Effects of Accretion Luminosity on CO and H2O Ice Lines in Protoplanetary Disks under Non-Ideal Magnetohydrodynamics: Implications for Terrestrial Planet Composition
Abstract
During Earth's formation 4 billion years ago, the Sun was 30% less luminous than it is today. Given this, our solar system's disk would be cold enough at 1AU that Earth would have formed as an ice ball in the absence of significant accretion heating. This problem is exacerbated if we consider recent work indicating that viscous heating in the midplane is significantly reduced if disk winds driven by non-ideal magnetohydrodynamics dominate observed accretion rates. Thus, to recover the fact that Earth formed as rock, there must have been an additional source of heating in the disk. We consider the luminosity from accretion at the surface of the star to increase the passive stellar irradiation temperature and find that this additional luminosity can have drastic effects on ice lines in the disk, namely the CO and water ice lines. We consider observed disks and the minimum mass solar nebula and create analytic models of the disk temperature structure where we compare heating from viscous interactions in the midplane and passive stellar irradiation with and without the surface accretion luminosity. When considering the additional heating from stellar accretion luminosity, the ice lines in the disk can be located at larger radial scales for high accretion rates: ~4AU and ~280AU for water and CO, respectively. We further discuss the implications of this result for the formation and ultimate composition of the solar system's terrestrial planets.
- Publication:
-
American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23528110S