Thermal-diffusional Instability in White Dwarf Flames: Regimes of Flame Pulsation

ABSTRACT The discovery of a giant planet candidate orbiting the white dwarf WD 1856+534 with an orbital period of 1.4 d poses the questions of how the planet reached its current position. We here reconstruct the evolutionary history of the system assuming common envelope evolution as the main mechanism that brought the planet to its current position. We find that common envelope evolution can explain the present configuration if it was initiated when the host star was on the asymptotic giant branch, the separation of the planet at the onset of mass transfer was in the range 1.69–2.35 au, and if in addition to the orbital energy of the surviving planet either recombination energy stored in the envelope or another source of additional energy contributed to expelling the envelope. We also discuss the evolution of the planet prior to and following common envelope evolution. Finally, we find that if the system formed through common envelope evolution, its total age is in agreement with its membership to the Galactic thin disc. We therefore conclude that common envelope evolution is at least as likely as alternative formation scenarios previously suggested such as planet–planet scattering or Kozai–Lidov oscillations.

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Mass transfer in double white dwarf binaries

New Astronomy Reviews ◽

10.1016/j.newar.2008.03.019 ◽

2008 ◽

Vol 51 (10-12) ◽

pp. 878-883 ◽

Cited By ~ 2

Author(s):

Juhan Frank

Keyword(s):

Mass Transfer ◽

White Dwarf

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Bayesian constraints on the origin and geology of exo-planetary material using a population of externally polluted white dwarfs

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab736 ◽

2021 ◽

Author(s):

John H D Harrison ◽

Amy Bonsor ◽

Mihkel Kama ◽

Andrew M Buchan ◽

Simon Blouin ◽

...

Keyword(s):

Solar System ◽

White Dwarf ◽

Bayesian Model ◽

Total Mass ◽

White Dwarfs ◽

Bulk Composition ◽

Planetary Systems ◽

The Moon ◽

Planetary Bodies ◽

Nearby Stars

Abstract White dwarfs that have accreted planetary bodies are a powerful probe of the bulk composition of exoplanetary material. In this paper, we present a Bayesian model to explain the abundances observed in the atmospheres of 202 DZ white dwarfs by considering the heating, geochemical differentiation, and collisional processes experienced by the planetary bodies accreted, as well as gravitational sinking. The majority (>60%) of systems are consistent with the accretion of primitive material. We attribute the small spread in refractory abundances observed to a similar spread in the initial planet-forming material, as seen in the compositions of nearby stars. A range in Na abundances in the pollutant material is attributed to a range in formation temperatures from below 1,000 K to higher than 1,400 K, suggesting that pollutant material arrives in white dwarf atmospheres from a variety of radial locations. We also find that Solar System-like differentiation is common place in exo-planetary systems. Extreme siderophile (Fe, Ni or Cr) abundances in 8 systems require the accretion of a core-rich fragment of a larger differentiated body to at least a 3σ significance, whilst one system shows evidence that it accreted a crust-rich fragment. In systems where the abundances suggest that accretion has finished (13/202), the total mass accreted can be calculated. The 13 systems are estimated to have accreted masses ranging from the mass of the Moon to half that of Vesta. Our analysis suggests that accretion continues for 11Myrs on average.

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The effects of different Type Ia SN yields on Milky Way chemical evolution

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab293 ◽

2021 ◽

Vol 503 (3) ◽

pp. 3216-3231

Author(s):

Marco Palla

Keyword(s):

Chemical Evolution ◽

White Dwarf ◽

Time Distribution ◽

Milky Way ◽

Massive Stars ◽

Abundance Patterns ◽

Type Ia ◽

Low Metallicity ◽

Explosion Mechanism ◽

Chemical Evolution Model

ABSTRACT We study the effect of different Type Ia SN nucleosynthesis prescriptions on the Milky Way chemical evolution. To this aim, we run detailed one-infall and two-infall chemical evolution models, adopting a large compilation of yield sets corresponding to different white dwarf progenitors (near-Chandrasekar and sub-Chandrasekar) taken from the literature. We adopt a fixed delay time distribution function for Type Ia SNe, in order to avoid degeneracies in the analysis of the different nucleosynthesis channels. We also combine yields for different Type Ia SN progenitors in order to test the contribution to chemical evolution of different Type Ia SN channels. The results of the models are compared with recent LTE and NLTE observational data. We find that ‘classical’ W7 and WDD2 models produce Fe masses and [α/Fe] abundance patterns similar to more recent and physical near-Chandrasekar and sub-Chandrasekar models. For Fe-peak elements, we find that the results strongly depend either on the white dwarf explosion mechanism (deflagration-to-detonation, pure deflagration, double detonation) or on the initial white dwarf conditions (central density, explosion pattern). The comparison of chemical evolution model results with observations suggests that a combination of near-Chandrasekar and sub-Chandrasekar yields is necessary to reproduce the data of V, Cr, Mn and Ni, with different fractions depending on the adopted massive stars stellar yields. This comparison also suggests that NLTE and singly ionized abundances should be definitely preferred when dealing with most of Fe-peak elements at low metallicity.

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Direct detection of atomic dark matter in white dwarfs

Journal of High Energy Physics ◽

10.1007/jhep03(2021)166 ◽

2021 ◽

Vol 2021 (3) ◽

Author(s):

David Curtin ◽

Jack Setford

Keyword(s):

Dark Matter ◽

Energy Loss ◽

Cooling Rate ◽

White Dwarf ◽

White Dwarfs ◽

Luminosity Function ◽

Direct Detection ◽

Matter Density ◽

Mixing Parameter ◽

First Time

Abstract Dark matter could have a dissipative asymmetric subcomponent in the form of atomic dark matter (aDM). This arises in many scenarios of dark complexity, and is a prediction of neutral naturalness, such as the Mirror Twin Higgs model. We show for the first time how White Dwarf cooling provides strong bounds on aDM. In the presence of a small kinetic mixing between the dark and SM photon, stars are expected to accumulate atomic dark matter in their cores, which then radiates away energy in the form of dark photons. In the case of white dwarfs, this energy loss can have a detectable impact on their cooling rate. We use measurements of the white dwarf luminosity function to tightly constrain the kinetic mixing parameter between the dark and visible photons, for DM masses in the range 10−5–105 GeV, down to values of ϵ ∼ 10−12. Using this method we can constrain scenarios in which aDM constitutes fractions as small as 10−3 of the total dark matter density. Our methods are highly complementary to other methods of probing aDM, especially in scenarios where the aDM is arranged in a dark disk, which can make direct detection extremely difficult but actually slightly enhances our cooling constraints.

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