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xarqi, Generalist
Category: Homework
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# Astronomy

The cygnus loop is now 2.6 degrees in diameter and lies 500 pc distance. (1 degree = 3600 seconds of arc) Find the linear diameter. I found this to be 10.91

But the second part of the question is If it is 50,000 years old what is the average velocity of expansion.
Could you help me with this part - thanks!
Divide the linear dimension by 50,000 to obtain the average
Customer: replied 11 years ago.
Reply to xarqi's Post: I need the answer in KM/S - not sure how to convert that
Easy enough - I'll do that now. BTW, I calculated the width to be
11.34 pc. What was your method?
Customer: replied 11 years ago.
Reply to xarqi's Post: I used the angular diameter converting the 2.6 degrees to 9000 seconds of arc I did 9000*500/206265 and got 21.82 for linear diameter - then got 10.91 for the radius.

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xarqi, Generalist
Category: Homework
Satisfied Customers: 596
Experience:
I'm not sure where the 206265 came from.

I used trigonometry. The diameter is 2 x 250 x tan(2.6°/2) =
11.346 pc
Customer: replied 11 years ago.
Reply to xarqi's Post: 206265 is a parsec in Astronomical units
Hey - I've made a mistake here! Sorry - let me fix it up
OK - I haven't had my coffee yet!

First - the linear diameter:
That is 2 x 500 x tan(2.6°/2) = 22.69 parsec.

That is 22.69 x 3.0857 x 10^16 m = 7.0024 x 10^14 km
Time is as above: 1.578 x 10^12 s

Velocity is 7.0024 x 10^14 km / 1.578 x 10^12 s = 443.75 km/
s

My profuse apologies!
And still another mistake!
We have to divide that by 2 for the radial velocity.
443.75/2 = 221.88 km/s

What a catastrophe!

Want me to arrange for a refund?
Customer: replied 11 years ago.
Reply to xarqi's Post: No I don't want you to arrange a refund because I kept getting 218 for an answer and as long as I'm in the ball park I'm ok with that - also you gave me some new strategies and I learned alot from your mistakes - thank you very much - this is a hard class and I have had major help from Just Answer - have a great night and smile!
You're too kind.

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