Mass Loss in Evolved Stars

Intense mass loss through cool, low-velocity winds is a defining characteristic of low-to-intermediate mass stars during the asymptotic giant branch (AGB) evolutionary stage. Such winds return up ~80% of the initial stellar mass to the interstellar medium and play a major role in enriching it with dust and heavy elements. A challenge to understanding the physics underlying AGB mass loss is its dependence on an interplay between complex and highly dynamic processes, including pulsations, convective flows, shocks, magnetic fields, and opacity changes resulting from dust and molecule formation. I highlight some examples of recent advances in our understanding of late-stage stellar mass loss that are emerging from radio and (sub)millimeter observations, with a particular focus on those that resolve the surfaces and extended atmospheres of evolved stars in space, time, and frequency.Comment: 16 pages, invited review to appear in Cosmic Masers: Proper Motion toward the Next-Generation Large Projects, IAU Symposium No. 380, T. Hirota, H. Imai, K. Menten, & Y. Pihlstrom, ed

B and V CCD Photometry of Southern, Extreme Late-Type Spiral Galaxies

We present B and V CCD aperture photometry for a morphologically-selected sample of forty-nine southern, extreme late-type spiral galaxies. All objects are moderate-to-low surface brightness Local Supercluster field galaxies that were detected previously in HI surveys. Our sample features objects that have optical luminosities, optical sizes, and HI masses which are at the low end for spiral galaxies. These objects are not a new class of galaxy, but are examples of a common type of spiral galaxy that has been under-represented in nearby galaxy samples. (Abridged).Comment: To appear in the Astronomical Journal; 31 pages + 5 tables (LaTex; uses aasms4.sty) + 10 postscript figures; .gif copies of 7 additional figure plates available via anonymous ftp at uwast.astro.wisc.edu/outgoing/jsg/papers/ELT_photom