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Astrophysics - Discuss Questions! (1 Viewer)

habitres

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What did you guys think of the Astrophysics section?
Hard easy etc?
The life sequence of the star (flow diagram) was pretty easy.

In the last question (binary system)
I got:
Star B was white dwarf
Star A was main sequence
Also determined brightness ratio
Also determined distance (using distance modulus (but got 1pc for one and 17pc for the other)
Also determined combined mass of stars (using period)
 

gayforniall

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Yes I said it was an Eclipsing binary system as demonstrated by the light curve. I calculated the mass of the system and also the brightness ratio. I suggested the possibility for calculating the distance but did not actually calculate it. I stated that Star B was a White Dwarf and Star A was Main Sequence. I hope I do fine!

For the production of elements I wrote about neutron capture, particularly during supernovas.
 

lance687876

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im sorry, looking at stars is suck.

QUANTA TO QUAKEEEEEEEE! FTW
learn some english, weirdo.
the last question will definitely discriminate the band 5 and 6 students.
you had to work out that it was an eclipsing binary, which star was more luminous, the size, the intensity ratio, the combined mass, the period and use ALL of the given data.
saying what the stars are is not important. determining the distance is completely useless and a waste of time. it asked you about the SYSTEM.
l think the question was innacurate, it should've asked us what to find.
 

lance687876

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Yes I said it was an Eclipsing binary system as demonstrated by the light curve. I calculated the mass of the system and also the brightness ratio. I suggested the possibility for calculating the distance but did not actually calculate it. I stated that Star B was a White Dwarf and Star A was Main Sequence. I hope I do fine!

For the production of elements I wrote about neutron capture, particularly during supernovas.
didn't you have to talk about H fusion to He, and then the CNO cycle which makes heavier elements in supergiants?
 

habitres

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didn't you have to talk about H fusion to He, and then the CNO cycle which makes heavier elements in supergiants?
Thats what I did, and then talked about formation of elements in outer layers of supernova (higher mass than Fe)

I really hope I mentioned that it was an eclipsing binary system :|
 

markGee

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i was heapsss stressed for time when i got to the end of astrophysics (had to go back and do the transmission and tower questions) so for the last one i just found the mass of the system, the distance to the stars (but im pretty sure i got it wrong) and the brightness ration of each stars. soo hopefully i scape like a 3 out of 6 or something
apart from the last question im pretty sure i murdered the rest of it.. wrote like 2 pages on the synthesis of elements but i talked a lot of crap and my terminology sorta deteriorated cos i was rushing lol
 

someth1ng

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For the last question, I didn't do brightness ratio but I said:
Compared the magnitudes, luminosity and spectral class --> one must be significantly larger than the other.
Used H-R diagram to show that white dwarf vs main sequence
Eclipsing binary --> said they were a binary system due to sufficiently small separation --> which was primary minimum and which was secondary minimum --> the plane was on the observer's line of slight --> period of 40 years.
 

kiinto

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- I identified that it was an eclipsing binary, therefore plane of orbit was in line with line of sight.
- Identified Star A as the brighter of the two, which caused the large brightness dip when it was eclipsed by the smaller star.
- I calculated the mass of the system
- Identified the star types of either by plotting on the H-R diagram (Main Sequence and White Dwarf)
- I extrapolated the approximate positions on the H-R diagram to identify approximate values for Absolute Magnitude, which I said were very close to the observed Apparent Magnitudes.
- From the above I determined the distance to the system to be around 10pc.

Astro was relatively easy
 

cheepy5

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What did you guys think of the Astrophysics section?
Hard easy etc?
The life sequence of the star (flow diagram) was pretty easy.

In the last question (binary system)
I got:
Star B was white dwarf
Star A was main sequence
Also determined brightness ratio
Also determined distance (using distance modulus (but got 1pc for one and 17pc for the other)
Also determined combined mass of stars (using period)
Yeah i did the same as you!
I much preferred this type of question last rather than a 7-8 mark analysis of measurement techinques or something else from astro.
Overall the questions were pretty straight forward except i got stumped on the 1st question for a while, do astronomers use both M and m so they can determine distance to the star.
 

habitres

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Yeah i did the same as you!
I much preferred this type of question last rather than a 7-8 mark analysis of measurement techinques or something else from astro.
Overall the questions were pretty straight forward except i got stumped on the 1st question for a while, do astronomers use both M and m so they can determine distance to the star.
Yes, the absolute and apparent magnitude is necessary for calculating distances via the modulus equation.
 

NickGero

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Did people talk about spectographs/ light meters etc for the spectroscopy/ photometry question?
 

NickGero

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I did spectrograph and photoelectric/photographic methods.
Yeah I realised after I should've done photoelectric/ photographic methods :/

Do you think talking more about the visual techniques could've worked as well, e.g. light meters, obtaining colour index etc. :/
 

someth1ng

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Yeah I realised after I should've done photoelectric/ photographic methods :/

Do you think talking more about the visual techniques could've worked as well, e.g. light meters, obtaining colour index etc. :/
Photometry is specific to determining brightness, a photometer can work but obtaining colour index might not be so relevant.
 

kiinto

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Yeah I realised after I should've done photoelectric/ photographic methods :/

Do you think talking more about the visual techniques could've worked as well, e.g. light meters, obtaining colour index etc. :/
It depends. It was worth four marks. So they'll probably be looking for the device used for each, including brief mention to how they work (2mks). And then the information each is used to collect (1mk). And what that information is used to do (1mk). So, if you didn't mention photoelectric/photographic technologies (which is how a Photometer works) you might drop a mark.

Edit: So colour index is relevant, but it won't make up for a lack of the photographic/photoelectric. That's my guess.

Edit 2: But a light meter is pretty much mentioning the photoelectric effect/photographic plate, so you might not lose a mark. But if they need to get a good spread, you will.
 
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