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stevengiacalone / triceratops

Tool for Rating Interesting Candidate Exoplanets and Reliability Analysis of Transits Originating from Proximate Stars
https://triceratops.readthedocs.io
MIT License
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Clarify on the nearby stars included in analysis #21

Closed orionlee closed 1 year ago

orionlee commented 1 year ago

This is a question and a feature suggestion regarding nearby stars included in analysis

Question: For nearby stars with missing stellar parameters (mass, rad, or Teff), are they include in analysis?

image

If they are excluded, it might be helpful to issue a warning.

Suggestion: in the paper, it is suggested that stars with little contribution to the aperture are excluded using a relative transit depth measure.

It might be helpful to include the relative transit depth measure in target.stars, so that users can easily identify nearby stars included in the analysis.

Currently, I am doing something like this:

# stars with δs >= 1 are excluded from further analysis (section 2.1 of the paper)
target.stars["rel_tdepth"] = tdepth / target.stars["fluxratio"]

target.stars[target.stars["rel_tdepth"] < 1]  # show stars still included in the analysis
stevengiacalone commented 1 year ago

Nearby stars will never be dropped from the analysis automatically. Missing masses, radii, and Teffs are assigned Solar values if none are listed in the TIC. The user is notified when this happens when they run .calc_probs(). This is obviously not a great approximation, but it's better than omitting them from the analysis altogether. One can also manually assign values in the .stars dataframe using the results of an SED or isochrone fit, but this is left to the user.

The value "tdepth" in the .stars dataframe is the relative transit depth. Specifically, it is the depth that the nearby star would need to have to produce the transit, given the amount of flux that star is contributing the the chosen aperture. Nearby stars that would need tdepth > 1 to explain the signal are already excluded from the analysis, so no additional calculations are needed.

orionlee commented 1 year ago

Somehow I failed to notice the warnings issued in .calc_probs() for using solar values initially, but it's there when I looked at the output again.

For relative transit depth, thanks for the clarification. It could be helpful to explain it in the example.ipynb .