EL CMi: Confirmation of triaxial pulsation theory
Creators
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1.
Polish Academy of Sciences
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2.
Massachusetts Institute of Technology
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3.
Instituto de Astrofísica de Canarias
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4.
University of La Laguna
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5.
University of Oxford
- 6. Amateur Astronomer, Glendale, AZ, 85308, USA
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7.
California Institute of Technology
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8.
North-West University
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9.
University of Central Lancashire
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10.
University of Warwick
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11.
Yunnan Observatories
- 12. International Centre of Supernovae, Yunnan Key Laboratory, Kunming, 650216, PR China
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13.
Goddard Space Flight Center
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14.
Search for Extraterrestrial Intelligence
Abstract
Triaxial pulsators are a recently discovered group of oscillating stars in close binary systems that pulsate around three axes at the same time. It has recently been theoretically shown that new types of pulsation modes, the tidally tilted standing (TTS) modes, can arise in these stars. We report the first detection of a quadrupole TTS oscillation mode in the pulsating component of the binary system EL CMi following an analysis of TESS space photometry. Two dipole oscillations around different axes in the orbital plane are present as well. In addition, we characterize the binary system using new radial velocity measurements and PHOEBE as well as simultaneous spectral energy distribution and light curve modeling. The pulsating primary component has properties typical of a δ Scuti star, but has accreted and is still accreting mass from its Roche-lobe filling companion. The donor star is predicted to evolve into a low-mass helium white dwarf. EL CMi demonstrates the potential of asteroseismic inferences of the structure of stars in close binaries before and after mass transfer and in three spatial dimensions.
Copyright and License
© The Authors 2025. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Acknowledgement
GH and AM both thank the Polish National Center for Science (NCN) for supporting this study through grant 2021/43/B/ST9/02972 and Filiz Kahraman Aliçavuş for her comments on the spectrum of the target. DJ acknowledges support from the Agencia Estatal de Investigación del Ministerio de Ciencia, Innovación y Universidades (MCIU/AEI) under grant “Nebulosas planetarias como clave para comprender la evolución de estrellas binarias” and the European Regional Development Fund (ERDF) with reference PID-2022-136653NA-I00 (DOI: 10.13039/501100011033). DJ also acknowledges support from the Agencia Estatal de Investigación del Ministerio de Ciencia, Innovación y Universidades (MCIU/AEI) under grant “Revolucionando el conocimiento de la evolución de estrellas poco masivas” and the European Union Next Generation EU/PRTR with reference CNS2023-143910 (DOI: 10.13039/501100011033). H-LC is supported by the National Key R&D Program of China (grant Nos. 2021YFA1600403), the National Natural Science Foundation of China (grant Nos. 12288102, 12333008 and 12422305). VK acknowledges support from NSF grant AST-2206814. This paper includes data collected by the TESS mission. Funding for the TESS mission is provided by the NASA Science Mission Directorate. The QLP data used in this work were obtained from MAST (https://dx.doi.org/10.17909/t9-r086-e880), hosted by the Space Telescope Science Institute (STScI). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5–26555. This work also presents results from the European Space Agency (ESA) space mission Gaia. Gaia data are being processed by the Gaia Data Processing and Analysis Consortium (DPAC). Funding for the DPAC is provided by national institutions, in particular the institutions participating in the Gaia MultiLateral Agreement (MLA). The Gaia mission website is https://www.cosmos.esa.int/gaia. The Gaia archive website is https://archives.esac.esa.int/gaia. This research has also made use of the VizieR catalogue access tool, CDS, Strasbourg, France. Software: This paper made use of the following codes/packages: LIGHTKURVE (Lightkurve Collaboration 2018), IRAF (Tody 1986) SPECTRUM (Gray & Corbally 1994) PERIOD04 (Lenz & Breger 2005) MESA (Paxton et al. 2011, 2013, 2015, 2018, 2019; Jermyn et al. 2023).
Data Availability
We make all files needed to recreate our MESA-BINARY results publicly available at Zenodo: https://zenodo.org/records/15745684
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Additional details
Related works
- Is new version of
- Discussion Paper: arXiv:2507.21255 (arXiv)
- Is supplemented by
- Dataset: https://zenodo.org/records/15745684 (URL)
- Dataset: 10.17909/t9-r086-e880 (DOI)
Funding
- National Science Center
- 2021/43/B/ST9/02972
- Agencia Estatal de Investigación
- European Commission
- PID-2022-136653NA-I00
- NextGenerationEU
- CNS2023-143910
- National Key R&D Program of China
- 2021YFA1600403
- National Natural Science Foundation of China
- 12288102
- National Natural Science Foundation of China
- 12333008
- National Natural Science Foundation of China
- 12422305
- National Science Foundation
- AST-2206814
- NASA Science Mission Directorate
- National Aeronautics and Space Administration
- NAS 5-26555
Dates
- Accepted
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2025-07-27
- Available
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2025-10-10Published online