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Polluting white dwarfs with Oort cloud comets
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DOI：10.1093/mnras/stae986.png)
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Abstract
En 中文
Observations point to old white dwarfs (WDs) accreting metals at a relatively constant rate over 8 Gyr. Exo-Oort clouds around WDs have been proposed as potential reservoirs of materials, with galactic tide as a mechanism to deliver distant comets to the WD's Roche limit. In this work, we characterize the dynamics of comets around a WD with a companion having semimajor axes on the orders of 10-100 au. We develop simulation techniques capable of integrating a large number (108) of objects over a 1 Gyr time-scale. Our simulations include galactic tide and are capable of resolving close interactions with a massive companion. Through simulations, we study the accretion rate of exo-Oort cloud comets into a WD's Roche limit. We also characterize the dynamics of precession and scattering induced on a comet by a massive companion. We find that (i) WD pollution by an exo-Oort cloud can be sustained over a Gyr time-scale, (ii) an exo-Oort cloud with structure like our own Solar system's is capable of delivering materials into an isolated WD with pollution rate similar to 10(8) g s(-1), (iii) adding a planetary-mass companion reduces the pollution rate to similar to 10(7) g s(-1), and (iv) if the companion is stellar mass, with M-p greater than or similar to 0.1 M-circle dot, the pollution rate reduces to similar to 3 x 10(5) g s(-1 )due to a combination of precession induced on a comet by the companion, a strong scattering barrier, and low likelihood of direct collisions of comets with the companion.
Keywords:
comets: general
Oort Cloud
white dwarfs
planets and satellites: dynamical evolution and stability
Journal
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4.8
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7.1W
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25.0W
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