## Astronomy C

yousmellchinese123
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### Re: Astronomy C

AlphaTauri wrote: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.
Yes I did, thank you. I was getting frustrated for a while there.

Bookluvr: There are links out there that explain how to calculate the distance. Searching "Cepheid Variable Star Distance Measurement" or something of the sort is a good starting point! (:
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bookluvr-yoyo39
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### Re: Astronomy C

thank you! the links i found helped! but, how did you find the absolute magnitude from the light curve? or is it a given variable in the equation?
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yousmellchinese123
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### Re: Astronomy C

bookluvr-yoyo39 wrote:thank you! the links i found helped! but, how did you find the absolute magnitude from the light curve? or is it a given variable in the equation?
There is a relationship that you need to find using this: http://outreach.atnf.csiro.au/education ... tions.html
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pjgscioisamazing
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### Re: Astronomy C

yousmellchinese123 wrote:
bookluvr-yoyo39 wrote:thank you! the links i found helped! but, how did you find the absolute magnitude from the light curve? or is it a given variable in the equation?
There is a relationship that you need to find using this: http://outreach.atnf.csiro.au/education ... tions.html
Also for Cepheids (Type I Classical Cepheids that is) there is an equation using the period to find the Absolute Magnitude:

M=-2.81log(P)-1.43

For an RR Lyrae Variable, the Absolute Magnitude is always around +.75, and for Type Ia Supernovae it is always around -19.5
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### Re: Astronomy C

Hmm, I've always used -19.3 for Type Ia supernovae. I've seen -19.3, -19.5, and -19.6, and it does sometimes affect the results. When they don't provide a constant to use, I just go with -19.3, but how exactly are participants supposed to know which value to use?
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Infinity Flat
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### Re: Astronomy C

EASTstroudsburg13 wrote:Hmm, I've always used -19.3 for Type Ia supernovae. I've seen -19.3, -19.5, and -19.6, and it does sometimes affect the results. When they don't provide a constant to use, I just go with -19.3, but how exactly are participants supposed to know which value to use?
It's probably best to use -19.3, unless otherwise stated in the problem.
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pjgscioisamazing
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### Re: Astronomy C

Infinity Flat wrote:
EASTstroudsburg13 wrote:Hmm, I've always used -19.3 for Type Ia supernovae. I've seen -19.3, -19.5, and -19.6, and it does sometimes affect the results. When they don't provide a constant to use, I just go with -19.3, but how exactly are participants supposed to know which value to use?
It's probably best to use -19.3, unless otherwise stated in the problem.
According to the National Powerpoint from the Summer Coaches Institute says -19.5, so I've been using that one since I saw the powerpoint. So unless the test says something else, I usually use -19.5
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### Re: Astronomy C

Anyone have a recommendation for the Carina Nebulae pics as there are like 100 different ones. Whenever I don't recognize one at this point or think I have the image in the 3-5ish I saved for DSO I have just been putting Carina Nebulae if it resembles it in anyway...
Last edited by Osennecho on February 29th, 2012, 5:28 pm, edited 1 time in total.
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### Re: Astronomy C

Okay, comp is pretty soon and I'm still kinda shaky. I mean I've done a lot of research, but like what exactly should I know about type 1a supernova? And as for the known DSO's, what should I know about them?

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Osennecho
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### Re: Astronomy C

Swag wrote:Okay, comp is pretty soon and I'm still kinda shaky. I mean I've done a lot of research, but like what exactly should I know about type 1a supernova? And as for the known DSO's, what should I know about them?

As is always the answer for Science Olympiad. Know all the information
No, but seriously you can be asked anything and everything related to the DSO's or Stellar Ev let alone 1a supernova.
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