VERY DUSTY CARBON-RICH ASYMPTOTIC GIANT BRANCH STARS BETWEEN APPROXIMATELY-1 AND APPROXIMATELY-2.5 KILOPARSECS FROM THE SUN

Combining IRAS, Two Micron Sky Survey, and ground-based optical and radio data, we identify carbon-rich asymptotic giant branch (AGB) stars within ∼2.5 kpc of the Sun, in the zone 81° > δ > -33°, that are typically losing about 10-5 M⊙ yr-1. Distances are derived assuming a luminosity of 104 L⊙; there are 126 stars in this zone that are between ∼1 and ∼2.5 kpc from the Sun. By including the 29 very dusty carbon stars we previously identified to lie within 1 kpc of the Sun, we find that there is no Galactocentric gradient in the space distribution of the very dusty carbon stars in contrast to the general population of stars which is more concentrated toward the Galactic center. The surface density of very dusty carbon stars in the Galactic plane is ∼10 kpc-2. In the solar neighborhood, carbon stars return roughly half of the material from all AGB stars into the interstellar medium; in the outer Galaxy they dominate the mass return while they are probably not so important in the inner Milky Way.