Boron abundances in diffuse interstellar clouds

We present, a comprehensive survey of B abundances in diffuse interstellar clouds from HST/STIS observations along 56 Galactic sight, lines Our sample is the result of a complete search of archival STIS data for the B II lambda 1362 resonance line. with each detection confirmed by the presence of absorption from other dominant, ions at, the same velocity The data probe a range of astrophysical environments including both high-density regions of massive star formation as well as low-density paths On ought the Galactic halo, allowing us to clearly define the trend of B depletion onto interstellar grains as a function of gas density Many extended sight. lines exhibit, complex absorption profiles that, trace both local gas and gas associated with either the Sagittarius-Carma or Perseus spiral arm Our analysis indicates a higher B/O ratio in the inner Sagittarins-Carina spiral at arm than in the vicinity of the Sun, which may suggest, that, B production in the cui rent, epoch is dominated by a secondary process The average gas-phase B abundance in the warm in diffuse ISM [log c(B) = 2 38 0 10] is consistent, with the abundances damnified rot a variety of Galactic disk stars, but, is depleted by 60% relative to the solar system value Our survey also reveals sight. lines with enhanced B abundances that. potentially trace recent. production of B-11 either by cosmic-ray or neutrino-induced spallation Such sight, lines will be key to disceriting the relative importance of the two production routes rot 11B synthesis