Abstract Details
| Name: Bharat Kumar Yerra Affiliation: National Astronomical Observatories of China Conference ID: ASI2015_583 Title : Role of RGB Stars in Galactic Li Evolution: Connection between Li enrichment and mass-loss Authors and Co-Authors : B. E. Reddy (Indian Institute of Astrophysics), C. Muthumariappan (Indian Institute of Astrophysics), Gang Zhao (NAOC, China) Abstract Type : Oral Abstract Category : Stars, The Milky Way Galaxy and its neighbours Abstract : A small group of red giant branch (RGB) stars were found to have anomalous high Li and far-infrared excess whose origin is not well understood. Establishing the connection between these two anomalous properties in K giants is important so as to include RGB stars as one of the Li sources for the Galactic Li enrichment. Here, we have searched for a correlation between the two anomalous properties of K giants: Li enhancement and far-IR excess from an unbiased survey of a large sample (~2000) of RGB stars. Li abundances were determined from the low resolution spectra. Further, we supplemented 15 Li-rich K giants from this sample with the 25 Li-rich K giants from other studies. Dust evolutionary models and spectral energy distributions (SEDs) were constructed using the code DUSTY to estimate different dust properties such as dust evolutionary timescales, dust temperatures, mass-loss rates etc. Results show that far-IR excess similar to Li enhancement in the K giants is very uncommon, probably, due to rapid evolution of dust and Li depletion compared to RGB evolutionary time scales. We also infer from the results that during the RGB bump evolution, giants undergo some internal changes which perhaps are the cause for mass-loss and Li enhancement events. However, the available observational results do not ascertain that these properties are correlated. A few Li-rich giants with far-IR excess seems to be pure coincidence. |