White dwarfs are often found in binary systems with orbital periods ranging from tens of minutes to hours in which they can accrete gas from their companion stars. In about 15 per cent of these binaries, the magnetic field of the white dwarf is strong enough (at 106 gauss or more) to channel the accreted matter along field lines onto the magnetic poles1,2. The remaining systems are referred to as ‘non-magnetic’, because until now there has been no evidence that they have a magnetic field that is strong enough to affect the accretion dynamics. Here we report an analysis of archival optical observations of the ‘non-magnetic’ accreting white dwarf in the binary system MV Lyrae, whose light curve displays quasi-periodic bursts of about 30 minutes duration roughly every 2 hours. The timescale and amplitude of these bursts indicate the presence of an unstable, magnetically regulated accretion mode, which in turn implies the existence of magnetically gated accretion3,4,5, in which disk material builds up around the magnetospheric boundary (at the co-rotation radius) and then accretes onto the white dwarf, producing bursts powered by the release of gravitational potential energy. We infer a surface magnetic field strength for the white dwarf in MV Lyrae of between 2 × 104 gauss and 1 × 105 gauss, too low to be detectable by other current methods. Our discovery provides a new way of studying the strength and evolution of magnetic fields in accreting white dwarfs and extends the connections between accretion onto white dwarfs, young stellar objects and neutron stars, for which similar magnetically gated accretion cycles have been identified6,7,8,9.
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Patterson, J. The DQ Herculis stars. Publ. Astron. Soc. Pacif. 106, 209–238 (1994)
Cropper, M. The Polars. Space Sci. Rev. 54, 195–295 (1990)
Syunyaev, R. A. & Shakura, N. I. Disk reservoirs in binary systems and prospects for observing them. Sov. Astron. Lett. 3, 138–141 (1977)
Spruit, H. C. & Taam, R. E. An instability associated with a magnetosphere–disk interaction. Astrophys. J. 402, 593–604 (1993)
D’Angelo, C. R. & Spruit, H. C. Accretion discs trapped near corotation. Mon. Not. R. Astron. Soc. 420, 416–429 (2012)
Patruno, A., Watts, A., Klein Wolt, M., Wijnands, R. & van der Klis, M. 1 Hz flaring in SAX J1808.4–3658: flow instabilities near the propeller stage. Astrophys. J. 707, 1296–1309 (2009)
Patruno, A. & D’Angelo, C. 1 Hz flaring in the accreting millisecond pulsar NGC 6440 X-2: disk trapping and accretion cycles. Astrophys. J. 771, 94 (2013)
Bagnoli, T. in’t Zand, J. J. M., D’Angelo, C. R. & Galloway, D. K. A population study of type II bursts in the Rapid Burster. Astrophys. J. 449, 268 (2015)
Aspin, C., Reipurth, B., Herczeg, G. J. & Capak, P. The 2008 extreme outburst of the young eruptive variable star EX Lupi. Astrophys. J. 719, L50–L55 (2010)
Dhillon, V. S., Jones, D. H. P. & Marsh, T. R. Observations of the eclipsing nova like variable DW Ursae in a low state. Mon. Not. R. Astron. Soc. 266, 859–871 (1994)
Groot, P. J., Rutten, R. G. M. R. & Van Paradijs, J. SW Sextantis in an excited, low state. Astron. Astrophys. 368, 183–196 (2001)
Gänsicke, B. T. et al. TT Arietis: the low state revisited. Astron. Astrophys. 347, 178–184 (1999)
Thorstensen, J. R. et al. PG0027+260: an example of a class of cataclysmic variables with mysterious, but consistent, behavior. Astron. J. 102, 272–283 (1991)
Honeycutt, R. K. & Kafka, S. Characteristics of high-state/low-state transitions in VY Sculptoris stars. Astron. J. 128, 1279–1293 (2004)
Rosino, L., Romano, G. & Marziani, P. Photometric and spectroscopic observations of MV Lyrae from 1968 to 1991. Publ. Astron. Soc. Pacif. 105, 51–58 (1993)
Hameury, J.-M. & Lasota, J.-P. VY Sculptoris stars as magnetic cataclysmic variables. Astron. Astrophys. 394, 231–239 (2002)
Leach, R., Hessman, F. V., King, A. R., Stehle, R. & Mattei, J. The light curves of VY Scl stars. Mon. Not. R. Astron. Soc. 305, 225–230 (1999)
Skillman, D. R., Patterson, J. & Thorstensen, J. R. Superhumps in cataclysmic binaries. IV. MV Lyrae. Publ. Astron. Soc. Pacif. 107, 545–550 (1995)
Linnell, A. P. et al. MV Lyrae in low, intermediate, and high states. Astrophys. J. 624, 923–933 (2005)
Scaringi, S. et al. The universal nature of accretion-induced variability: the rms–flux relation in an accreting white dwarf. Mon. Not. R. Astron. Soc. 421, 2854–2860 (2012)
Scaringi, S. et al. Accretion-induced variability links young stellar objects, white dwarfs, and black holes. Sci. Adv. 1, e1500686 (2015)
Dobrotka, A., Mineshige, S. & Ness, J.-U. Rms–flux relation and fast optical variability simulations of the nova-like system MV Lyr. Mon. Not. R. Astron. Soc. 447, 3162–3169 (2015)
Hoard, D. W. et al. The hot white dwarf in the cataclysmic variable MV Lyrae. Astrophys. J. 604, 346–356 (2004)
Hertfelder, M. & Kley, W. Wave mediated angular momentum transport in astrophysical boundary layers. Astron. Astrophys. 579, A54 (2015)
D’Angelo, C. R. & Spruit, H. C. Episodic accretion on to strongly magnetic stars. Mon. Not. R. Astron. Soc. 406, 1208–1219 (2010)
Wynn, G. A., King, A. R. & Horne, K. A magnetic propeller in the cataclysmic variable AE Aquarii. Mon. Not. R. Astron. Soc. 286, 436–446 (1997)
Knevitt, G., Wynn, G. A., Vaughan, S. & Watson, M. G. Black holes in short period X-ray binaries and the transition to radiatively inefficient accretion. Mon. Not. R. Astron. Soc. 437, 3087–3102 (2014)
Godon, P. et al. An online catalog of cataclysmic variable spectra from the Far-Ultraviolet Spectroscopic Explorer. Astrophys. J. Suppl. Ser. 203, 23 (2012)
Herbig, G. H. EX Lupi: history and spectroscopy. Astron. J. 133, 2679–2683 (2007)
Banzatti, A., Pontoppidan, K. M., Bruderer, S., Muzerolle, J. & Meyer, M. R. Depletion of molecular gas by an accretion outburst in a protoplanetary disk. Astrophys. J. 798, 6 (2015)
Jenkins, J. M. et al. Overview of the Kepler science processing pipeline. Astrophys. J. 713, L87–L91 (2010)
Gilliland, R. L. et al. Initial characteristics of Kepler short cadence data. Astrophys. J. 713, L160–L163 (2010)
Baran, A. S. Spurious frequencies in the Kepler short cadence data. Acta Astron. 63, 203–224 (2013)
Scaringi, S. et al. Broad-band timing properties of the accreting white dwarf MV Lyrae. Mon. Not. R. Astron. Soc. 427, 3396–3405 (2012)
Frank, J., King, A. & Raine, D. J. Accretion Power in Astrophysics 3rd edn (Cambridge Univ. Press, 2002)
Klúzniak, W. Disk Accretion onto Weakly Magnetized Neutron Stars. PhD thesis, Stanford Univ. (1987)
Panei, J. A., Althaus, L. G. & Benvenuto, O. G. Mass–radius relations for white dwarf stars of different internal compositions. Astron. Astrophys. 353, 970–977 (2000)
Meyer, F. & Meyer-Hofmeister, E. Accretion disk evaporation by a coronal siphon flow. Astron. Astrophys. 288, 175–182 (1994)
Scaringi, S. A physical model for the flickering variability in cataclysmic variables. Mon. Not. R. Astron. Soc. 438, 1233–1241 (2014)
Dobrotka, A., Ness, J.-U., Mineshige, S. & Nucita, A. A. XMM-Newton observation of MV Lyr and the sandwiched model confirmation. Mon. Not. R. Astron. Soc. 468, 1183–1197 (2017)
Godon, P., Sion, E. M., Balman, S. & Blair, W. P. Modifying the standard disk model for the ultraviolet spectral analysis of disk-dominated cataclysmic variables. I. The novalikes MV Lyrae, BZ Camelopardalis, and V592 Cassiopeiae. Astrophys. J. 846, 52 (2017)
Kuijpers, J. & Kuperus, M. A magnetic explanation for the Rapid Burster. Astron. Astrophys. 286, 491–496 (1994)
Shakura, N. I. & Sunyaev, R. A. Black holes in binary systems. Observational appearance. Astron. Astrophys. 24, 337–355 (1973)
Pavklenko, E. P. MV Lyrae in the last low state in 1995–1996. Odessa Astron. Publ. 9, 38 (1996)
Lasota, J.-P. The disc instability model of dwarf novae and low-mass X-ray binary transients. New Astron. Rev. 45, 449–508 (2001)
Baptista, R. & Bortoletto, A. Eclipse mapping of the flickering sources in the dwarf nova V2051 Ophiuchi. Astron. J. 128, 411–425 (2004)
This paper includes data collected by the Kepler mission. Funding for the Kepler mission is provided by the NASA Science Mission directorate. We acknowledge with thanks the variable star observations from the AAVSO International Database contributed by observers worldwide and used in this research. Some of the data were obtained from the Barbara A. Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non-Hubble Space Telescope data is provided by the NASA Office of Space Science via grant NNX09AF08G and by other grants and contracts. P.J.G. acknowledges support from the Erskine programme run by the University of Canterbury.
The authors declare no competing financial interests.
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Scaringi, S., Maccarone, T., D’Angelo, C. et al. Magnetically gated accretion in an accreting ‘non-magnetic’ white dwarf. Nature 552, 210–213 (2017). https://doi.org/10.1038/nature24653
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