TU Tau (=HD 38218 = HIP 27135) is a binary system consisting of a C-N carbon star primary and an A-type secondary. We report on new photometry and spectroscopy which tracked the recent disappearance of the A-star secondary. The dimming of the A star was gradual and irregular, with one or more brief brightenings, implying the presence of nonhomogeneities in the carbon star outflow. We also present evidence that the A star is actively accreting s -process enriched material from the carbon star and suggest that it will therefore eventually evolve into a Barium giant. This is an important system as well because the A-type star can serve as a probe of the outer atmosphere of the carbon star.

Spectroscopic observations using the classification-resolution Gray-Miller spectrograph attached to the Dark Sky Observatory 32 inch telescope (Appalachian State University, North Carolina) have been automated with a robotic script called the "Robotic Spectroscopist" (RS). RS runs autonomously during the night and controls all operations related to spectroscopic observing. At the heart of RS are a number of algorithms that first select and center the target star in the field of an imaging camera and then on the spectrograph slit. RS monitors the observatory weather station, and suspends operations and closes the dome when weather conditions warrant, and can reopen and resume observations when the weather improves. RS selects targets from a list using a queue-observing protocol based on observer-assigned priorities, but also uses target-selection criteria based on weather conditions, especially seeing. At the end of the night RS transfers the data files to the main campus, where they are reduced with an automatic pipeline. Our experience has shown that RS is more efficient and consistent than a human observer, and produces data sets that are ideal for automatic reduction. RS should be adaptable for use at other similar observatories, and so we are making the code freely available to the astronomical community.

Barium ii (Ba) stars are chemically peculiar F-, G-, and K-type objects that show enhanced abundances of s-process elements. Since s-process nucleosynthesis is unlikely to take place in stars prior to the advanced asymptotic giant branch (AGB) stage, the prevailing hypothesis is that each present Ba star was contaminated by an AGB companion which is now a white dwarf (WD). Unless the initial mass ratio of such a binary was fairly close to unity, the receiving star is thus at least as likely to be a dwarf as a giant. So although most known Ba stars appear to be giants, the hypothesis requires that Ba dwarfs be comparably plentiful and moreover that they should all have WD companions. However, despite dedicated searches with the IUE satellite, no WD companions have been directly detected to date among the classical Ba dwarfs, even though some 90% of those stars are spectroscopic binaries, so the contamination hypothesis is therefore presently in some jeopardy. In this paper, we analyze recent deep, near-UV and far-UV Galaxy Evolution Explorer (GALEX) exposures of four of the brightest of the class (HD 2454, 15360, 26367, and 221531), together with archived GALEX data for two newly recognized Ba dwarfs: HD 34654 and HD 114520 (which also prove to be spectroscopic binaries). The GALEX observations of the Ba dwarfs as a group show a significant far-UV excess compared to a control sample of normal F-type dwarfs. We suggest that this ensemble far-UV excess constitutes the first direct evidence that Ba dwarfs have WD companions.