Error propagation of distance modulus and parallax

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Joined: Fri Jun 17, 2011 9:49 pm

Error propagation of distance modulus and parallax

Post by muse19 »


Here is my problem: there is a star, for which we know the distance, d=21.2 pc,
the measurement error is delta_d=1.8 pc. The question is that how far should we put this star,
so that the following equation would be true: d/delta_d = 3?
The teacher told me to use two formulas: m-M=-5+5log(d) and pi=1/d (pi=parallax),
and then do some error propagation calculations.
Of course, I have already tried it using the equations above,
but I did not succeed.
Does anybody have any idea?
Actually, it would be OK as well, if anybody could do it using
any other equations.
Thank you, and sorry for my english.

Cheers, Joe
Posts: 349
Joined: Fri Jul 06, 2007 9:51 pm

Post by big_kev »

Is it just me or is something missing from this question.
Posts: 6594
Joined: Sat Dec 11, 2004 8:18 pm
Location: Manchester

Post by Cliff »

Dear Big_Kev
No! I do not think it is necessarily you ?
One thing that seems to be a possible problem is that the teacher is incompetent, otherwise I would have suggested asking the teacher for advice.
Best wishes from Cliff
PS "think" added above 6th July
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