# Distance to stars

• 5 Replies
• 2483 Views
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#### Ezkerraldean

• 372
##### Distance to stars
« on: July 18, 2006, 05:01:15 AM »
Distance to stars

Measure intensity through observation

Intensity = luminosity/4πD2

Measure λmax through observation

Wien’s Law      λmax=b/T    (b=displacement constant = 2.897 7685 × 10–3 m K)

Calculate surface temperature of star

Stefan-Boltzmann law      luminosity = σT4 (σ= Stefan-Boltzmann constant = 5.670 4×10−8 W•m-2•K-4)

Therefore (re-arrange first equation) 4πD2 = luminosity / intensity
D=distance to star

try it. i doubt it comes up with 3000 miles.
tf?

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#### Ezkerraldean

• 372
##### Distance to stars
« Reply #1 on: July 18, 2006, 06:00:04 AM »
and a slightly easier way to do it at home:
http://www.exploratorium.edu/snacks/solar_brightness/index.html

"The distance to the sun is 1.5 x 10^11 m."
tf?

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#### Erasmus

• The Elder Ones
• 4242
##### Distance to stars
« Reply #2 on: July 18, 2006, 09:31:01 AM »
Neat ... but how can we trust the constants b and σ or the laws themselves?
Why did the chicken cross the Möbius strip?

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#### Ezkerraldean

• 372
##### Distance to stars
« Reply #3 on: July 18, 2006, 09:35:30 AM »
well, Wien's Law works just fine with lightbulbs.
tf?

#### Meleecow

• 8
##### Distance to stars
« Reply #4 on: July 18, 2006, 09:37:58 AM »
but star's are a big bigger then lightbulbs, and wouldnt the consistancy and size of the object, and that fact that its burning something completely different then anything here on earth dismay the results a bit?

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#### Ezkerraldean

• 372
##### Distance to stars
« Reply #5 on: July 18, 2006, 09:40:35 AM »
Quote from: "Meleecow"
but star's are a big bigger then lightbulbs, and wouldnt the consistancy and size of the object, and that fact that its burning something completely different then anything here on earth dismay the results a bit?

look at the fucking law, for fucks sake. it involves the median emitted wavelength and temperature. not mass or size or anything else.
tf?