Interstellar polarization and extinction in the Local Bubble and the Gould Belt

Abstract

We analyse an all-sky compilation of 13 data sources with optical interstellar linear polarization for 3871 Gaia DR2 and Hipparcos stars within 500 pc, which do not exhibit a considerable intrinsic polarization. These data are analysed together with five 3D maps and models of the reddening E(B - V). We consider variations of the polarization degree P, position angle θ, and polarization efficiency P/E(B - V) with Galactic coordinates, distance R, and dereddened colour. P shows a maximum at the Gould Belt mid-plane. P/R drops in the Local Bubble by several times defining a boundary of the Bubble at P = 0.1 per cent. All the data sources of the reddening, except Lallement et al., show a drop of P/E(B - V) in the Bubble. A significant number of stars with a too high P/E(B - V), where the reddening is taken from Arenou et al., Drimmel et al. or Lallement et al., either reject the Serkowski's limit P/E(B - V) < 9.3 per cent per mag or manifest a systematic underestimation of the reddening by these data sources. The spatial- and colour-dependent variations of P and E(B - V) outside the Bubble compensate each other, resulting in a nearly constant P/E(B - V). A giant envelope of aligned dust dominates at middle and high latitudes outside the Bubble. The Markkanen's cloud, the North Polar Spur, and some other filaments are parts of this envelope.