So...
Since the mass is still way too precise, I decided to move backward and look at the cluster fitting parameters. They turn out to be extremely precise too. Way too precise.
So, I went back and looked at the fitting paper that I read and I section that didn't make since before now makes since and I may be greatly wrong as to my process. They take the original isochrone, populate the HR diagram with many,many stars from this isochrone according to the initial mass function, and make a certain percentage of them unseen binaries according to some other distribution function. This creates a density on the HR diagram that is used to compute probabilities of a data point from that isochrone. Though the code would not be incredibly hard to write, it would be computationally difficult and greatly increase the time necessary for one cluster. Is that necessary and where I am going wrong?
Before I get too overwhelmed and confused, I think I'll try this on another cluster to compare results.
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Recall what the probability is telling you. You are assuming the stars are drawn from a Gaussian in V and B-V about the isochrone. The further a point moves, the less likely that it would have been drawn from a normal distribution centered on the isochrone.
ReplyDeleteHave you tried varying the isochrone and then visually examining the scatter of the stars about it? Does a small step in mass or distance lead to huge changes in the distance of stars from the isochrone, as measured in the number of sigma (error bars)? Could it be that the error bars are too small, so that a small shift in the isochrone location results in your stars lying too many sigmas away?