Revisiting the Impact of Dust Production from Carbon-Rich Wolf-Rayet Binaries

TL;DR

This study revisits dust production rates in carbon-rich Wolf-Rayet binaries, analyzing their contribution to galactic dust budgets through spectral energy distribution modeling and population synthesis, revealing their significant role compared to other sources.

Contribution

It provides new dust production rate estimates for WC binaries, incorporates these into population models, and compares their impact with other stellar dust sources across different metallicities.

Findings

Dust production rates in WC binaries range from 10^{-10} to 10^{-6} M_sun/yr.

A power-law relation links dust condensation fraction with orbital period and stellar wind properties.

Supernovae act as net dust destroyers across all metallicities.

Abstract

We present a dust spectral energy distribution (SED) and binary stellar population analysis revisiting the dust production rates (DPRs) in the winds of carbon-rich Wolf-Rayet (WC) binaries and their impact on galactic dust budgets. DustEM SED models of 19 Galactic WC ``dustars" reveal DPRs of $\dot{M}_d\sim10^{-10}-10^{-6}$ M$_\odot$ yr$^{-1}$ and carbon dust condensation fractions, $\chi_C$, between $0.002 - 40\%$. A large ($0.1 - 1.0$ $\mu$m) dust grain size composition is favored for efficient dustars where $\chi_C\gtrsim1\%$. Results for dustars with known orbital periods verify a power-law relation between $\chi_C$, orbital period, WC mass-loss rate, and wind velocity consistent with predictions from theoretical models of dust formation in colliding-wind binaries. We incorporated dust production into Binary Population and Spectral Synthesis (BPASS) models to analyze dust production rates from WC dustars, asymptotic giant branch stars (AGBs), red supergiants (RSGs), and core-collapse supernovae (SNe). BPASS models assuming constant star formation (SF) and a co-eval $10^6$ M$_\odot$ stellar population were performed at low, Large Magellanic Cloud (LMC)-like, and solar metallicities (Z = 0.001, 0.008, and 0.020). Both constant SF and co-eval models show that SNe are net dust destroyers at all metallicities. Constant SF models at LMC-like metallicities show that AGB stars slightly outproduce WC binaries and RSGs by factors of $2-3$, whereas at solar metallicites WC binaries are the dominant source of dust for $\sim60$ Myr until the onset of AGBs, which match the dust input of WC binaries. Co-eval population models show that for "bursty" SF, AGB stars dominate dust production at late times ($t\gtrsim 70$ Myr).