Astronomy C

[quizbowl]

i would be very interested. does anyone know the specific formula's and their explanations for astronomy? thank you....

This formula/constant sheet is a good start formula-wise.

[Infinity Flat]

i would be very interested. does anyone know the specific formula's and their explanations for astronomy? thank you....

This formula/constant sheet is a good start formula-wise.

Captain, my captain, your hyperlink has failed!

[rfscoach]

i would be very interested. does anyone know the specific formula's and their explanations for astronomy? thank you....

This formula/constant sheet is a good start formula-wise.

Captain, my captain, your hyperlink has failed!

Works fine for me.

[Infinity Flat]

This formula/constant sheet is a good start formula-wise.

Captain, my captain, your hyperlink has failed!

Works fine for me.

Hmm, works for me now too. Odd.

[EASTstroudsburg13]

My school hasn't been very strong over the past years at the event, and I might decide to try it this year, so does anyone have any advice, such as textbooks, study materials?

I know Infinity Flat mentioned a book somewhere in this thread. Other than that, looking up everything in the rules on the Internet should give you a good basis. You can start off with the Astronomy Wiki.

And also, if you have participated in this event, what aspect makes it difficult? Just the subject in general, a broad scope of testable material, or something else? Any feedback can help. Thank You!

Yes to everything in there pretty much. It's very broad, and there are so mnay things that can be tested on. This also depends on the event supervisor.

[Schrodingerscat]

Does anyone else agree with me on the following question:

What can parallax be used to calculate be used to calculate?
a. The composition off [sic] stars based on the spectra of their starlight
b. the temperature on the surface of a star within 1,000 light-years of Earth
c. the distance of a star within 1,000 light-years of Earth
d. the distance to stars that are extremely far away

We answered C because 1000ly is about the limit of parallax detection. However, the answer for the test was D. To me in astronomy, "extremely far" implies millions if not billions of light years, which is well beyond the limits of stellar parallax. Does anyone else have any thoughts on why D might be a valid answer over C?

[rfscoach]

Does anyone else agree with me on the following question:

What can parallax be used to calculate be used to calculate?
a. The composition off [sic] stars based on the spectra of their starlight
b. the temperature on the surface of a star within 1,000 light-years of Earth
c. the distance of a star within 1,000 light-years of Earth
d. the distance to stars that are extremely far away

We answered C because 1000ly is about the limit of parallax detection. However, the answer for the test was D. To me in astronomy, "extremely far" implies millions if not billions of light years, which is well beyond the limits of stellar parallax. Does anyone else have any thoughts on why D might be a valid answer over C?

The answer key was wrong. It happens ya know. I made a test for a Div C invite last weekend and thought I double checked my key, but when I was going over 1 of the exercises with my Div B kids on Monday I found a stupid mistake on a 5 point question. Embarrassing.

[Schrodingerscat]

I was pretty sure that it was an incorrect answer, but I was just checking with others to confirm it.

[emmamcgorray]

Does anybody know what DSOs specifically are going to be tested? I know that last year there was a list given of which DSOs were going to be emphasized. Is the list the same this year, or is it just not out yet?

[AlphaTauri]

Yeah, the DSO list is out with the rules. It's way different from last year, so you'll want to take a good look at the rules before starting to study.

Also, I can verify that the answer to that question a couple posts back should be C not D. Parallax only works up until the star is too far for us to measure any significant angle (~1000 LY).

[SilverNight]

Can someone help me with a question I have about spectra?
In the book I'm reading, it says that a emission line is produced when a thin gas is seen against a cooler background. I know what a continuous spectrum and an absorption line is, but I don't understand emission line. What does it mean by "a thin gas is seen against a cooler background"?
Another question about absorption spectra: when electrons absorb the photon of light of a specific wavelength and jump to a higher energy level, doesn't it fall right back down and send the photon back? ... So doesn't that mean there shouldn't be a dark line where the photon is absorbed?
... I hope my questions make sense and don't sound stupid...

[Schrodingerscat]

I think to your first question they mean a thin gas as opposed to very dense gases which emit continuous spectra when heated. I believe (but am not certain) that the emission lines are the result of thermal energy increasing electrons energy levels, and are brighter lines surrounded by the darker rest of the spectra. The answer to your second question is that the photon is emitted in a random direction, not necessarily in the same direction of the original photon. So certain photons from a background source such as a star will be scattered in random directions creating the absorption spectrum.

[Trees]

DSO's from the Invitationals (photos in link/on the wiki page http://scioly.org/wiki/Astronomy/DSOs )

Mira http://science.nasa.gov/science-news/sc ... 5aug_mira/
Carina Nebula http://scioly.org/wiki/File:CarinaNebula.jpg
Sirius B http://scioly.org/w/images/2/20/SirB.jpg
NGC 2440 http://apod.nasa.gov/apod/ap070215.html

Not sure which one of these were there too, though I THINK so (I think 2 are right):
Tycho's SNR http://scioly.org/w/images/d/d8/TychoSNR.jpg
Kepler's SNR http://scioly.org/w/images/8/80/KeplerSNR.jpg
Rosette Nebula http://scioly.org/w/images/3/35/Rosette.jpg

There was a total of 10; I forgot the first one. So that means about 4/10 are unknown. I'll look around. Here's the list from the rules manual:
Mira, SNR 0509-67.5, CH Cyg, Kepler's SNR, Tycho's SNR, M15, Carina Nebula, T Tauri, Sirius B, RR Lyrae, U Scorpii, Rosette Nebula, BP Psc, NGC 2440, RX J0806.3+1527, DEM L238 & L249


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Candidates. Not sure yet but when the Test comes out I'll let you all know for sure (or someone might beat me to the punch, ha) (Funny enough, both of these appear in Invitationals but not on the manual...)

Perseus A
NGC2623 [confirmed by http://scioly.org/w/images/9/90/Ast-sol.pdf ]

On the same note: http://scioly.org/w/images/6/68/AstronomyWayzata11.pdf needs the answers, heh.

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OKAY NOW TIME FOR QUESTIONS.
We were given a problem where two stars appeared to be the same brightness; however, one was about 4 times farther (or whatever number they used). We couldn't find the formula to answer this question with...

[EASTstroudsburg13]

From which invitational are these DSO's from? They really shouldn't test on DSO's from previous years, but luckily last year's list is on the wiki, so it might be useful to print it out JUST IN CASE a supervisor decides to use it.

Based on your description of the problem, the distance modulus looks like it would work. I'd link you to the wiki, but LaTeX looks like it's not working.

[Flavorflav]

It's simpler than that - inverse square law, then take the log. The more distant star must have 16 times the luminosity to be equally bright at four times the distance, so it is 1.2 magnitudes brighter absolutely.