Do instabilities in high-multiplicity systems explain the existence of close-in white dwarf planets?

Abstract

We investigate the origin of close-in planets and related phenomena orbiting white dwarfs (WDs), which are thought to originate from orbits more distant from the star. We use the planetary architectures of the 75 multiple-planet systems (four, five and six planets) detected orbiting main-sequence stars to build 750 dynamically analogous templates that we evolve to the WD phase. Our exploration of parameter space, although not exhaustive, is guided and restricted by observations and we find that the higher the multiplicity of the planetary system, the more likely it is to have a dynamical instability (losing planets, orbit crossing and scattering), that eventually will send a planet (or small object) through a close periastron passage. Indeed, the fraction of unstable four- to six-planet simulations is comparable to the 25-50$\%$ fraction of WDs having atmospheric pollution. Additionally, the onset of instability in the four- to six-planet configurations peaks in the first Gyr of the WD cooling time, decreasing thereafter. Planetary multiplicity is a natural condition to explain the presence of close-in planets to WDs, without having to invoke the specific architectures of the system or their migration through the von Zeipel-Lidov-Kozai (ZLK) effects from binary companions or their survival through the common envelope phase.

5 pages, 4 figures, 1 table, accepted to MNRAS Letters

References in corpus (19)

• The frequency of planetary debris around young white dwarfs
• A gaseous metal disk around a white dwarf
• Foretellings of Ragnarök: World-engulfing Asymptotic Giants and the Inheritance of White Dwarfs
• Exoplanet Orbital Eccentricities Derived From LAMOST-Kepler Analysis
• Hot Jupiters and Cool Stars
• A Giant Planet Candidate Transiting a White Dwarf
• A planetesimal orbiting within the debris disc around a white dwarf star
• Accretion of a giant planet onto a white dwarf
• Planet Engulfment by ~1.5-3 Solar-Mass Red Giants
• Detectable close-in planets around white dwarfs through late unpacking
• The unbiased frequency of planetary signatures around single and binary white dwarfs using $Spitzer$ and $Hubble$
• Accounting for Incompleteness due to Transit Multiplicity in Kepler Planet Occurrence Rates
• The frequency of gaseous debris discs around white dwarfs
• WD 1856 b: a close giant planet around a white dwarf that could have survived a common-envelope phase
• Another one grinds the dust: Variability of the planetary debris disc at the white dwarf SDSS J104341.53+085558.2
• How Jupiters save or destroy inner Neptunes around evolved stars
• Understanding the origin of white dwarf atmospheric pollution by dynamical simulations based on detected three-planet systems
• Orbital relaxation and excitation of planets tidally interacting with white dwarfs
• Dynamical evolution of two-planet systems and its connection with white dwarf atmospheric pollution

Cited by in corpus (8)

• WD 1856 b: a close giant planet around a white dwarf that could have survived a common-envelope phase
• Accretion of tidally disrupted asteroids onto white dwarfs: direct accretion versus disk processing
• A red giant branch common envelope evolution scenario for the exoplanet WD 1856 b
• Magnetic dynamos in white dwarfs -- II. Relating magnetism and pollution
• White dwarf planetary debris dependence on physical structure distributions within asteroid belts
• Birth cluster simulations of planetary systems with multiple super-Earths: initial conditions for white dwarf pollution drivers
• Disentangling the parameter space: The role of planet multiplicity in triggering dynamical instabilities on planetary systems around white dwarfs
• Rapid expansion of red giant stars during core helium flash by waves propagation to the envelope and implications to exoplanets