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Infrared (IR) excesses around K-type red giants (RGs) have previously beendiscovered using IRAS data, and past studies have suggested a link between RGswith overabundant Li and IR excesses, implying the ejection of circumstellarshells or disks. We revisit the question of IR excesses around RGs using higherspatial resolution IR data, primarily from WISE. Our goal was to elucidate thelink between three unusual RG properties: fast rotation, enriched Li, and IRexcess. We have 316 targets thought to be K giants, about 40% of which we taketo be Li-rich. In 24 cases with previous detections of IR excess at low spatialresolution, we believe that source confusion is playing a role, in that either(a) the source that is bright in the optical is not responsible for the IRflux, or (b) there is more than one source responsible for the IR flux asmeasured in IRAS. We looked for IR excesses in the remaining sources,identifying 28 that have significant IR excesses by ~20 um (with possibleexcesses for 2 additional sources). There appears to be an intriguingcorrelation in that the largest IR excesses are all in Li-rich K giants, thoughvery few Li-rich K giants have IR excesses (large or small). These largest IRexcesses also tend to be found in the fastest rotators. There is no correlationof IR excess with the carbon isotopic ratio, 12C/13C. IR excesses by 20 um,though relatively rare, are at least twice as common among our sample ofLi-rich K giants. If dust shell production is a common by-product of Lienrichment mechanisms, these observations suggest that the IR excess stage isvery short-lived, which is supported by theoretical calculations. Conversely,the Li-enrichment mechanism may only occasionally produce dust, and anadditional parameter (e.g., rotation) may control whether or not a shell isejected.

On Infrared Excesses Associated With Li-Rich K Giants