Astronomy C

[ichaelm]

First of all, Trees, that question isn't a question. But I'll assume that you meant to ask how many times brighter one star was than the other. In that case, the inverse square law is all you'd need. Flavorflav was assuming that it was asking for the difference in astronomical magnitudes which is also be a reasonable question, but he took the log base 10, despite the fact that magnitudes correspond to a factor of about 2.51, not 10, so you'd need to take the log base 2.51.

[salcedam]

Just letting you guys know that there are a couple typos on the formula sheet that's linked in the wiki. For the formula relating the luminosity of a star and its radius and temperature, it says L/Lsun = (R/Rsun)(T/Tsun) when it should be L/Lsun = (R/Rsun)^2(T/Tsun)^4. Also in the formula for Hubble's Law, it says that Hubble's constant is 20 km/s/Mpc. It should be 70 km/s/Mpc. And the last typo is on the page of constants. It says that the luminosity of the sun is 3.826E26 kg. Kilograms obviously does not make sense as a unit for luminosity. That should be W (or watts).

[Flavorflav]

First of all, Trees, that question isn't a question. But I'll assume that you meant to ask how many times brighter one star was than the other. In that case, the inverse square law is all you'd need. Flavorflav was assuming that it was asking for the difference in astronomical magnitudes which is also be a reasonable question, but he took the log base 10, despite the fact that magnitudes correspond to a factor of about 2.51, not 10, so you'd need to take the log base 2.51.

DoH! You're right, of course - make that about 3 magnitudes brighter.

[AlphaTauri]

Hm, does anyone have a definitive answer for the distance of Tycho's SNR? Chandra says 13,000 LY, but every other source I have says somewhere between 7500 and 10,000 LY.

[Infinity Flat]

Hm, does anyone have a definitive answer for the distance of Tycho's SNR? Chandra says 13,000 LY, but every other source I have says somewhere between 7500 and 10,000 LY.

SIMBAD has it at 2.8 +- 0.4 kpc. Which is about 9000 ly.
SIMBAD
Original Paper

[Swag]

Once again, I'm lost. Can someone explain like, everything? Or send me to places where I can gather some notes (by some, I mean a lot)

[Infinity Flat]

Once again, I'm lost. Can someone explain like, everything? Or send me to places where I can gather some notes (by some, I mean a lot)

Each person is allowed a binder or a laptop.
Description: "Students will demonstrate an understanding of the basic concepts of mathematics and physics relating to stellar evolution and type Ia supernovas."

The rule book gives a more detailed description of the types of questions and information that you should be familiar with.

A good portion of the event relates to specific deep space objects (DSO). You should know about the studies of these objects and what makes them interesting or unique. Information on these objects is best found by simply Googling the object. Honestly. CHANDRA and Wikipedia links are the best.

For the general topics, it can be helpful to look at the web pages for introductory courses in astronomy. These can sometimes have lecture notes and exercises.

As far as specific sites, Astronomy Notes is a FANTASTIC introductory resource. If you don't understand something, go here first.

As always, the scioly wiki page and all of Wikipedia are useful resources.

[AnimeWatermelon]

Can someone please tell me what the main things to study for this event are? It's my first year with Astronomy and I'm a bit nervous...

[AlphaTauri]

That's what the rules are for, y'know. :P

However, since you asked nicely, the focus for Astro this year is "stellar evolution and Type Ia supernovas", so you'll definitely want to learn about that, including related topics like the H-R diagram and different kinds of varstars. Also, take a look at the DSO list for this year and research 'em - the DSOs are on nearly every test you'll ever see. Once you've got that, learn the math, since tests WILL ask you to calculate things. There's not really a set "list" of equations/problem types, but some of the more common ones are: blackbody radiation, luminosity/magnitude, calculating distance (possibly using parallax or distance modulus), redshift, and rotational/orbital velocity.

After that...just go out on the internet and learn about astronomy/astrophysics (I recommend finding a college course and going through that, researching topics that come up) - nearly anything is fair game in this event, even if not specifically mentioned in the rules!

[syo_astro]

Does anyone know what astronomy is like at states compared to regionals, in terms of how specific the questions get/how far they would go outside the rules or about topics stated (would they ask about random astronauts and current events or would they be more likely to ask highly specific questions about DSOs)? Thank you for any feedback.

[Infinity Flat]

Does anyone know what astronomy is like at states compared to regionals, in terms of how specific the questions get/how far they would go outside the rules or about topics stated (would they ask about random astronauts and current events or would they be more likely to ask highly specific questions about DSOs)? Thank you for any feedback.

IMO, Astronomy is one of those events that doesn't really change too much between regionals and state. The only thing that's really been consistent is that state and national tests tend to be longer than those at regionals. Otherwise, everything is really up to the whim and style of the test writer/

[yousmellchinese123]

Can someone walk me through what I am doing wrong in the MN Regionals Test on the test exchange # 27?

So, they gave the light curve of the Cepheid Variable.
I determined the average apparent magnitude to be + 24.9.
I then said that the period was 25 days.
I used this in the period luminosity relationship graph and determined the absolute magnitude to be -5.24.
Then I plugged everything into the distance Modulus and I keep getting a different answer from the answer key.
Am I doing something wrong?

* Before I posted this I noticed that I didn't convert, I tried converting and my answer was still off.

[AlphaTauri]

Are you getting 3.48 E7 ly (1.07 E7 pc)?

RandomPerson and I both tried the question independently and both of us got the answer above - I'd say key is wrong, unless all three of us are doing the same thing wrong and not realizing it.

I did try extremes (using the peaks and troughs for app. mag., and using 20 for the period since it appears to be a little less than 25 days), but none of those alterations make the actual answer agree with the key.

[bookluvr-yoyo39]

can someone explain to me exactly how their got that answer for #27 from the minnesota test? i am confused and would like if there are specific steps, please... thank you!

[bookluvr-yoyo39]

can someone explain to me exactly how their got that answer for #27 from the minnesota test? i am confused and would like if there are specific steps, please... thank you!