article published yes S. G. Parsons author A. J. Brown author S. L. Casewell author S. P. Littlefair author Joannes C van Roestel author 4d122fc8-6083-11f0-87a5-97d68b860333 A. Rebassa-Mansergas author R. Murillo-Ojeda author M. Zorotovic author M. R. Schreiber author S. Bagnulo author M. A. Stroet author N. Castro Segura author V. S. Dhillon author M. J. Dyer author J. A. Garbutt author M. J. Green author D. Jarvis author M. R. Kennedy author P. Kerry author J. Mccormac author J. Munday author I. Pelisoli author E. Pike author D. I. Sahman author A. Yates author IlCa department It is predicted that half or more of all cataclysmic variables (CVs) should have evolved past the period minimum and now exist as so-called period bouncers where a white dwarf should be accreting from a Roche lobe filling substellar companion. However, this prediction stands in stark contrast to observations, where only a few per cent of CVs are found in this evolutionary phase. A potential solution to this discrepancy is that a magnetic field emerges from within the white dwarf after the system has reached the period minimum. The transfer of angular momentum from the spin of the white dwarf into the orbit then pushes the two stars apart, detaching them for potentially billions of years. Here we present the discovery of ZTF J021804.16+071152.93, a detached 0.69 +- 0.01 M⁠, 19 MG magnetic white dwarf plus 37 +- 5MJup brown dwarf binary with an orbital period of 1.7 h. The kinematics of the system indicate that it is a high probability member of the Galactic thick disc. However, this strongly disagrees with the much younger age of the system obtained from the white dwarf parameters, implying that the system may have been accreting in the past. This system is therefore consistent with having detached as a result of the emergence of the magnetic field of the white dwarf when the system was still mass transferring, and may represent the ultimate fate for many (perhaps even most) CVs. https://research-explorer.ista.ac.at/download/21780/21834/2026_MNRAS_Parsons.pdf application/pdfno Oxford University Press2026 eng 0035-8711 1365-2966 2603.1288810.1093/mnras/stag521 5474 Parsons, S. G., Brown, A. J., Casewell, S. L., Littlefair, S. P., van Roestel, J. C., Rebassa-Mansergas, A., … Yates, A. (2026). ZTF J021804.16+071152.93: A dead cataclysmic variable and potential solution to the missing period bouncer cataclysmic variables. <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press. <a href="https://doi.org/10.1093/mnras/stag521">https://doi.org/10.1093/mnras/stag521</a> Parsons SG, Brown AJ, Casewell SL, et al. ZTF J021804.16+071152.93: A dead cataclysmic variable and potential solution to the missing period bouncer cataclysmic variables. <i>Monthly Notices of the Royal Astronomical Society</i>. 2026;547(4). doi:<a href="https://doi.org/10.1093/mnras/stag521">10.1093/mnras/stag521</a> S. G. Parsons <i>et al.</i>, “ZTF J021804.16+071152.93: A dead cataclysmic variable and potential solution to the missing period bouncer cataclysmic variables,” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 547, no. 4. Oxford University Press, 2026. Parsons, S. G., et al. “ZTF J021804.16+071152.93: A Dead Cataclysmic Variable and Potential Solution to the Missing Period Bouncer Cataclysmic Variables.” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 547, no. 4, stag521, Oxford University Press, 2026, doi:<a href="https://doi.org/10.1093/mnras/stag521">10.1093/mnras/stag521</a>. Parsons, S. G., A. J. Brown, S. L. Casewell, S. P. Littlefair, Joannes C van Roestel, A. Rebassa-Mansergas, R. Murillo-Ojeda, et al. “ZTF J021804.16+071152.93: A Dead Cataclysmic Variable and Potential Solution to the Missing Period Bouncer Cataclysmic Variables.” <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press, 2026. <a href="https://doi.org/10.1093/mnras/stag521">https://doi.org/10.1093/mnras/stag521</a>. Parsons SG, Brown AJ, Casewell SL, Littlefair SP, van Roestel JC, Rebassa-Mansergas A, Murillo-Ojeda R, Zorotovic M, Schreiber MR, Bagnulo S, Stroet MA, Castro Segura N, Dhillon VS, Dyer MJ, Garbutt JA, Green MJ, Jarvis D, Kennedy MR, Kerry P, Mccormac J, Munday J, Pelisoli I, Pike E, Sahman DI, Yates A. 2026. ZTF J021804.16+071152.93: A dead cataclysmic variable and potential solution to the missing period bouncer cataclysmic variables. Monthly Notices of the Royal Astronomical Society. 547(4), stag521. S.G. Parsons, A.J. Brown, S.L. Casewell, S.P. Littlefair, J.C. van Roestel, A. Rebassa-Mansergas, R. Murillo-Ojeda, M. Zorotovic, M.R. Schreiber, S. Bagnulo, M.A. Stroet, N. Castro Segura, V.S. Dhillon, M.J. Dyer, J.A. Garbutt, M.J. Green, D. Jarvis, M.R. Kennedy, P. Kerry, J. Mccormac, J. Munday, I. Pelisoli, E. Pike, D.I. Sahman, A. Yates, Monthly Notices of the Royal Astronomical Society 547 (2026). 217802026-05-03T22:01:37Z2026-05-07T07:51:58Z