars energy flux, emitted power (per square meter of surface).  The equation reads as follows :

Where F stands for energy flux, Tis temperature and o is a constant number.

This article relates to the conceptual objective “I can explain how astronomers determine the luminosity, the temperature, and size of stars.” The article touches on how the different colors of stars determines the temperature.  Which is how astronomers examine their energy spectrum.  Therefore, they fit the mathematical spectrum by using Wien’s Law.  Luminosity was also discussed which is the total amount of energy that leaves a star per unit time.  Astronomers use the Stefan-Bolzman Law which states that the total radiant heat energy emitted from a surface is proportional to the fourth power of its absolute temperature.  Once Astronomers know the distance to a star, they can measure its brightness, and infer the luminosity.  Once that is figured out they measure its temperature from spectrum and hence get its size.

In the article I discussed how the stars appear different colors depending on the temperature.  This concept  is touched on in our textbook, “The Essential Cosmic Perspective.” The book states on page 117, “As [stars] gets hot, it begins to glow with visible light, and it glows more brightly as it gets hotter, demonstrating [Stefan-Boltzman law]. Its color demonstrates the [Wien’s law]. ” We also discussed luminosity in our tutorial workbook page 55 where it showed the concept of how luminosity increases based off the size and temperature.

This article and conceptual objective was very informative.  I have a greater understanding of luminosity.  I like how in this chapter of class, math is involved because math is my favorite subject so I like how they intertwine the two.  I thought it was interesting how the article states that the closer you get to a star internally the hotter it gets, I would of thought the opposite.  Overall, after reading this article and studying this conceptual objective I have a better understanding of how the stars in our universe work.





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