The Very Slow Wind from the Pulsating Semiregular Red Giant, L2 Pup

We have obtained 11.7 μm and 17.9 μm images at the Keck I telescope of the circumstellar dust emission from L2 Pup, one of the nearest (D = 61 pc) masslosing, pulsating, red giants that has a substantial infrared excess. We propose that the star is losing mass at a rate of ∼3 × 10 M⊙ yr . Given its relatively low luminosity (∼ 1500 L⊙), relatively high effective temperature (near 3400 K), relatively short period (∼ 140 days), and the inferred gas outflow speed of 3.5 km s, standard models for dust-driven mass loss do not apply. Instead, the wind may be driven by the stellar pulsations with radiation pressure on dust being relatively unimportant, as described in some recent calculations. L2 Pup may serve as the prototype of this phase of stellar evolution where it could lose ∼15% of its initial main sequence mass. Subject headings: circumstellar matter –stars: mass loss