TESS light curves of two new magnetic cataclysmic variables: an asynchronous polar at the period minimum, and an eclipsing system with a large spin-to-orbit ratio
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| Format: | Preprint |
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2026
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| _version_ | 1866910120188837888 |
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| author | Littlefield, Colin Ilkiewicz, Krystian Mason, Paul A. Garnavich, Peter Scaringi, Simone |
| author_facet | Littlefield, Colin Ilkiewicz, Krystian Mason, Paul A. Garnavich, Peter Scaringi, Simone |
| contents | A recent development in the study of magnetic cataclysmic variable stars (mCVs) has been the identification of asynchronously spinning mCVs with orbital periods <2 h that have significantly higher white dwarf spin-to-orbital period ratios than their longer-period counterparts. We report the discovery of two additional mCVs in this class. The first, Gaia21akb, is a candidate asynchronous polar at the period minimum. While TESS photometry cannot, in isolation, lead to a conclusive identification of the orbital period, the probable orbital period of 1.29 h would be the second-shortest of any known polar and would result in a spin-to-orbit ratio of 0.9879. The second system in our study, ZTF18aazmehw, is an eclipsing mCV with a 1.50 h orbital period and a spin-to-orbit ratio of 0.867. Contrary to expectations for an asynchronous polar, ZTF18aazmehw does not show discernible evidence of pole switching and might possess a disk-like structure. The increasing number of short-period asynchronous mCVs with large spin-to-orbit ratios lends credence to theoretical predictions that asynchronously rotating mCVs with sufficiently strong white dwarf magnetic fields can achieve synchronization when their orbital separations have shrunk sufficiently. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2603_18143 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | TESS light curves of two new magnetic cataclysmic variables: an asynchronous polar at the period minimum, and an eclipsing system with a large spin-to-orbit ratio Littlefield, Colin Ilkiewicz, Krystian Mason, Paul A. Garnavich, Peter Scaringi, Simone Solar and Stellar Astrophysics A recent development in the study of magnetic cataclysmic variable stars (mCVs) has been the identification of asynchronously spinning mCVs with orbital periods <2 h that have significantly higher white dwarf spin-to-orbital period ratios than their longer-period counterparts. We report the discovery of two additional mCVs in this class. The first, Gaia21akb, is a candidate asynchronous polar at the period minimum. While TESS photometry cannot, in isolation, lead to a conclusive identification of the orbital period, the probable orbital period of 1.29 h would be the second-shortest of any known polar and would result in a spin-to-orbit ratio of 0.9879. The second system in our study, ZTF18aazmehw, is an eclipsing mCV with a 1.50 h orbital period and a spin-to-orbit ratio of 0.867. Contrary to expectations for an asynchronous polar, ZTF18aazmehw does not show discernible evidence of pole switching and might possess a disk-like structure. The increasing number of short-period asynchronous mCVs with large spin-to-orbit ratios lends credence to theoretical predictions that asynchronously rotating mCVs with sufficiently strong white dwarf magnetic fields can achieve synchronization when their orbital separations have shrunk sufficiently. |
| title | TESS light curves of two new magnetic cataclysmic variables: an asynchronous polar at the period minimum, and an eclipsing system with a large spin-to-orbit ratio |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2603.18143 |