Quote:
Originally Posted by ngcles
Can you show the working for me??
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I do it from a complicated spreadsheet that I created for my double star work. I just plug in the parallax in mas (milliarcseconds) with the given errors, and it spits out the results.
However, the nuts and bolts of the calculations you require are as follows;
Distance is calculated as;
d (pc) = 1 / p x 1000
Where p = parallax (in milliarcseconds)
If the parallax is in arcsecs, it is just ;
d (pc) = 1/ p
To convert parsecs (pc.) to light years (ly) it is multiplied by 3.2616
(To convert light years (ly) to parsecs (pc.)it is multiplied by 0.30660)
To find the true separation (TS) of stars, in suitable units is a little more complicated. Easiest is to do;
TS = sin (Sep/3600) x d (in parsec)
The using the calculated true separation (TSep), then convert it into the units you want by;
TD (light-years) = TS x 3.2616
TD (AU) = TS x 63240
TD (km) = TS x 9460000000000 (ten zeros)
[or 9.46x10^12]
Where;
Sep = Separation (arcsec)
d = distance in parsecs
TS = True Separation
TD = True Distance
Note: Finding the sine (sin) of very small angles is subject to significant errors due to the smallness of the angle. I use another long-winded method of calculating to deduce this more exactly doing it electronically. However, in simple calculators I find for most uses it is ample if you are seeking values that are fairly close.