Harrison, JHD;
Bonsor, A;
Kama, M;
Buchan, AM;
Blouin, S;
Koester, D;
(2021)
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.
(In press).
Preview |
Text
stab736.pdf - Accepted Version Download (1MB) | Preview |
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.
| Type: | Article |
|---|---|
| Title: | Bayesian constraints on the origin and geology of exo-planetary material using a population of externally polluted white dwarfs |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stab736 |
| Publisher version: | https://doi.org/10.1093/mnras/stab736 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | white dwarfs, stars: abundances, planets and satellites: composition, formation, minor planets, asteroids: general, protoplanetary discs |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10125312 |
Loading...
Loading...Loading...Loading...Archive Staff Only
 |
View Item |
