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astronomy4ever wrote:Does anyone know (or know where I could find) the apparent or absolute magnitudes for IGR J17091, LHa115-N19 or Rho Ophiuchi Cloud complex?

I would say for this one those three objects aren't exact stars or galaxies with so exact apparent/absolute magnitudes. I could see maybe finding apparent magnitudes for these, maybe try searching up the name with apparent or absolute magnitude. But I don't think you'd find much. Good luck, hope this helped!
Edit: I meant to also say that these do have objects in them that maybe you could search and find abs/app mags for, but only if you want that extra preparation (hehe, with astro never know I guess).

So about the Schwarzschild Radius equation. Is the mass 'M' measured in solar masses?\

Equation:

R=2GM/c squared

astro124 wrote:So about the Schwarzschild Radius equation. Is the mass 'M' measured in solar masses?\

Equation:

R=2GM/c squared

Depends on your value for G. My bets are on kilograms

If you're using standard units for G (m^3/(s^2/kg)) and c (m/s), then yes, the equation does require M to be in kg to spit out the right answer.

Keeping track of your units is, unfortunately, very important if you want to get an answer that makes sense (as I learned the hard way on a Regionals test) >.>

Okay, so about the Stefan-Boltzmann Equation for finding the luminosity of a star, doesn't look like this:

L=4π σ R² T⁴

Or am I supposed to the version on the wiki equation sheet?

Also, and I know this isn't the place for rules clarification, but is there any proper procedure for rounding during the Astronomy event?

So for example do all of our numbers need to follow some round to the tenth rule (even if it isn't the final answer).

I feel that without such as universal rule, we would all get different answers, and I hope that the event supervisor knows that.

The equation you have is just a combination of the Stefan-Boltzmann Law and the "regular" luminosity equation.

The Stefan-Boltzmann equation (E= σT⁴) actually measures flux, which in this case is "energy emitted per area".

Luminosity, in its most basic form, is L = [energy per area] * [area], so we can get the luminosity of a spherical star by multiplying the Stefan-Boltzmann equation by that for the SA of a sphere:

L = (σT⁴) * (4πR²)

which we can rearrange to get L=4π σ R² T⁴.

Edit: In response to your second post, I typically use sig figs when rounding. My state supervisor requires answers to be given to sig fig accuracy, and I feel it's a good idea to carry that over to other astro tests, since it gives a definite rule for lopping off decimal places (except when you get the occasional weird test that gives you way too few sig figs to give any kind of reasonable answer...then I just play it by ear).

Do you only round your final number (answer) for a mathematical problem in sig figs or do you round all numbers to sig figs. So for example if you were multiplying two large numbers in that are both in scientific notation, would you round each of those numbers then multiply or keep the numbers as is, then round the final answer, or perhaps round all numbers?

I'd think you'd just round when you get your final answer.

Hey so this is my first year on this event, and while I've got a ton of research down, I'm having a hard time grasping the math. Are there any good sources where I can learn about it (basically from the ground up)?