Exploring Mass-Loss in M-type AGB Stars
2015 (English)In: WHY GALAXIES CARE ABOUT AGB STARS III: A CLOSER LOOK IN SPACE AND TIME, ASTRONOMICAL SOC PACIFIC , 2015, Vol. 497, 345-350 p.Conference paper (Refereed)Text
Stellar winds observed in asymptotic giant branch (AGB) stars are usually attributed to a combination of stellar pulsations and radiation pressure on dust. Strong candidates for wind-driving dust species in M-type AGB stars are magnesium silicates (Mg2SiO4 and MgSiO3). Such grains can form close to the stellar surface; they consist of abundant materials and, if they grow to sizes comparable to the wavelength of the stellar flux maximum, they experience strong acceleration by photon scattering. Here we present results from an extensive set of time-dependent wind models for M-type AGB stars with a detailed description for the growth of Mg2SiO4 grains. We show that these models reproduce observed mass-loss rates and wind velocities, as well as visual and near-IR photometry. However, the current models do not show the characteristic silicate features at 10 and 18 mu m, due to a rapidly falling temperature of Mg2SiO4 grains in the wind. Including a small amount of Fe in the grains further out in the circumstellar envelope will increase the grain temperature and result in pronounced silicate features, without significantly affecting the photometry in the visual and near-IR.
Place, publisher, year, edition, pages
ASTRONOMICAL SOC PACIFIC , 2015. Vol. 497, 345-350 p.
Fusion, Plasma and Space Physics
IdentifiersURN: urn:nbn:se:uu:diva-294842ISI: 000371098100068OAI: oai:DiVA.org:uu-294842DiVA: diva2:931435
Conference on Why Galaxies Care About AGB Stars III: A Closer Look in Space and Time, JUL 28-AUG 01 2014, Univ Vienna, Vienna, AUSTRIA