Constraining dust properties in Circumstellar Envelopes of C-stars in the Small Magellanic Cloud: optical constants and grain size of Carbon dust

Abstract

We present a new approach aimed at constraining the typical size and optical properties of carbon dust grains in Circumstellar envelopes (CSEs) of carbon-rich stars (C-stars) in the Small Magellanic Cloud (SMC). To achieve this goal, we apply our recent dust growth description, coupled with a radiative transfer code to the CSEs of C-stars evolving along the TP-AGB, for which we compute spectra and colors. Then we compare our modeled colors in the near- and mid-infrared (NIR and MIR) bands with the observed ones, testing different assumptions in our dust scheme and employing several data sets of optical constants for carbon dust available in the literature. Different assumptions adopted in our dust scheme change the typical size of the carbon grains produced. We constrain carbon dust properties by selecting the combination of grain size and optical constants which best reproduces several colors in the NIR and MIR at the same time. The different choices of optical properties and grain size lead to differences in the NIR and MIR colors greater than two magnitudes in some cases. We conclude that the complete set of observed NIR and MIR colors are best reproduced by small grains, with sizes between $\sim$0.035 and $\sim$0.12~$\mu$m, rather than by large grains between $\sim 0.2$ and $0.7$~$\mu$m. The inability of large grains to reproduce NIR and MIR colors seems independent of the adopted optical data set. We also find a possible trend of the grain size with mass-loss and/or carbon excess in the CSEs of these stars.

23 pages, 22 fugures

References in corpus (6)

• Evolution of asymptotic giant branch stars I. Updated synthetic TP-AGB models and their basic calibration
• Evolution of interstellar dust and stardust in the solar neighbourhood
• AGB stars in the Magellanic Clouds. II. The rate of star formation across the LMC
• Molecules and dust production in the Magellanic Clouds
• Evolution of Thermally Pulsing Asymptotic Giant Branch Stars IV. Constraining Mass-Loss & Lifetimes of Low Mass, Low Metallicity AGB Stars
• Estimating the dust production rate of carbon stars in the Small Magellanic Cloud

Cited by in corpus (23)

• Luminosities and mass-loss rates of Local Group AGB stars and Red Supergiants
• The mass-loss, expansion velocities and dust production rates of carbon stars in the Magellanic Clouds
• Estimating the dust production rate of carbon stars in the Small Magellanic Cloud
• An Infrared Census of DUST in Nearby Galaxies with Spitzer (DUSTiNGS). IV. Discovery of High-Redshift AGB Analogs
• Carbon star wind models at solar and sub-solar metallicities: a comparative study. I. Mass loss and the properties of dust-driven winds
• The evolution of Galactic planetary nebula progenitors through the comparison of their nebular abundances with AGB yields
• Understanding the evolution and dust formation of carbon stars in the LMC with a look at the JWST
• AGB dust and gas ejecta in extremely metal-poor environments
• A Dramatic Decrease in Carbon Star Formation in M31
• On the mass and metallicity distribution of parent AGB stars of presolar SiC
• New Post-AGB star models as tools to understand AGB evolution and nucleosynthesis
• A Remarkable Oxygen-rich Asymptotic Giant Branch Variable in the Sagittarius Dwarf Irregular Galaxy
• Carbon stars with increased oxygen and nitrogen abundances: hydrostatic dust-free model atmospheres
• The intense production of silicates during the final AGB phases of intermediate mass stars
• Dust formation and mass loss around intermediate-mass AGB stars with initial metallicity $Z_{\mathrm{ini}}\le 10^{-4}$ in the early Universe I: Effect of surface opacity on the stellar evolution and dust-driven wind
• A study of oxygen-rich post-AGB stars in the Milky Way to understand the production of silicates from evolved stars
• Asymptotic Giant Branch Stars in the Nearby Dwarf Galaxy Leo P
• The impact of third dredge-up on the mass loss of Mira variables
• Extended view on the dust shells around two carbon stars
• Dynamic atmosphere and wind models of C-type asymptotic giant branch stars. Influences of dust optical data on mass loss and observables
• Charting circumstellar chemistry of carbon-rich asymptotic giant branch stars. II. Abundances and spatial distributions of CS
• Gas and dust from extremely metal-poor AGB stars
• Dust Production around Carbon-Rich Stars: The Role of Metallicity