Monday, July 26, 2010

Some Results! Statistical distinctiveness


disclaimer: using 30 random observations over 1000 days and constant 2.5 solar mass

0.18 planeticity (predicted for 2.5 mass solar metallicity stars) is inconsistent with zero above 20 sampled stars. :) The prediction is 3.58 planets with 1.63 standard deviation. Great!

But, only at 100 stars does 0.18 planeticity start being inconsistent with 0.08 planeticity. I think it will only be by combining this survey with other work that we will be able to say for sure that intermediate mass stars do have a larger planeticity :( As shown in the graph, a survey drawn from the 18% distribution could easily fall in the 8% distribution area.
On the bright side, my average mass might end up being greater than 2.5, so the planeticity will be greater and it will be easier to tell them apart. Also, standard low mass stars are populated by a different population of planets which would probably be unobservable around intermediate mass red giants. 100 good targets will probably be an upper limit for how many good targets I can find (maybe), and I don't now how time will limit it.

I did approximate the multiple survey standard deviation as coming from a Gaussian, which might be wrong. It kinda looks triangular shaped. I don't know how to save IDL graphs so I can't really show an example in the blog. Anyway, I used the criterion:
| nplanets(0.18)- nplanets(0.08)| > 2 * sqrt( sigma(0.18)^2+ sigma(0.08)^2 )
to determine distinctiveness.
Both the average and the standard deviations were pulled from 100 trial surveys.

So the assigning planet program has been altered to actually pull from the mass law (Making my Own Distribution Functions) and a uniform distribution for radius over 0.6 to 3 AU. I struggled with algebraic manipulation and units for a while, but now it works quite fine. Also, returnability is calculated by RMS > 3 *noise instead of seeing if rv_fit_mp returns the same parameters. This is much more rapid and efficient. 4 seconds for 100 surveys, so I can run 100 surveys per step and still get many more steps in. Also, since we probably won't actually have incredibly much control over observing schedule beyond how many observations, observing dates are now completely randomized.

Goals for tomorrow:
1. import in array of magnitudes and masses from current available stars
2. calculate noise
3. Make sure MC parameters and time scales are good
3. Start running MC program AND SEE WHAT HAPPENS!!!!

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