Scioly.org

pb5754[] wrote:

jz123sst wrote:Does anyone know if Astronomy will still be an event 2019-2020 (next year)? If so, what topics will it cover?

It definitely will be an event next year, and I'm not sure but I think the topic will be variable stars or star/planet formation.

Disclaimer: not official, but my personal experience from the past about 7 to 9 yrs or so (but still not official!!)

The exact topic changes every single year. There are some small patterns, but it really can change a lot. Also, "stellar evolution is always there" is pretty much true nowadays (it could change randomly, but at least in "recent" times it's been true...see this year: "stellar evolution" still around with *galaxies* >.>). But like I said the sub-topic is important / less predictable (though, things like light curves, spectra, images, DSOs, etc are always important...that should be clear if you have *any* two years of rules).

One of the tests I took asked me to use luminosity in lumens to find the brightness of a star. Is there a way to convert lumens to watts, because I can't see another way to solve this(we were given a distance, so I tried using L=I/(4pir^2)

SciolyHarsh wrote:One of the tests I took asked me to use luminosity in lumens to find the brightness of a star. Is there a way to convert lumens to watts, because I can't see another way to solve this(we were given a distance, so I tried using L=I/(4pir^2)

I have never heard of lumens being used in an astro test. Could you send a screencap of that specific question? The dimensions for luminosity are Watts, not Lumens, so the validity of the question seems somewhat dubious.

Hi everyone!

I've uploaded the MIT astro exam/key here, as well as some statistics from the competition. Be warned: it is really long and hard (Adi1008 and I had a bit too much fun with it :P). But hopefully everyone can learn something from it! To that effect, I've also uploaded a walkthrough of the free response questions, which (I hope) emphasizes how you should reason about the problems, and provides some resources for further reading. Keep checking back over the course of this week, as the walkthrough document will be edited to include more detailed solutions of Adi1008's questions as well.

We hope that you find this useful! As always, feel free to contact us if you have any questions.

Do you know of any good resources to learn how to use JS9? It's seems confusing and I'm not sure how to answer questions about it.

ET2020 wrote:Do you know of any good resources to learn how to use JS9? It's seems confusing and I'm not sure how to answer questions about it.

I agree that it can be confusing/intimidating at first. Keep in mind that this year, you won't actually have to use the JS9 software in competition, just be able to understand screenshots of its various functionalities.

I wrote a very basic-level introduction to JS9 here. Beyond the guide, I think it's helpful to play around on the site and see what it can do. To perform well on JS9 questions at high-level tournaments, be sure to also understand fundamental concepts in multi-wavelength astronomy, energy spectra, light curves, etc. The goal of JS9 is to be able to apply theory to understand observational data! In case you haven't seen it, there's a JS9 question on the MIT exam (see #19) and detailed solutions here, so that might give you a feel for what sort of questions to expect.

Hi all, I was reviewing over past Upenn invitational math questions to practice, and I found one that seems impossible:

https://docs.google.com/document/d/1zHq ... sp=sharing

Particularly parts B) and C). I feel like there's certain information missing? I tried multiple approaches, such as using , Kepler's third law for binary systems, and even integrating the cosine function of one of the curves with respect to time to find the distance it traveled in one period, but I couldn't seem to get the answer. It seems you need two known variables, whereas the problem only provides you with one. The given answer to B) is 1.5E7 km and the answer to C) is .09Msolar. I feel like the two parts could be answered in any order, but that's just a guess.

I'm assuming you need to use the information about the type M star to answer the question, but I don't know how.

Help would be much appreciated.

M3335 wrote:Hi all, I was reviewing over past Upenn invitational math questions to practice, and I found one that seems impossible:

Part B: Have you tried applying circular (orbital) velocity? If you know the radial velocity and the period, you should be able to figure out the radius of orbit for a given orbiting object.
Part C: If you know the mass ratio, the orbital separation, and the period, you should have two equations and two unknowns that should be solvable (the mass ratio and Kepler's third law). You really shouldn't need to do any integrals or fancy math in astro (or all events, really). I would say you'd need to do Part B first, at least it's more intuitive to.

Haven't tried the math yet, but I can try it in a bit. Not sure about the units on the y-axis though (I'd guess km/s of course)...binary star questions should be easy to write, but I've messed them up tons of times -_-. Luckily, invites have been good opportunities for me to get complaints about stuff like that (nobody lets me live down the math on two invites posted online XD), I actually do use the feedback and triple check for real tournies!

syo_astro wrote:

M3335 wrote:Hi all, I was reviewing over past Upenn invitational math questions to practice, and I found one that seems impossible:

Part B: Have you tried applying circular (orbital) velocity? If you know the radial velocity and the period, you should be able to figure out the radius of orbit for a given orbiting object.
Part C: If you know the mass ratio, the orbital separation, and the period, you should have two equations and two unknowns that should be solvable (the mass ratio and Kepler's third law). You really shouldn't need to do any integrals or fancy math in astro (or all events, really). I would say you'd need to do Part B first, at least it's more intuitive to.

Haven't tried the math yet, but I can try it in a bit. Not sure about the units on the y-axis though (I'd guess km/s of course)...binary star questions should be easy to write, but I've messed them up tons of times -_-. Luckily, invites have been good opportunities for me to get complaints about stuff like that (nobody lets me live down the math on two invites posted online XD), I actually do use the feedback and triple check for real tournies!

Ah thank you! Somehow that method slipped from my mind. I used circular velocity, and came up with around 1.49E5 km but .08Msolar, so I think the answer key may be wrong.

Anybody have the image set for the carnegie mellon test?