Can solid body destruction explain abundance discrepancies in planetary nebulae?

Abstract

In planetary nebulae, abundances of oxygen and other heavy elements derived from optical recombination lines are systematically higher than those derived from collisionally excited lines. We investigate the hypothesis that the destruction of solid bodies may produce pockets of cool, high-metallicity gas that could explain these abundance discrepancies. Under the assumption of maximally efficient radiative ablation, we derive two fundamental constraints that the solid bodies must satisfy in order that their evaporation during the planetary nebula phase should generate a high enough gas phase metallicity. A local constraint implies that the bodies must be larger than tens of meters, while a global constraint implies that the total mass of the solid body reservoir must exceed a few hundredths of a solar mass. This mass greatly exceeds the mass of any population of comets or large debris particles expected to be found orbiting evolved low- to intermediate-mass stars. We therefore conclude that contemporaneous solid body destruction cannot explain the observed abundance discrepancies in planetary nebulae. However, similar arguments applied to the sublimation of solid bodies during the preceding asymptotic giant branch (AGB) phase do not lead to such a clear-cut conclusion. In this case, the required reservoir of volatile solids is only one ten-thousandth of a solar mass, which is comparable to the most massive debris disks observed around solar-type stars, implying that this mechanism may contribute to abundance discrepancies in at least some planetary nebulae, so long as mixing of the high metallicity gas is inefficient.

8 pages, no figures, ApJ in press

References in corpus (10)

• The chemical composition of the Sun
• Evolution of asymptotic giant branch stars I. Updated synthetic TP-AGB models and their basic calibration
• Debris disks around Sun-like stars
• Long-Term Collisional Evolution of Debris Disks
• On the abundance discrepancy problem in HII regions
• The History of the Solar System's Debris Disc: Observable Properties of the Kuiper Belt
• Survival of icy grains in debris discs. The role of photosputtering
• Enrichment of the ISM by metal-rich droplets and the abundance bias in HII regions
• Can X-rays provide a solution to the abundance discrepancy problem in photoionised nebulae?
• Water vapor emission from IRC+10216 and other carbon-rich stars: model predictions and prospects for multitransition observations

Cited by in corpus (13)

• Nebular spectroscopy: A guide on H II regions and planetary nebulae
• Binarity and the abundance discrepancy problem in planetary nebulae
• Analysis of chemical abundances in planetary nebulae with [WC] central stars. II. Chemical abundances and the abundance discrepancy factor
• Three-dimensional chemically homogeneous and bi-abundance photoionization models of the "super-metal-rich" planetary nebula NGC 6153
• H I Free-Bound Emission of Planetary Nebulae with Large Abundance Discrepancies: Two-Component Models versus Kappa-distributed electrons
• Photoionized Herbig-Haro objects in the Orion Nebula through deep high-spectral resolution spectroscopy I: HH529II and III
• The Discrepant Kinematics of ORLs and CELs in NGC 7009 as a Function of Ionization Structure
• The Oxygen Abundance in the Solar Neighborhood
• Studies of NGC 6720 with Calibrated HST WFC3 Emission-Line Filter Images--II:Physical Conditions
• Physical and chemical properties of Wolf-Rayet planetary nebulae
• Resonant Temperature Fluctuations in Nebulae Ionized by Short-Period Binary Stars
• Physical conditions and chemical abundances in photoionized nebulae from optical spectra
• Temperature based radial metallicity gradients in nearby galaxies