bleaktwig / rr-lyrae-tpred

Collection of tests and models used to predict a RR Lyrae-class star's temperature based on its Hydrogen spectrum.

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RR Lyrae temperature prediction

The purpose of this repository is to hold a set of tests and ML-based models to predict the temperature of an RR Lyrae-class star based on the wings of its Hydrogen lines (starting with Halpha at 656 nm).

Motivation

Currently, the temperature of an RR Lyrae star at a snapshot of its phase is obtained by

  1. capturing a snapshot of its spectrum at a particular point in its phase;
  2. computing the synthetic spectrum at a given temperature; and
  3. fitting the synthetic spectrum to the observed one to find a match of the star's temperature.

While this methodology provides good results, it is quite slow: it takes about 5 minutes on an average computer. This is acceptable for small-scale datasets, but we'll need to process very large ones in the future (> 1M stars). In addition, a faster temperature prediction approach may allow us to later develop predictions across the star's phase, improving the field of study of this class of stars.

Pending tasks

  • Define the input format.
  • Get more input data.
  • Develop simple estimation models and see how well they behave.
  • Estimate the sources of uncertainty and include them on the model.
    • Wing selection.
    • Uncertainty of the flux measurement.
    • Fit error.
  • Develop a wing range selection algorithm.
  • Play around with different spectrum/flux fitting functions (Chebyshev?).
  • Play around with a model that can propagate uncertainties (Metropolis?).
  • Look into the possibility of an ML-based de-noising approach. This would broaden the range of the available input data to the noisier regions.

Recommended reading

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Collection of tests and models used to predict a RR Lyrae-class star's temperature based on its Hydrogen spectrum.


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