Asteroseismology of luminous red giants with Kepler. II. Dependence of
  mass loss on pulsations and radiation
  Mass loss by red giants is an important process to understand the final
stages of stellar evolution and the chemical enrichment of the interstellar
medium. Mass-loss rates are thought to be controlled by pulsation-enhanced
dust-driven outflows. Here we investigate the relationships between mass loss,
pulsations, and radiation, using 3213 luminous Kepler red giants and 135000
ASAS-SN semiregulars and Miras. Mass-loss rates are traced by infrared colours
using 2MASS and WISE and by observed-to-model WISE fluxes, and are also
estimated using dust mass-loss rates from literature assuming a typical
gas-to-dust mass ratio of 400. To specify the pulsations, we extract the period
and height of the highest peak in the power spectrum of oscillation. Absolute
magnitudes are obtained from the 2MASS Ks band and the Gaia DR2 parallaxes. Our
results follow. (i) Substantial mass loss sets in at pulsation periods above
~60 and ~100 days, corresponding to Asymptotic-Giant-Branch stars at the base
of the period-luminosity sequences C' and C. (ii) The mass-loss rate starts to
rapidly increase in semiregulars for which the luminosity is just above the
Red-Giant-Branch tip and gradually plateaus to a level similar to that of
Miras. (iii) The mass-loss rates in Miras do not depend on luminosity,
consistent with pulsation-enhanced dust-driven winds. (iv) The accumulated mass
loss on the Red Giant Branch consistent with asteroseismic predictions reduces
the masses of red-clump stars by 6.3%, less than the typical uncertainty on
their asteroseismic masses. Thus mass loss is currently not a limitation of
stellar age estimates for galactic archaeology studies.
