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Re: Astronomy C

Posted: March 5th, 2017, 4:19 pm
by Adi1008
Here's my Astronomy test from the recent Katy Regional Tournament, held at Beckendorff Junior High (key). If you have any questions about it, feel free to PM or email me!
Are there any rules or regulations for high schoolers to be event supervisors? Or do you just apply / ask like anybody else with an application?
The tournament was looking for someone to write an astronomy test and reached out to local science olympiad teams (e.g. Seven Lakes). As someone who likes both astronomy and writing tests, I volunteered to write the astronomy test.
Are there any rules or regulations for high schoolers to be event supervisors? Or do you just apply / ask like anybody else with an application?
I don't know how it is in Illinois (though likely mroe formal than in other areas) but many regionals are sufficiently short on event supervisors that they'll pretty much take any adult with a pulse, and any high schooler who's sufficiently competent. However, I've not heard of someone writing a regional test for their own division before.

Nice test btw Adi; I scored 26/37 on the first part, and 13/26 on the second part (I completely flipped 7a through 7d and lost 8 points there ugh). How does that compare?
In general, Texas has a shortage of event supervisors (but the event supervisors we have are pretty great and try their best!), so for small tournaments like this, students will help out. KRT specifically makes sure that all 23 national events are held which is fairly uncommon for Texas regionals (UT is another one that has all 23 events).

The top score was in the mid 20s out of a total of 63, so compared to them, you did well.
It's not unheard of to see high schoolers supervising B division with adult oversight at lower levels of competition, but I'd be leery of them doing their own division considering conflicts of interest, content area and assessment expertise, ES experience, or what have you. My guess would be that Adi wrote the test, passed it to a proctor, and didn't compete in the event at that tournament. If not, well...the world's a big place. :geek:
Your guess is correct; I only wrote the test and passed it on to an adult proctor. I had a conflict that day where I missed a few hours of the tournament when the event was taking place, so even if I wanted to actually administer the test, I wouldn't be able to.

Seven Lakes and Beckendorff don't compete in KRT, but rather, go to other regional tournaments (Seven Lakes went to TAMUG for Regionals, and Beckendorff is going to UT-Austin)

Re: Astronomy C

Posted: March 9th, 2017, 1:46 pm
by raxu
We've been trying the Princeton Invitational Astronomy test, and it has been near-impossible... Are questions about other stellar classification systems, fusion, eccentricity of systems, and somewhat-random facts normal on a State/National level test?

Re: Astronomy C

Posted: March 9th, 2017, 2:17 pm
by antoine_ego
We've been trying the Princeton Invitational Astronomy test, and it has been near-impossible... Are questions about other stellar classification systems, fusion, eccentricity of systems, and somewhat-random facts normal on a State/National level test?
I can't speak for State level tests because they typically vary a lot depending on the state. However, the Princeton test was a bit too difficult, especially since Calculus was required for some of the math questions. I wouldn't expect of anything as trivia-based as the Princeton test. That being said, you should know a great deal about classification systems, eccentricity, etc, because those could most certainly pop up on a Nationals test. If you want a good approximation of the Nationals test, look at the MIT invite test, since they were written by the same people.

Re: Astronomy C

Posted: March 9th, 2017, 2:43 pm
by Unome
We've been trying the Princeton Invitational Astronomy test, and it has been near-impossible... Are questions about other stellar classification systems, fusion, eccentricity of systems, and somewhat-random facts normal on a State/National level test?
I can't speak for State level tests because they typically vary a lot depending on the state. However, the Princeton test was a bit too difficult, especially since Calculus was required for some of the math questions. I wouldn't expect of anything as trivia-based as the Princeton test. That being said, you should know a great deal about classification systems, eccentricity, etc, because those could most certainly pop up on a Nationals test. If you want a good approximation of the Nationals test, look at the MIT invite test, since they were written by the same people.
Note, the Nationals test is generally significantly harder than the MIT test, though not as hard as the Princeton test. The Nationals test also uses obscure knowledge in application-based question, as opposed to how Princeton was more about spitting out obscure knowledge (most of which were directly from Wikipedia, so it shouldn't have been too hard if you had a laptop).

Re: Astronomy C

Posted: March 21st, 2017, 3:18 am
by antoine_ego
I wonder what the Nationals test will be like. Is it just me or is this topic a lot easier than last year in terms of math?

Re: Astronomy C

Posted: March 21st, 2017, 10:16 am
by Ashernoel
I wonder what the Nationals test will be like. Is it just me or is this topic a lot easier than last year in terms of math?
Yea that's what my partner the math guy told me too. So that's fun :D

Re: Astronomy C

Posted: March 21st, 2017, 10:43 am
by syo_astro
Technically this is a science competition, so the math is never supposed to be particularly hard ;). At the same time, algebra, units, and graph reading surprisingly or not does result in many mistakes, so...

Re: Astronomy C

Posted: March 21st, 2017, 5:44 pm
by Avogadro
Technically this is a science competition, so the math is never supposed to be particularly hard ;). At the same time, algebra, units, and graph reading surprisingly or not does result in many mistakes, so...
Science = math

Or at least when literally every event you do has a lot of math, at least. I guess I might be speaking from a bit of a biased standpoint.

So once one has exhausted the first page of Google for every concept and object, what would you all recommend going towards? Any textbook recommendations?

Re: Astronomy C

Posted: March 21st, 2017, 7:06 pm
by syo_astro
I am staunchly opposed to the idea that science = math. But then I am also biased, just in the opposite direction :P. I just figure when you can have a class mostly about observations and concepts that logically come from those observations, science isn't just math...of course I'm not saying math is unrelated to science, but science is certainly not *purely* math (as your equals sign might imply :P).

The 1st page of google for every *concept*? The concepts sometimes can have quite a bit of depth depending on what search terms you use! In fact, varying up search terms and looking at the first 3 - 5 links sometimes gets you more than just a basic search. One specific tip is you can look at research papers if you're looking for new concepts or ways of looking at objects (it takes practice, but mainly just read the abstract/intro/conclusion).

Re: Astronomy C

Posted: March 29th, 2017, 2:57 pm
by Unome
Question: why do higher-mass stars have the radiative layer outside the convective layer while low(er) mass stars are the opposite?

Re: Astronomy C

Posted: March 29th, 2017, 3:18 pm
by Adi1008
Question: why do higher-mass stars have the radiative layer outside the convective layer while low(er) mass stars are the opposite?
Greater mass means greater pressures and temperatures at the center of the star, creating a large temperature gradient between the core and the outer layers - this results in convection. Furthermore, the outer layers have a very low density, so energy flows through them more efficiently by radiation

Re: Astronomy C

Posted: March 30th, 2017, 8:47 am
by Unome
Question: why do higher-mass stars have the radiative layer outside the convective layer while low(er) mass stars are the opposite?
Greater mass means greater pressures and temperatures at the center of the star, creating a large temperature gradient between the core and the outer layers - this results in convection. Furthermore, the outer layers have a very low density, so energy flows through them more efficiently by radiation
Ok; so do larger stars also contain an inner radiative section? (and why does this section exist in lower-mass stars)

Also, unrelated; does anyone know anything about the concept of the lifetime of an atomic transition? Apparently it's related to the spectral line width, but I can't really understand most of the documents that talk about it (too much math).

Re: Astronomy C

Posted: April 3rd, 2017, 6:08 am
by Magikarpmaster629
So I already talked about this with East and Lumosityfan on IRC earlier and got a good answer, but I'll ask it again because I think it's really interesting:

In a typical CO white dwarf, a type Ia supernova will occur after carbon burning begins due to the runoff nuclear reaction that follows it. But from what I found (Carrol and Ostlie's Introduction to Modern Astrophysics) carbon burning begins at 1.3 solar masses. The "vanilla" explanation (as someone on stackexchange put it) for the type Ia supernova is that it occurs after the Chandrasekhar limit is reached; the value of which is 1.4 solar masses. Comparing these, I suspected that this was a misconception- the type Ia supernova is (at least somewhat) unrelated to the Chandrasekhar limit, and does not need to reach it to explode, although white dwarfs cannot surpass that limit (except in special cases). East and Lumosityfan seemed to confirm this, and the white dwarf does not need to hit the limit; anyone else have input on this?

Re: Astronomy C

Posted: April 3rd, 2017, 6:41 am
by Unome
So I already talked about this with East and Lumosityfan on IRC earlier and got a good answer, but I'll ask it again because I think it's really interesting:

In a typical CO white dwarf, a type Ia supernova will occur after carbon burning begins due to the runoff nuclear reaction that follows it. But from what I found (Carrol and Ostlie's Introduction to Modern Astrophysics) carbon burning begins at 1.3 solar masses. The "vanilla" explanation (as someone on stackexchange put it) for the type Ia supernova is that it occurs after the Chandrasekhar limit is reached; the value of which is 1.4 solar masses. Comparing these, I suspected that this was a misconception- the type Ia supernova is (at least somewhat) unrelated to the Chandrasekhar limit, and does not need to reach it to explode, although white dwarfs cannot surpass that limit (except in special cases). East and Lumosityfan seemed to confirm this, and the white dwarf does not need to hit the limit; anyone else have input on this?
I've also heard that the values were different and unrelated (though I tend to stick with 1.4 for most tests since that's what usually gets the points).

Re: Astronomy C

Posted: April 3rd, 2017, 7:32 am
by jonboyage
So I already talked about this with East and Lumosityfan on IRC earlier and got a good answer, but I'll ask it again because I think it's really interesting:

In a typical CO white dwarf, a type Ia supernova will occur after carbon burning begins due to the runoff nuclear reaction that follows it. But from what I found (Carrol and Ostlie's Introduction to Modern Astrophysics) carbon burning begins at 1.3 solar masses. The "vanilla" explanation (as someone on stackexchange put it) for the type Ia supernova is that it occurs after the Chandrasekhar limit is reached; the value of which is 1.4 solar masses. Comparing these, I suspected that this was a misconception- the type Ia supernova is (at least somewhat) unrelated to the Chandrasekhar limit, and does not need to reach it to explode, although white dwarfs cannot surpass that limit (except in special cases). East and Lumosityfan seemed to confirm this, and the white dwarf does not need to hit the limit; anyone else have input on this?
I've also heard that the values were different and unrelated (though I tend to stick with 1.4 for most tests since that's what usually gets the points).
I wonder if the rotation of the object has anything to do with it? When a star is rotating rapidly, its centrifugal pseudo-force would have an effect on the pressure on the core, increasing the total mass that the white dwarf can accommodate. The conventional mass of 1.4 I believe is for non-rotating objects.

As for the 1.3, can you explain how fusion makes the white dwarf unstable? In my head, I imagine that fusion would have the effect of decreasing the "load" on the degenerate matter and help prevent collapse.