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Predicting realistic radio emission from compact star-planet systems. Online Supplementary Material

Thursday 4 September 2025, by Corentin Louis

This collection contains figures and movies showing the results of star-planet interaction simulations using the ExPRES code for three different exoplanetary systems: Tau Bootis, HD 189733, and HD 179949. This collection supplements Appendix B and C of Chebly et al. (2025a) “Predicting realistic radio emission from compact star-planet systems”, submitted to Astronomy & Astrophysics

  • DOI: 10.25935/4pks-d207
  • Publisher: PADC
  • License: CC-BY 4.0
  • Citation: Chebly, J. J., Louis, C. K., Strugarek, A., J. D. Alvarado Gómez, P. Zarka (2025). Predicting realistic radio emission from compact star-planet systems. Online Supplementary Material (Version 1.0) [Data set]. PADC. https://doi.org/10.25935/4pks-d207/

Link to data repository

For each exoplanet name, data directories are hierarchically organised by Poynting flux values (for HD189733 and HD179949 only), and electron energy. See the Description section below for more details.

Description

This data collection contains pre-computed ExPRES Star-Planet Interaction simulation runs for three different exoplanetary systems, Tau Boootis, HD189733 and HD179949, used in Chebly et al. (2025a), with various parameter sets:

  • Magnetic Field and density Models based on ZDI maps from AWSoM stellar wind simulations (see Chebly et al., 2023). Different cases are proposed for HD 189733 and HD179949 based on four different poynting flux. Only one case is proposed for Tau Bootis
  • Electron energy: 1, 20 or 100 keV. Note that for the different values of Poynting flux explored (other than 1e6) in the case of HD189733 and HD179949, only on simulation at 20 keV was computed
  • CMI Mechanism that controls the beaming pattern beaming: Loss Cone
  • Beaming thickness: 1°
  • Waves in RX mode.
  • Near-source refraction are taken into account as the density can be very high close to the studied stars.
  • Sources are set on magnetic field line connecting the star to the exoplanet at each time step.
  • The observer is set at Earth.
  • ExPRES Version 1.4 (Louis et al. 2025) was used.

The data files contain the modelled following parameters: polarization, theta, fp, fc, obs latitude, CML (obs longitude), obs distance, srcfreqmax, srcLongitude, src pos (source position). Detailed informations are available in Louis et al., 2019.

The data files are provided in CDF format, and the ExPRES input files are JSON files. The magnetic field and density models are supplied in csv format (1 file per field line, in a zip file).

Coverage

  • October 2010 to April 2011 for Tau Bootis
  • October 2009 to April 2010 for HD179949
  • June 2006 to December 2006 for HD189733

Results

Supplement to Appendix B: Different electron energy exploration
Tau Bootis

Figure B.1
Frequency–time diagrams for the Tau Boo system, shown across the 7 simulations epochs (from October 2010 to April 2011, top to bottom). Each row corresponds to one epoch. The first three columns represent different electron energies for a loss cone distribution: 1 keV, 20 keV, and 100 keV (from left to right).

HD179949

Figure B.2
Frequency–time diagrams for the HD 179949. system, shown across the 7 simulations epochs (from October 2009 to April 2010, top to bottom). Each row corresponds to one epoch. The first three columns represent different electron energies for a loss cone distribution: 1 keV, 20 keV, and 100 keV (from left to right).

HD189733

Figure B.3
Frequency–time diagrams for the HD189733 system, shown across the 7 simulations epochs (from June 2006 to December 2006, top to bottom). Each row corresponds to one epoch. The first three columns represent different electron energies for a loss cone distribution: 1 keV, 20 keV, and 100 keV (from left to right).

Supplement to Appendix C: Poynting flux exploration

Figure C.1
Different Poynting flux (S/B) scenarios for HD 179949 (top) and HD 189733 (bottom) illustrating how changes in stellar wind influences star-planet interaction-induced radio emission. The colormap shows the total stellar wind pressure (sum of thermal, ram, and magnetic pressures) in pascals, with orange-red regions indicating higher pressure. The solid black circle marks the planetary orbit, and the brown contour outlines the shape of the Alfvén surface at the equator. HD 189733 exhibits a higher total pressure than HD 179949.

HD179949

Figure C.2
Simulated time-frequency diagrams for three different cases of Poynting flux (S/B) in the HD 179949 system. From left to right, the columns represent low, medium, and high S/B. Each of the seven rows corresponds to a different observational epoch, spanning from October 2009 to April 2010.

HD189733

Figure C.3
Simulated time-frequency diagrams for three different cases of Poynting flux (S/B) in the HD 189733 system. From left to right, the columns represent low, medium, and high S/B. Each of the seven rows corresponds to a different observational epoch, spanning from June to December 2006.

Acknowledgments
The authors acknowledge funding from the ERC under the European Union’s Horizon 2020 research and innovation program (grant agreement no 101020459 - Exoradio). J. J. C. and A.S. acknowledge funding from the European Research Council project ExoMagnets (grant agreement no. 101125367) and the PLATO/CNES grant at CEA/IRFU/DAp.

References

  • Chebly, J. J, J. D. Alvarado-Gómez, K. Poppenhäger, C. Garraffo. 2023. "Numerical quantification of the wind properties of cool main sequence stars". Monthly Notices of the Royal Astronomical Society, Volume 524 (October), Issue 4 , Pages 5060–5079, doi:10.1093/mnras/stad2100.
  • Chebly, J. J., C.K. Louis, A. Strugarek, J. D. Alvarado-Gómez, P. Zarka. 2025a. "Predicting realistic radio emission from compact star-planet systems". Astronomy & Astrophysics. doi:tba
  • Chebly, J. J., Louis, C. K., Strugarek, A. (2025b). ExPRES Tau Bootis Radio Emission Simulations Dataset (Version 1.0) [Data set]. PADC. https://doi.org/10.25935/9c80-w202
  • Chebly, J. J., Louis, C. K., Strugarek, A. (2025c). HD 189733 (Version 1.0) [Data set]. PADC. https://doi.org/10.25935/ce9q-n094
  • Chebly, J. J., Louis, C. K., Strugarek, A. (2025d). ExPRES HD 179949 Radio Emission Simulations Dataset (Version 1.0) [Data set]. PADC. https://doi.org/10.25935/d1h2-z977
  • Louis, C K, S L G Hess, B Cecconi, P Zarka, L Lamy, S Aicardi, and A Loh. 2019. “ExPRES: an Exoplanetary and Planetary Radio Emissions Simulator.” Astronomy and Astrophysics 627 (May): A30. doi:10.1051/0004-6361/201935161.
  • Louis, C. K., Hess, S. L. G., Cecconi, B., Zarka, P., Lamy, L., Aicardi, S., & Loh, A. (2025). maserlib/ExPRES: Version 1.4.0 (1.4.0). Zenodo. https://doi.org/10.5281/zenodo.17047296

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