Astrophysics (1 Viewer)

[bevstarrunner]

How was it..?
Personally, I found it quite reasonable...

What was (d)(iii)??

 

[Charon.]

i thought so too
i heard the answer to d) iii) was 1/10 or somthing like that from my teacher afterwards

 

[kris12345]

it wasnt too bad

i think i got 1/100 but astro is my worst topic so im probably wrong

 

[bevstarrunner]

I couldnt work out the right formula to use...I had that they were the same size or something...

 

[kris12345]

yeah i didnt use a formula i just assumed the the luminosity was 0 of the white dwarf there it only decreased the intentisty of the big star. and the big stars intensity was 100 and went down to 99 so i thought it must be 1/100th of the size i dont know if that is anywhere near write but

 

[Charon.]

i got about that (1/99) but im pretty sure im wrong

 

[Tredanse]

I got approx. 1/10.

Work out that the intenisty of the dwarf is 1 and the star is 99.

I rearranged some equations but damned if I can remember what they were.

I ended up with 0.1005.. or approx 1/10 the radius.

 

[bevstarrunner]

I still don't get it tho...i can see how u guys got your answers, but shouldnt the troughs be different magnitudes if one is bigger than the other...??

 

[kris12345]

nah the troughs are the same beacause the white dwarfs size is constant and therefore every time it passes in front of teh big star intensity dips by the same amount its etrinsic and periodic

 

[budj]

Yeh i got 1/10. What i did was that i said:
Let I(a) = intensity of white dwarf, I(b) = intensity of other star
Now I(a) = k(pi)r(a)^2, similarly for I(b)
And then dividing through I got {r(a)/r(b) = srt(I(a)/I(b))
Then you sub I(a) = 1, I(b) = 100, hence getting r(a)/r(b) = 1/10

 

[fush]

damn i got 1/100, i also fucked up the filter question prob only get like 2-3/6 for that part

 

[bevstarrunner]

nah the troughs are the same beacause the white dwarfs size is constant and therefore every time it passes in front of teh big star intensity dips by the same amount its etrinsic and periodic

yeah, but shouldnt there also be a trough when it goes behind..??

 

[budj]

Nah bevs, bcause the question says that assume that the white dwarf has neglegible luminosity, therefore as the white dwarf is masked by the other star, there is really no observable effect

 

[budj]

Also, I think that also related to the previous question in calculating the radius. Did all of you take the period as 6 days, therefore 6*24*60*60 seconds?

 

[bevstarrunner]

Nah bevs, bcause the question says that assume that the white dwarf has neglegible luminosity, therefore as the white dwarf is masked by the other star, there is really no observable effect

thx i kinda get it now...

 

[gerardk]

Hey what did yous get for b(i) ?? i said it was Rigel by CI = B - V ...but i thought that V was a yellow filter not red???

 

[smexy]

no i did it in years, 6/365 =.16 years
i ended up getting like one hundred and something kms apart

 

[smexy]

yea i put Rigel too, betelgeuise was 1.3, sirius was 0 and Rigel was -.04

 

[ramanij]

i put sirius coz the blueset star will appear dullest in red filter so using absolute magnitue column where all stars were taken as 10 parsecs away sirius had the highest magnitude hence the dullest hence the bluest.

 

[ramanij]

what was the distance to rigel. i had 236.6 parsecs