Astrophysics (3 Viewers)

[fush]

yea i out sirius but looking back on it i can see why it is rigel, because u ahd to do stupid colour index arrghh i forgot, i just took the blue value

 

[boz]

For d)iii) i did this

Let I= k(pi)r^2

Now 100= k(pi)r^2 (1)

and 99= k(pi)( r^2-R^2) where r is radius of big and R is radius of small, as this is the apparent surface area.

so 99= k(pi)r^2 - k(pi)R^2
99= 100 - k(pi)R^2 from above
1= k(pi)R^2 (2)

100= r^2 / R^2 (1) / (2)
R= r/10

 

[boz]

what did you guys get for d)ii) though. I was stumped coz it sais the seperation between the two, does that mean you times the radius to center of mass by two?

 

[ramanij]

but color index is given by b-v and we are not give visual magnitude

 

[boz]

for q b i didnt do that colour index thing, i used the M=m - 5log(d/10) equation to work out the distance with the red filter, then i used the same formula for the blue filter and distance to work out the absolute blue magnitude.

I got rigel

 

[scnertho]

yea i did b-v aswell, i thought it may have been wrong, but i couldnt work out how simply reading the lowest value off the table could be worth 3 marks...

 

[superbird]

hopefully our module would get scaled higher compared to the others. some of the questions were really weird :s

 

[Muzzy]

what was the distance to rigel. i had 236.6 parsecs

thats what i got matey

 

[Muzzy]

Astrogets a moderate scale...............quanta to qwark and medical get bigger ones

 

[Gesus]

I agree, the section was pretty gay, but i loved the 7 marker
The biggest problem at my school was whether the radius meant orbital radius or radius of the star.....so that led some people getting a 1:1 ratio, but I worked on the radius of the stars and got R(dwarf) = (10-sqrt(99))/10 * R(star)
which is approx 1/200.

 

[Heinz]

I got 1/10 for that last one. Guess well see what happens. No more physics for a very long time! Wooohooo

 

[A2RAYA]

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.

i guessed cos i forgot to study that completely...i said that cos theyre in the negative index then it has to be rigel and looks like i was right

 

[Komaticom]

Sun's post MS life

What was the answer to the question about the reactions and life of the Sun after the Main Sequence stage?

I'm probably wrong, but I wrote helium to oxygen fusion in the core and supernovae. I heard something, a fews ago, about the Sun exploding in a many million (billion?) years. But that was years ago.

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Is the bluest star the one with the lowest blue filter value?

 

[superbird]

What was the answer to the question about the reactions and life of the Sun after the Main Sequence stage?

I'm probably wrong, but I wrote helium to oxygen fusion in the core and supernovae. I heard something, a fews ago, about the Sun exploding in a many million (billion?) years. But that was years ago.

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Is the bluest star the one with the lowest blue filter value?

after the main sequence stage the sun will turn into a red giant. this will signal the start of helium fusion.

 

[konggo]

Pft!!! Y are u people still taking about PHYSICs its over you may never ever do it agian...enjoy the sunshine enjoy...folic in the grass for all i care...just no more phsyics

 

[A2RAYA]

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

i just rearranged the one they gave us..the I proportional to pi R^2 one
no wonder i got 1:6 or 1/6 as my answer and noone else did