Modelling Epsilon Aurigae without solid particles

Three components can be expected to contribute to the emission of epsilon Aurigae. There is a primary F star. There is an opaque disk which occults it, and there is a gas stream which is observed to produce absorption lines. Evidence that the disk is not responsible for the gas stream lines comes both from the radial velocities, which are too small, and from the IR energy distribution out of eclipse, which shows free-free emission that would produce inadequate optical depth in electron scattering. The color temperature of the IR excess can give misleading indications of low temperature material. Free-free emission at 10,000 K between 10 and 20 microns has a color temperature of 350 K. Attempts to mold the system are discussed

The M Dwarf Problem in the Galaxy

We present evidence that there is an M dwarf problem similar to the previously identified G dwarf and K dwarf problems: the number of low-metallicity M dwarfs is not sufficient to match simple closed-box models of local Galactic chemical evolution. We estimated the metallicity of 4141 M dwarf stars with spectra from the Sloan Digital Sky Survey (SDSS) using a molecular band strength versus metallicity calibration developed using high resolution spectra of nearby M dwarfs. Using a sample of M dwarfs with measured magnitudes, parallaxes, and metallicities, we derived a relation that describes the absolute magnitude variation as a function of metallicity. When we examined the metallicity distribution of SDSS stars, after correcting for the different volumes sampled by the magnitude-limited survey, we found that there is an M dwarf problem, with the number of M dwarfs at [Fe/H] ~ -0.5 less than 1% the number at [Fe/H] = 0, where a simple model of Galactic chemical evolution predicts a more gradual drop in star numbers with decreasing metallicity.Comment: To be published in Monthly Notices of the RAS by the Royal Astronomical Society and Blackwell Publishing. 7 pages, 3 figure