Formation of high-field magnetic white dwarfs from common envelopes

Nordhaus, Jason; Wellons, Sarah; Spiegel, David S.; Metzger, Brian D.; Blackman, Eric G.

doi:10.1073/pnas.1015005108

Cited by 119 publications

(123 citation statements)

References 65 publications

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“…Some 10-30% of WDs have fields of 10 4 − 10 9 G (Kawka et al 2007), and ∼ 10% have 10 3 − 10 4 G (Jordan et al 2007, Landstreet et al 2012. Nordhaus et al (2011), Tout et al (2008 and García-Berro et al (2012) have argued that strong magnetic fields in WDs are always the result of binary interactions, be it through accretion, common-envelope evolution, or mergers. In magnetic WDs, photometric variability due to spots and variable dichroic polarization open two additional avenues to measure rotation.…”

Section: Binary Wdsmentioning

confidence: 99%

Observational Clues to the Progenitors of Type Ia Supernovae

Maoz

Mannucci

Nelemans

2014

Annu. Rev. Astron. Astrophys.

965

894

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Type-Ia supernovae (SNe Ia) are important distance indicators, element factories, cosmic-ray accelerators, kinetic-energy sources in galaxy evolution, and endpoints of stellar binary evolution. It has long been clear that a SN Ia must be the runaway thermonuclear explosion of a degenerate carbon-oxygen stellar core, most likely a white dwarf (WD). However, the specific progenitor systems of SNe Ia, and the processes that lead to their ignition, have not been identified. Two broad classes of progenitor binary systems have long been considered: single-degenerate (SD), in which a WD gains mass from a non-degenerate star; and doubledegenerate (DD), involving the merger of two WDs. New theoretical work has enriched these possibilities with some interesting updates and variants. We review the significant recent observational progress in addressing the progenitor problem. We consider clues that have emerged from the observed properties of the various proposed progenitor populations, from studies of their sites -pre-and post-explosion, from analysis of the explosions themselves, and from the measurement of event rates. The recent nearby and well-studied event, SN 2011fe, has been particularly revealing. The observational results are not yet conclusive, and sometimes prone to competing theoretical interpretations. Nevertheless, it appears that DD progenitors, long considered the underdog option, could be behind some, if not all, SNe Ia. We point to some directions that may lead to future progress.

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Section: Binary Wdsmentioning

confidence: 99%

Observational Clues to the Progenitors of Type Ia Supernovae

Maoz

Mannucci

Nelemans

2014

Annu. Rev. Astron. Astrophys.

965

894

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“…Within the second scenario, magnetic white dwarfs are the result of the evolution of binary systems. In this case the magnetic field is amplified by a dynamo that operates either during the common envelope phase (Tout et al 2008;Nordhaus et al 2011) or in the hot corona produced during the merger of two white dwarfs (García-Berro et al 2012). A difficulty of these two scenarios is that detailed population synthesis studies cannot reproduce the number of stars observationally found (Ferrario et al 2015).…”

Section: Introductionmentioning

confidence: 99%

A Common Origin of Magnetism from Planets to White Dwarfs

Isern

Garcı́a–Berro

Külebi

et al. 2017

ApJL

111

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Isolated magnetic white dwarfs have field strengths ranging from kilogauss to gigagauss. However, the origin of the magnetic field has not been hitherto elucidated. Whether these fields are fossil, hence the remnants of original weak magnetic fields amplified during the course of the evolution of their progenitor stars, or are the result of binary interactions, or, finally, they are produced by other internal physical mechanisms during the cooling of the white dwarf itself, remains a mystery. At sufficiently low temperatures, white dwarfs crystallize. Upon solidification, phase separation of its main constituents, 12 C and 16 O, and of the impurities left by previous evolution occurs. This process leads to the formation of a Rayleigh-Taylor unstable liquid mantle on top of a solid core. This convective region, as it occurs in solar system planets like the Earth and Jupiter, can produce a dynamo able to yield magnetic fields of strengths of up to 0.1 MG, thus providing a mechanism that could explain magnetism in single white dwarfs.

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“…This process would be a planetary-mass analog to strong magnetic field generation via mergers and common envelope evolution of stellar-mass companions (Tout et al 2008;Nordhaus et al 2011). The results discussed below are the part of a concerted effort to determine the frequency of weak magnetic fields among polluted white dwarfs.…”

Section: Constraints On Weak Magnetismmentioning

confidence: 99%

Magnetism, X-rays and accretion rates in WD 1145+017 and other polluted white dwarf systems

Farihi

Fossati

Wheatley

et al. 2017

Monthly Notices of the Royal Astronomical Society

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This paper reports circular spectropolarimetry and X-ray observations of several polluted white dwarfs including WD 1145+017, with the aim to constrain the behavior of disk material and instantaneous accretion rates in these evolved planetary systems. Two stars with previously observed Zeeman splitting, WD 0322-019 and WD 2105-820, are detected above 5σ and B z > 1 kG, while WD 1145+017, WD 1929+011, and WD 2326+049 yield (null) detections below this minimum level of confidence. For these latter three stars, high-resolution spectra and atmospheric modeling are used to obtain limits on magnetic field strengths via the absence of Zeeman splitting, finding B * < 20 kG based on data with resolving power R ≈ 40 000. An analytical framework is presented for bulk Earth composition material falling onto the magnetic polar regions of white dwarfs, where X-rays and cyclotron radiation may contribute to accretion luminosity. This analysis is applied to X-ray data for WD 1145+017, WD 1729+371, and WD 2326+049, and the upper bound count rates are modeled with spectra for a range of plasma kT = 1 − 10 keV in both the magnetic and non-magnetic accretion regimes. The results for all three stars are consistent with a typical dusty white dwarf in a steady state at 10 8 − 10 9 g s −1 . In particular, the non-magnetic limits for WD 1145+017 are found to be well below previous estimates of up to 10 , thus suggesting the star-disk system may be average in its evolutionary state, and only special in viewing geometry.

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Formation of high-field magnetic white dwarfs from common envelopes

Cited by 119 publications

References 65 publications

Observational Clues to the Progenitors of Type Ia Supernovae

Observational Clues to the Progenitors of Type Ia Supernovae

A Common Origin of Magnetism from Planets to White Dwarfs

Magnetism, X-rays and accretion rates in WD 1145+017 and other polluted white dwarf systems

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