Astronomy C

[antoine_ego]

Wait, do they have the test posted anywhere yet?

[Magikarpmaster629]

cross-sectional area

I think you're confused on what flux is. Flux is the power released over a surface per unit area. So instead of using cross-sectional area, use the surface area, which, for a star (roughly a sphere), is 4piR^2.

[Unome]

cross-sectional area

I think you're confused on what flux is. Flux is the power released over a surface per unit area. So instead of using cross-sectional area, use the surface area, which, for a star (roughly a sphere), is 4piR^2.

Isn't the light only coming from the circular projection of the star?

Edit: No idea why I used cross-sectional area, probably because I was doing a Remote test right before this, where I was using cross-sectional area for the planetary energy balance equation. For the way this question is phrased it would be surface area (although I guess it didn't matter in this case).

[Adi1008]

Any idea when the MIT test is coming out? I looked over our tests, and while we got 10th, we got every single DSO question wrong (literally no points). Our other team did the same. Any reason for this? The rest of the test seemed easier than I expected.

This is likely something you've already done, but make sure to check the answers you put down with the answer key to see if they're correct. Last year, we got only 0.5 points on the second page of the answer sheet when nearly every question was answered correctly according to the answer key. The answers you guys put could have been correct and they either weren't counted (grading error) or the proctors didn't write down the point total for that page and they were counted as correct. Essentially, don't assume they're all wrong just because you didn't get points for them; check the answer key too

On a side note: on the MIT test, there was one question asking what "pulsating white dwarfs with periods of 100-1000 seconds" would be called. I put down DAV stars thinking it was the same thing as ZZ Ceti stars. Is there a reason why DAV stars wouldn't be accepted while ZZ Ceti stars would be (like small differences between the two, nomenclature, convention, etc)? To my knowledge of them (which comes almost entirely from studying GD 165 from last year lol) they're just different names for the same thing

[Unome]

Any idea when the MIT test is coming out? I looked over our tests, and while we got 10th, we got every single DSO question wrong (literally no points). Our other team did the same. Any reason for this? The rest of the test seemed easier than I expected.

This is likely something you've already done, but make sure to check the answers you put down with the answer key to see if they're correct. Last year, we got only 0.5 points on the second page of the answer sheet when nearly every question was answered correctly according to the answer key. The answers you guys put could have been correct and they either weren't counted (grading error) or the proctors didn't write down the point total for that page and they were counted as correct. Essentially, don't assume they're all wrong just because you didn't get points for them; check the answer key too

On a side note: on the MIT test, there was one question asking what "pulsating white dwarfs with periods of 100-1000 seconds" would be called. I put down DAV stars thinking it was the same thing as ZZ Ceti stars. Is there a reason why DAV stars wouldn't be accepted while ZZ Ceti stars would be (like small differences between the two, nomenclature, convention, etc)? To my knowledge of them (which comes almost entirely from studying GD 165 from last year lol) they're just different names for the same thing

Is a DAV star necessarily a ZZ Ceti? I'm completely unaware of the historical context.

Now that you've posted, I can ask my question without double-posting within a day:

#20c - how to do? Is it just supposed to be taking the luminosities and just using the area of a circle?

Also, I notice there were no ranges of answers for 21 on the key; was I the only one that didn't read the amplitudes as being exactly in a 3:1 ratio? (I also missed the deviation from zero during the test )

[Magikarpmaster629]

Any idea when the MIT test is coming out? I looked over our tests, and while we got 10th, we got every single DSO question wrong (literally no points). Our other team did the same. Any reason for this? The rest of the test seemed easier than I expected.

This is likely something you've already done, but make sure to check the answers you put down with the answer key to see if they're correct. Last year, we got only 0.5 points on the second page of the answer sheet when nearly every question was answered correctly according to the answer key. The answers you guys put could have been correct and they either weren't counted (grading error) or the proctors didn't write down the point total for that page and they were counted as correct. Essentially, don't assume they're all wrong just because you didn't get points for them; check the answer key too

On a side note: on the MIT test, there was one question asking what "pulsating white dwarfs with periods of 100-1000 seconds" would be called. I put down DAV stars thinking it was the same thing as ZZ Ceti stars. Is there a reason why DAV stars wouldn't be accepted while ZZ Ceti stars would be (like small differences between the two, nomenclature, convention, etc)? To my knowledge of them (which comes almost entirely from studying GD 165 from last year lol) they're just different names for the same thing

I think you should technically be considered correct, however simply the term ZZ Ceti is better known than DAV. Also I think DAV stars are only for white dwarf class DA- there are also DBV, DCV, DOV stars and others.

[Ashernoel]

Wright state: eh fun test. Derivations were cool, but I hope the grader gives partial credit for units / little mistakes and follows work. I'm new to science Olympiad, do graders usually give partial credit for show work problems??

What did you guys think of the test??

[Unome]

Wright state: eh fun test. Derivations were cool, but I hope the grader gives partial credit for units / little mistakes and follows work. I'm new to science Olympiad, do graders usually give partial credit for show work problems??

What did you guys think of the test??

Usually if there's a reasonable range of answers, such as for questions based on the magnitude of type Ia supernovae, good event supervisors will allow for some variation (see the MIT test from last year on their website).

[Ashernoel]

Alright thanks! For one answer I put nm instead of pm and messed up a derivation by subtracting when I should have divided by the end. It was a 15 or problem so I hope to get a little partial credit :0

[antoine_ego]

Also, I notice there were no ranges of answers for 21 on the key; was I the only one that didn't read the amplitudes as being exactly in a 3:1 ratio? (I also missed the deviation from zero during the test )

My guess as to why there's no range of answers is the number of sig figs you could get. You could really only get 1 sig fig, so therefore, your answer would be the same as well.