The entry geometry and velocity of planetary debris into the Roche sphere of a white dwarf

Veras, Dimitri; Georgakarakos, Nikolaos; Mustill, Alexander J.; Malamud, Uri; Cunningham, Tim; Dobbs-Dixon, Ian

doi:10.1093/mnras/stab1667

Cited by 19 publications

(14 citation statements)

References 113 publications

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“…Debris disks are often proposed as the sources of WD metal pollution where the objects can be scattered toward the central host by planets (Bonsor et al 2011;Debes et al 2012;Mustill et al 2018;Smallwood et al 2018Smallwood et al , 2021Veras et al 2021). Alternatively, several other authors worked on transporting asteroids toward the WD with the help of stellar companions, galactic tides and/or stellar flybys (Veras et al 2014c;Bonsor & Veras 2015;Petrovich & Muñoz 2017).…”

Section: Discussionmentioning

confidence: 99%

“…In unstable multi-planet systems (Debes & Sigurdsson 2002;Veras et al 2013;Mustill et al 2014;Veras et al 2016), the surviving planets may scatter planetesimals inward to the WD (Frewen & Hansen 2014;Mustill et al 2018;Veras et al 2021). To allow instability to occur, the inter-planet spacing must be relatively close; however, this spacing is often too wide for many of the observed exoplanetary systems (Fabrycky et al 2014).…”

Section: Discussionmentioning

confidence: 99%

“…A widely accepted scenario is that such metal accretion is caused by consumption of tidally disrupted asteroids (Jura 2003(Jura , 2008, probably scattered onto the WD by planets in the system (Bonsor et al 2011;Debes et al 2012;Frewen & Hansen 2014;Mustill et al 2018;Smallwood et al 2018Smallwood et al , 2021Veras et al 2021;Li et al 2021). For instance, a planetary system, stable over the main sequence, may be destabilised during the WD phase because of the increased planet-star mass ratio and hence the increase in the interplanetary forcing compared to the central gravity (Debes & Sigurdsson 2002;Veras et al 2013;Mustill et al 2014;Veras et al 2016;Mustill et al 2018;Maldonado et al 2020aMaldonado et al ,b, 2021.…”

Section: Introductionmentioning

confidence: 99%

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Metal pollution of the solar white dwarf by solar system small bodies

Li,

Mustill,

Davies

2021

Preprint

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White dwarfs (WDs) often show metal lines in their spectra, indicating accretion of asteroidal material. Our Sun is to become a WD in several Gyr. Here, we examine how the solar WD accretes from the three major small body populations: the main belt asteroids (MBAs), Jovian trojan asteroids (JTAs), and trans-Neptunian objects (TNOs). Owing to the solar mass loss during the giant branch, 40% of the JTAs are lost but the vast majority of MBAs and TNOs survive. During the WD phase, objects from all three populations are sporadically scattered onto the WD, implying ongoing accretion. For young cooling ages 100 Myr, accretion of MBAs predominates; our predicted accretion rate ∼ 10 6 g/s falls short of observations by two orders of magnitude. On Gyr timescales, thanks to the consumption of the TNOs that kicks in 100 Myr, the rate oscillates around 10 6 − 10 7 g/s until several Gyr and drops to ∼ 10 5 g/s at 10 Gyr. Our solar WD accretion rate from 1 Gyr and beyond agrees well with those of the extrasolar WDs. We show that for the solar WD, the accretion source region evolves in an inside-out pattern. Moreover, in a realistic small body population with individual sizes covering a wide range as WD pollutants, the accretion is dictated by the largest objects. As a consequence, the accretion rate is lower by an order of magnitude than that from a population of bodies of a uniform size and the same total mass and shows greater scatter.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Metal pollution of the solar white dwarf by solar system small bodies

Li,

Mustill,

Davies

2021

Preprint

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“…However, what we can confidently conclude from our data is that efficient mechanisms must still exist at large cooling times to deliver planetary materials to the immediate vicinity of white dwarfs. Recent results suggest that accretion events at late cooling times can be more easily achieved when instabilities are generated by terrestrial than by Jovian planets (Veras et al 2021). The latter quickly eject asteroids and debris out of the system early in the evolution of the white dwarf, while smaller planets can continue to generate instabilities at larger cooling times.…”

Section: Comparison To the Predictions Of Dynamical Simulationsmentioning

confidence: 99%

No evidence for a strong decrease of planetesimal accretion in old white dwarfs

Blouin,

2021

Preprint

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A large fraction of white dwarfs are accreting or have recently accreted rocky material from their planetary systems, thereby "polluting" their atmospheres with elements heavier than helium. In recent years, the quest for mechanisms that can deliver planetesimals to the immediate vicinity of their central white dwarfs has stimulated a flurry of modelling efforts. The observed time evolution of the accretion rates of white dwarfs through their multi-Gyr lifetime is a crucial test for dynamical models of evolved planetary systems. Recent studies of cool white dwarfs samples have identified a significant decrease of the mass accretion rates of cool, old white dwarfs over Gyr timescales. Here, we revisit those results using updated white dwarf models and larger samples of old polluted H-and He-atmosphere white dwarfs. We find no compelling evidence for a strong decrease of their time-averaged mass accretion rates for cooling times between 1 and 8 Gyrs. Over this period, the mass accretion rates decrease by no more than a factor of the order of 10, which is one order of magnitude smaller than the decay rate found in recent works. Our results require mechanisms that can efficiently and consistently deliver planetesimals inside the Roche radius of white dwarfs over at least 8 Gyrs.

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“…systems stable on the main sequence (MS) become unstable in the WD phase of the stellar host (Debes & Sigurdsson 2002). The exploration of one-planet (Bonsor et al 2011;Debes et al 2012;Frewen & Hansen 2014;Veras et al 2021), two-planet (Smallwood et al 2018) and three-planet systems (Mustill et al 2018), interacting with planetesimal belts similar to the Edgeworth-Kuiper belt and the Asteroid Belt in the Solar System, partially explains the accretion rates observed in polluted WDs, when some stringent conditions are fullfilled, such as a planetesimal disc orders of magnitude more massive than the Asteroid Belt of the Solar System (Bonsor et al 2011;Debes et al 2012) or low-mass planets with very eccentric orbits (e > 0.4, Frewen & Hansen 2014,Mustill et al 2018,Veras et al 2021.…”

Section: Introductionmentioning

confidence: 99%

Disentangling the parameter space: The role of planet multiplicity in triggering dynamical instabilities on planetary systems around white dwarfs

Maldonado,

Villaver,

Mustill

et al. 2022

Preprint

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Planets orbiting intermediate and low-mass stars are in jeopardy as their stellar hosts evolve to white dwarfs (WDs) because the dynamics of the planetary system changes due to the increase of the planet:star mass ratio after stellar mass-loss. In order to understand how the planet multiplicity affects the dynamical stability of post-main sequence (MS) systems, we perform thousands of N-body simulations involving planetary multiplicity as the variable and with a controlled physical and orbital parameter space: equal-mass planets; the same orbital spacing between adjacent planet's pairs; and orbits with small eccentricities and inclinations. We evolve the host star from the MS to the WD phase following the system dynamics for 10 Gyr. We find that the fraction of dynamically active simulations on the WD phase for two-planet systems is 10.2 +1.2 −1.0 -25.2 +2.5 −2.2 % and increases to 33.6 +2.3 −2.2 -74.1 +3.7 −4.6 % for the six-planet systems, where the ranges cover different ranges of initial orbital separations. Our simulations show that the more planets the system has, the more systems become unstable when the star becomes a WD, regardless of the planet masses and range of separations. Additional results evince that simulations with low-mass planets (1, 10 M ⊕ ) lose at most two planets, have a large fraction of systems undergoing orbit crossing without planet losses, and are dynamically active for Gyr time-scales on the WD's cooling track. On the other hand, systems with high-mass planets (100, 1000 M ⊕ ) lose up to five planets, preferably by ejections, and become unstable in the first few hundred Myr after the formation of the WD.

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The entry geometry and velocity of planetary debris into the Roche sphere of a white dwarf

Cited by 19 publications

References 113 publications

Metal pollution of the solar white dwarf by solar system small bodies

Metal pollution of the solar white dwarf by solar system small bodies

No evidence for a strong decrease of planetesimal accretion in old white dwarfs

Disentangling the parameter space: The role of planet multiplicity in triggering dynamical instabilities on planetary systems around white dwarfs

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