Spectro Photo Interferometry of Pulsating stars

What is this?

This is a python2.7 implementation of a parallax of pulsation method for Cepheids stars, described in Mérand et al. (Astronomy & Astrophysics 584-80, 2015). This is not meant as a well written code: this is a research code published for anyone willing to use it (providing you quote the aforementioned paper and you respect the license) to study Cepheids or reproduce results from these papers:

• Mérand et al. (2015): "Cepheid distances from the SpectroPhoto-Interferometry of Pulsating Stars (SPIPS). Application to the prototypes delta Cephei and eta Aquilae"
• Breitfelder et al. (2015): "Observational calibration of the projection factor of Cepheids. I. The type II Cepheid kappa Pavonis"
• Breitfelder et al. (2016): "Observational calibration of the projection factor of Cepheids. II. Application to nine Cepheids with HST/FGS parallax measurements"
• Kervella et al. (2017): "Observational calibration of the projection factor of Cepheids. III. The long-period Galactic Cepheid RS Puppis"

Recent changes

Be aware that some changes have occurred recently (Nov 2017). If you have previous scripts, they will likely not run anymore:

• the names of the filters have change: they now do mirror the names of the XML files
• the "title=" keyword is gone from the "model" function, you should now use "starName="

On the other hand, the export to FITS has been fixed! you can now add "exportFits=True" to the "model" and a FITS file would be exported containing the data, the parameters of the model and the model itself.

Quick Start / Example

Quick Start:

• download all files
• in python2.7: import delta_cep.py
  • this will load spips.py
  • first time you load spips.py, lots of models will be downloaded: ATLAS9 models and SATLAS models.
• run delta_cep.show(delta_cep.p_fourier) to show the model with Fourier parameters
• run delta_cep.show(delta_cep.p_splines) to show the model with Splines parameters
• run delta_cep.fit(delta_cep.p_splines) to run a fit. Check the inside of the function to see how it works.

The result of the model is shown below:

• the upper left panel (a) shows the phased radial velocity data (points) and model (line)
• the middle left panel (b) shows the phased effective temperature data (points) and model (line)
• the lower left panel (c) shows the phased interferometric angular diameter data (points) and model (lines). Note that the different colors show the impact of the effects of the interferometric baseline on the diameter measurements, due to the presence of an circum-stellar envelop
• the panels on the right hand side (d to v) show the photometric data.

delta_cep.fitsDemo(mode='export') will export the model and the data to a FITS file (delta_cep.fits), which can be read using delta_cep.fitsDemo(mode='import'). Note that delta_cep.fitsDemo(mode='import') recomputes the model, rather than plotting the one in the FITS files. One can easily write their own routines to read and display the FITS file created by SPIPS, as they are self-explanatory.

Dependencies and known issues

• numpy
• scipy (version<0.19): The code is accelerated using scipy.weave which has been deprecated in scipy version 0.19. Hence SPIPS currently only runs in a downgraded version of scipy of 0.18.
• astropy.io.fits for exporting / importing models in FITS format

License (BSD)

Copyright (c) 2017, Antoine Mérand All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.