scholarly journals Host-star and exoplanet compositions: a pilot study using a wide binary with a polluted white dwarf

2021 ◽  
Vol 503 (2) ◽  
pp. 1877-1883
Author(s):  
Amy Bonsor ◽  
Paula Jofré ◽  
Oliver Shorttle ◽  
Laura K Rogers ◽  
Siyi Xu(许偲艺) ◽  
...  
Keyword(s):  
White Dwarf ◽  
Planetary System ◽  
Kuiper Belt ◽  
Wide Binary ◽  
Elemental Abundances ◽  
Exoplanetary Systems ◽  
Planetary Bodies ◽  
Refractory Composition ◽  
Observational Errors ◽  
Host Stars

ABSTRACT Planets and stars ultimately form out of the collapse of the same cloud of gas. Whilst planets, and planetary bodies, readily loose volatiles, a common hypothesis is that they retain the same refractory composition as their host star. This is true within the Solar system. The refractory composition of chondritic meteorites, Earth, and other rocky planetary bodies are consistent with solar, within the observational errors. This work aims to investigate whether this hypothesis holds for exoplanetary systems. If true, the internal structure of observed rocky exoplanets can be better constrained using their host star abundances. In this paper, we analyse the abundances of the K-dwarf, G200-40, and compare them to its polluted white dwarf companion, WD 1425+540. The white dwarf has accreted planetary material, most probably a Kuiper belt-like object, from an outer planetary system surviving the star’s evolution to the white dwarf phase. Given that binary pairs are chemically homogeneous, we use the binary companion, G200-40, as a proxy for the composition of the progenitor to WD 1425+540. We show that the elemental abundances of the companion star and the planetary material accreted by WD 1425+540 are consistent with the hypothesis that planet and host-stars have the same true abundances, taking into account the observational errors.

scholarly journals A numerical method for computing optimum radii of host stars and orbits of planets, with application to Kepler-11, Kepler-90, Kepler-215, HD 10180, HD 34445 and TRAPPIST-1

2020 ◽  
pp. 2150028
Author(s):  
V. S. Geroyannis
Keyword(s):  
Numerical Method ◽  
Planetary System ◽  
Hydrostatic Equilibrium ◽  
Polytropic Index ◽  
Spherical Shells ◽  
Polytropic Model ◽  
Emden Equation ◽  
Exoplanetary Systems ◽  
Planetary Orbits ◽  
Host Stars

In the so-called “global polytropic model”, we assume planetary systems in hydrostatic equilibrium and solve the Lane–Emden equation in the complex plane. We thus find polytropic spherical shells providing accommodation to planetary orbits. On the basis of this model, we develop a numerical method which can compute optimum values for the polytropic index of the global polytropic model that simulates the planetary system, for the orbits of the planets, and for the host star radius. We apply our method to the exoplanetary systems Kepler-11, Kepler-90, Kepler-215, HD 10180, HD 34445 and TRAPPIST-1.

scholarly journals Lithium pollution of a white dwarf records the accretion of an extrasolar planetesimal

Science ◽  
2020 ◽  
Vol 371 (6525) ◽  
pp. 168-172
Author(s):  
B. C. Kaiser ◽  
J. C. Clemens ◽  
S. Blouin ◽  
P. Dufour ◽  
R. J. Hegedus ◽  
...  
Keyword(s):  
Solar System ◽  
White Dwarf ◽  
Big Bang ◽  
Early Solar System ◽  
Big Bang Nucleosynthesis ◽  
Lithium Abundance ◽  
Sodium Potassium ◽  
Elemental Abundances ◽  
Exoplanetary Systems ◽  
Gaia Dr2

Tidal disruption and subsequent accretion of planetesimals by white dwarfs can reveal the elemental abundances of rocky bodies in exoplanetary systems. Those abundances provide information on the composition of the nebula from which the systems formed, which is analogous to how meteorite abundances inform our understanding of the early Solar System. We report the detection of lithium, sodium, potassium, and calcium in the atmosphere of the white dwarf Gaia DR2 4353607450860305024, which we ascribe to the accretion of a planetesimal. Using model atmospheres, we determine abundance ratios of these elements, and, with the exception of lithium, they are consistent with meteoritic values in the Solar System. We compare the measured lithium abundance with measurements in old stars and with expectations from Big Bang nucleosynthesis.

scholarly journals Exogeology from Polluted White Dwarfs

Elements ◽  
2021 ◽  
Vol 17 (4) ◽  
pp. 241-244
Author(s):  
Siyi Xu ◽  
Amy Bonsor
Keyword(s):  
Solar System ◽  
White Dwarf ◽  
White Dwarfs ◽  
Planetary Systems ◽  
Terrestrial Planets ◽  
Strong Gravity ◽  
Exoplanetary Systems ◽  
Planetary Bodies

It is difficult to study the interiors of terrestrial planets in the Solar System and the problem is magnified for distant exoplanets. However, sometimes nature is helpful. Some planetary bodies are torn to fragments and consumed by the strong gravity close to the descendants of Sun-like stars, white dwarfs. We can deduce the general composition of the planet when we observe the spectroscopic signature of the white dwarf. Most planetary fragments that fall into white dwarfs appear to be rocky with a variable fraction of associated ice and carbon. These white dwarf planetary systems provide a unique opportunity to study the geology of exoplanetary systems.

The evolution of the Kuiper belt during the formation of the outer planets

1999 ◽  
Vol 173 ◽  
pp. 37-44
Author(s):  
M.D. Melita ◽  
A. Brunini
Keyword(s):  
Kuiper Belt ◽  
Outer Planets ◽  
Self Consistent ◽  
Planetary Bodies ◽  
Mass Depletion

AbstractA self-consistent study of the formation of planetary bodies beyond the orbit of Saturn and the evolution of Kuiper disks is carried out by means of an N-body code where accretion and gravitational encounters are considered. This investigation is focused on the aggregation of massive bodies in the outer planetary region and on the consequences of such process in the corresponding cometary belt. We study the link between the bombardment of massive bodies and mass depletion and eccentricity excitation.

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

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.

scholarly journals On the alignment of debris discs and their host stars’ rotation axis - implications for spin-orbit misalignment in exoplanetary systems

2011 ◽  
Vol 413 (1) ◽  
pp. L71-L75 ◽  
Author(s):  
C. A. Watson ◽  
S. P. Littlefair ◽  
C. Diamond ◽  
A. Collier Cameron ◽  
A. Fitzsimmons ◽  
...  
Keyword(s):  
Rotation Axis ◽  
Spin Orbit ◽  
Exoplanetary Systems ◽  
Host Stars

scholarly journals The relation between white dwarf mass and orbital period in wide binary radio pulsars

1995 ◽  
Vol 273 (3) ◽  
pp. 731-741 ◽  
Author(s):  
S. Rappaport ◽  
Ph. Podsiadlowski ◽  
P. C. Joss ◽  
R. Di Stefano ◽  
Z. Han
Keyword(s):  
Orbital Period ◽  
White Dwarf ◽  
Radio Pulsars ◽  
Wide Binary

scholarly journals Planetary architectures in interacting stellar environments

2020 ◽  
Vol 496 (2) ◽  
pp. 1453-1470 ◽  
Author(s):  
Yi-Han Wang ◽  
Rosalba Perna ◽  
Nathan W C Leigh
Keyword(s):  
High Resolution ◽  
Cross Section ◽  
Cross Sections ◽  
Velocity Dispersion ◽  
Planetary System ◽  
Star Clusters ◽  
Exoplanetary Systems ◽  
The Cross ◽  
Star Binary ◽  
Strong Scattering

ABSTRACT The discovery of exoplanetary systems has challenged some of the theories of planet formation, which assume unperturbed evolution of the host star and its planets. However, in star clusters the interactions with fly-by stars and binaries may be relatively common during the lifetime of a planetary system. Here, via high-resolution N-body simulations of star–planet systems perturbed by interlopers (stars and binaries), we explore the reconfiguration to the planetary system due to the encounters. In particular, via an exploration focused on the strong scattering regime, we derive the fraction of encounters that result in planet ejections, planet transfers, and collisions by the interloper star/binary, as a function of the characteristics of the environment (density, velocity dispersion), and for different masses of the fly-by star/binary. We find that binary interlopers can significantly increase the cross-section of planet ejections and collisions, while they only slightly change the cross-section for planet transfers. Therefore, in environments with high binary fractions, floating planets are expected to be relatively common, while in environments with low binary fractions, where the cross-sections of planet ejection and transfer are comparable, the rate of planet exchanges between two stars will be comparable to the rate of production of free-floating planets.

scholarly journals Different types of star-planet interactions

2019 ◽  
Vol 15 (S354) ◽  
pp. 259-267
Author(s):  
A. A. Vidotto
Keyword(s):  
Physical Characteristics ◽  
Electromagnetic Spectrum ◽  
Exoplanetary Systems ◽  
Different Types ◽  
Host Stars

AbstractStars and their exoplanets evolve together. Depending on the physical characteristics of these systems, such as age, orbital distance and activity of the host stars, certain types of star-exoplanet interactions can dominate during given phases of the evolution. Identifying observable signatures of such interactions can provide additional avenues for characterising exoplanetary systems. Here, I review some recent works on star-planet interactions and discuss their observability at different wavelengths across the electromagnetic spectrum.

scholarly journals White Dwarfs in Cataclysmic Binaries

1979 ◽  
Vol 53 ◽  
pp. 417-425 ◽  
Author(s):  
Brian Warner
Keyword(s):  
Direct Measurement ◽  
White Dwarf ◽  
Proper Motion ◽  
White Dwarfs ◽  
Binary Systems ◽  
Fundamental Property ◽  
Wide Binary ◽  
Trigonometric Parallax ◽  
Select Group ◽  
Cataclysmic Binaries

For isolated stars, identification as a white dwarf may be effected in several ways. The fundamental property of abnormally low luminosity can be detected through direct measurement of trigonometric parallax or indirectly through large proper motion (accompanied by appropriate photometric properties). The presence of greatly pressure broadened absorption lines is another unambiguous criterion. Rapid light oscillations of the kind reviewed by Robinson are another hallmark of a select group of white dwarfs. Any or all of these criteria may be used to classify a star as a white dwarf and in general can be applied to members of wide binary systems.

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