Stars, Gas, and Dark Matter in the Solar Neighborhood

We reanalyze data on the surface densities and vertical distribution of baryonic matter in the solar neighborhood and tabulate the results. We find a local total surface density of M dwarfs of 17.3 +/- 2.3 M-circle dot pc(-2), whcih is significantly higher than previous values. Our result for the total local surface density of visible stars (main-sequence stars and giants), 27.0 +/- 2.7 M-circle dot pc(-2), is close to previous estimates due to a cancellation of opposing effects: more mass in M dwarfs, less mass in the others. The total local surface density in white dwarfs is 4.9 +/- 0.6 M-circle dot pc(-2); in brown dwarfs, it is similar to 1.2 M-circle dot pc(-2), but with considerable uncertainty. We find that the total local surface density of stars and stellar remnants is 33.4 +/- 3 M-circle dot pc(-2), which is somewhat less than previous estimates but within the errors of many of them. We analyze data on 21 cm emission and absorption and obtain good agreement with recent results on the local amount of neutral atomic hydrogen obtained with the Planck satellite. The local surface density of gas is 13.7 +/- 1.6 M-circle dot pc(-2). The total baryonic mass surface density that we derive for the solar neighborhood is 47.1 +/- 3.4 M-circle dot pc(-2) (43.8 M-circle dot pc(-2). within 1.1 kpc of the midplane). Combining these results with others' measurements of the total surface density of matter within 1-1.1 kpc of the plane, we find that the local density of dark matter is rho(DM) = 0.013 +/- 0.003 M-circle dot pc(-3) = 0.49 +/- 0.13 GeV cm(-3). The local density of all matter is 0.097 +/- 0.013 M pc(-3). We discuss limitations on the properties of a possible thin disk of dark matter.