Probing infrared excess connection with Li enhancement among red clump
  giants
  We have performed a search among low mass red giants for finding evidence for
merger scenario for triggering He-flash and subsequent Li enhancement. We chose
a sample of red giants from GALAH survey with well-measured Li abundances, and
near and mid-IR fluxes from 2MASS and WISE surveys, respectively. The sample
contains 418 cool red clump giants and 359 upper red giant branch giants. Most
of the giants and majority of super Li-rich giants show no IR excess. Only five
red clump giants and one RGB giant show IR excess. Notably, of the five red
clump giants with IR excess, three are super Li-rich (A(Li) > = 3.2 dex), and
two are Li-rich (A(Li) > = 1.0 dex). Results suggest Li enhancement among red
clump giants may be due to two channels: one resulting from in-situ He-flash in
single star evolution and the other due to He-flash triggered by events like
merger of He-white dwarfs with giants He-inert core on RGB. In the latter case,
IR excess, as a result of mass loss, is expected from merger events. We have
modelled IR excess in all six giants using DUSTY code and derived dust
parameters. The estimated kinematic ages and time scales of dust envelopes of
the super Li-rich phase suggest Li enhancement took place very recently.
Further, the analysis shows a significantly higher proportion (four out of five
red clump giants) of rapid rotators (vsini > = 8 km/s) among Li-rich giants
with IR excess compared to Li-normal and Li-rich giants with no IR excess.
