Localized thermonuclear bursts from accreting magnetic white dwarfs

S Scaringi; P J Groot; C Knigge; A J Bird; E Breedt; D A H Buckley; Y Cavecchi; N D Degenaar; D de Martino; C Done; M Fratta; K Iłkiewicz; E Koerding; J-P Lasota; C Littlefield; C F Manara; M O'Brien; P Szkody; F X Timmes

doi:10.1038/s41586-022-04495-6

Localized thermonuclear bursts from accreting magnetic white dwarfs

Nature. 2022 Apr;604(7906):447-450. doi: 10.1038/s41586-022-04495-6. Epub 2022 Apr 20.

Authors

S Scaringi¹, P J Groot^{2

3

4}, C Knigge⁵, A J Bird⁵, E Breedt⁶, D A H Buckley^{3

4

7}, Y Cavecchi⁸, N D Degenaar⁹, D de Martino¹⁰, C Done¹¹, M Fratta¹¹, K Iłkiewicz¹¹, E Koerding², J-P Lasota^{12

13}, C Littlefield^{14

15}, C F Manara¹⁶, M O'Brien¹¹, P Szkody¹⁵, F X Timmes^{17

18}

Affiliations

¹ Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham, UK. simone.scaringi@durham.ac.uk.
² Department of Astrophysics/IMAPP, Radboud University, Nĳmegen, the Netherlands.
³ South African Astronomical Observatory, Cape Town, South Africa.
⁴ Department of Astronomy, University of Cape Town, Rondebosch, South Africa.
⁵ School of Physics and Astronomy, University of Southampton, Southampton, UK.
⁶ Institute of Astronomy, University of Cambridge, Cambridge, UK.
⁷ Department of Physics, University of the Free State, Bloemfontein, South Africa.
⁸ Instituto de Astronomía, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
⁹ Anton Pannekoek Institute for Astronomy, University of Amsterdam, Amsterdam, the Netherlands.
¹⁰ INAF-Osservatorio Astronomico di Capodimonte, Naples, Italy.
¹¹ Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham, UK.
¹² Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Warsaw, Poland.
¹³ Institut d'Astrophysique de Paris, CNRS et Sorbonne Universités, UMR 7095, Paris, France.
¹⁴ Department of Physics, University of Notre Dame, Notre Dame, IN, USA.
¹⁵ Department of Astronomy, University of Washington, Seattle, WA, USA.
¹⁶ European Southern Observatory, Garching, Germany.
¹⁷ School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA.
¹⁸ Joint Institute for Nuclear Astrophysics-Center for the Evolution of the Elements, Notre Dame, IN, USA.

PMID: 35444319
DOI: 10.1038/s41586-022-04495-6

Abstract

Nova explosions are caused by global thermonuclear runaways triggered in the surface layers of accreting white dwarfs^1-3. It has been predicted^4-6 that localized thermonuclear bursts on white dwarfs can also take place, similar to type-I X-ray bursts observed in accreting neutron stars. Unexplained rapid bursts from the binary system TV Columbae, in which mass is accreted onto a moderately strong magnetized white dwarf from a low-mass companion, have been observed on several occasions in the past 40 years^7-11. During these bursts, the optical/ultraviolet luminosity increases by a factor of more than three in less than an hour and fades in around ten hours. Fast outflows have been observed in ultraviolet spectral lines⁷, with velocities of more than 3,500 kilometres per second, comparable to the escape velocity from the white dwarf surface. Here we report on optical bursts observed in TV Columbae and in two additional accreting systems, EI Ursae Majoris and ASASSN-19bh. The bursts have a total energy of approximately 10^-6 times than those of classical nova explosions (micronovae) and bear a strong resemblance to type-I X-ray bursts^12-14. We exclude accretion or stellar magnetic reconnection events as their origin and suggest thermonuclear runaway events in magnetically confined accretion columns as a viable explanation.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.