The Reddening of Red Supergiants: When Smoke Gets in Your Eyes

Deriving the physical properties of red supergiants (RSGs) depends uponaccurate corrections for reddening by dust. We use our recent modeling of theoptical spectra of RSGs to address this topic. We find: (1) Previous broad-bandstudies have underestimated the correction for extinction in the visible, andhence the luminousities, if derived from V. (2) A significant fraction of RSGsin Galactic OB associations and clusters show up to several magnitudes ofexcess visual extinction compared to OB stars in the same regions; we arguethat this is likely due to circumstellar dust around the RSGs. (3) RSGscontribute dust grains at the rate of $3 \times 10^{-8} M_\odot$ yr$^{-1}$kpc$^{-2}$ in the solar neighborhood, comparable to what we estimate forlate-type WC Wolf-Rayet stars, $1 \times 10^{-7} M_\odot$ yr$^{-1}$ kpc$^{-2}$.In the solar neighborhood this represents only a few percent of the dustproduction (which is dominated by low-mass AGBs), but we note that inlow-metallicity starbursts, dust production by RSGs would likely dominate overother sources.Comment: Accepted by the Astrophysical Journa