Abstract. We present intermediate results from a long-term program of mapping the neutral absorption characteristics of the local interstellar medium, motivated by the availability of accurate and consistent parallaxes from the Hipparcos satellite. Equivalent widths of the interstellar NaI D-line doublet at 5890 Å are presented for the lines-of-sight towards some 311 new target stars lying within ∼350 pc of the Sun. Using these data, together with NaI absorption measurements towards a further ∼240 nearby targets published in the literature (for many of them, in the directions of molecular clouds), and the ∼450 linesof-sight already presented by , we show 3D absorption maps of the local distribution of neutral gas towards 1005 sight-lines with Hipparcos distances as viewed from a variety of different galactic projections. The data are synthesized by means of two complementary methods, (i) by mapping of iso-equivalent width contours, and (ii) by density distribution calculation from the inversion of column-densities, a method devised by Vergely et al. (2001). Our present data confirms the view that the local cavity is deficient in cold and neutral interstellar gas. The closest dense and cold gas "wall", in the first quadrant, is at ∼55-60 pc. There are a few isolated clouds at closer distance, if the detected absorption is not produced by circumstellar material. The maps reveal narrow or wide "interstellar tunnels" which connect the Local Bubble to surrounding cavities, as predicted by the model of Cox & Smith (1974). In particular, one of these tunnels, defined by stars at 300 to 600 pc from the Sun showing negligible sodium absorption, connects the well known CMa void , which is part of the Local Bubble, with the supershell GSH 238+00+09 (Heiles 1998). High latitude lines-of-sight with the smallest absorption are found in two "chimneys", whose directions are perpendicular to the Gould belt plane. The maps show that the Local Bubble is "squeezed" by surrounding shells in a complicated pattern and suggest that its pressure is smaller than in those expanding regions. We discuss the locations of several HI and molecular clouds. Using comparisons between NaI and HI or CO velocities, in some cases we are able to improve the constraints on their distances. According to the velocity criteria, MBM 33−37, MBM 16−18, UT 3−7, and MBM 54−55 are closer than ∼100 pc, and MBM 40 is closer than 80 pc. Dense HI clouds are seen at less than 90 pc and 85 pc in the directions of the MBM 12 and MBM 41−43 clouds respectively, but the molecular clouds themselves may be far beyond. The above closest molecular clouds are located at the neutral boundary of the Bubble. Only one translucent cloud, G192−67, is clearly embedded within the LB and well isolated. These maps of the distribution of local neutral interstellar NaI gas are also briefly compared with the distribution of both interstellar dust and neutral HI gas within 300 pc.

Abstract. We present Far Ultraviolet Spectroscopic Explorer (FUSE ) observations of high-velocity gas (VLSR = +65 km s −1 ) seen towards the star HD 47240 which lies just behind the Monoceros Loop Supernova Remnant at a distance of ∼1800 pc. This high-velocity absorption feature is detected in the far ultraviolet lines of O I, Ar I, N I, C I, Fe II and P II, in addition to being detected at visible wavelengths in Na I and Ca II and at near ultraviolet wavelengths in Mg II, Mg I, S II, O I, Si II, C II*, Al II and Fe II. High-velocity interstellar gas has not been detected in the high-ionization (high-temperature) species of O VI, C IV and Si IV. Gas phase abundances relative to that of sulphur for this high velocity feature have been derived. The refractory elements of Fe, Si and Al are all less depleted than that normally found for cold disk gas in the interstellar medium, with a pattern of relative abundance more similar to that of warm interstellar disk gas. However, the elements of N, O, and Ar show an opposite pattern of relative depletion in which their apparent elemental deficiency may be attributed to ionization effects, as also found for high-velocity gas associated with the Vela SNR by Jenkins et al. (1998). The lack of detection of high-ionization gas at high velocity suggests that the Monoceros Loop remnant is more evolved than other remnants such as the Vela SNR or Cygnus Loop, and that an age of 30 000-150 000 years seems appropriate.

Abstract. We present Far Ultraviolet Spectroscopic Explorer (FUSE) satellite measurements of the absorption and emission characteristics of interstellar gas associated with the Local Interstellar Chimney, which is an extension of the rarefied Local Bubble cavity that extends outward from the galactic disk towards the lower galactic halo. Far ultraviolet (FUV) diffuse background emission has been detected in the high ionization line of O VI (λ1032 Å) for two lines-of-sight (l = 162.7• , b = +57.0 • ) and (l = 156.3• , b = +57.8• ) at emission levels of 2500 ± 700 photons cm −2 s −1 sr −1 (LU) and 3300 ± 1100 LU respectively. These levels of O VI emission are very similar to those found for four other lines-of-sight sampled thus far by the FUSE satellite, implying a fairly constant level of average O VI surface brightness emission at high galactic latitudes of about 2700 LU with a standard deviation of 450 LU. These emission-line data are supplemented by FUV interstellar absorption line measurements taken towards the hot DA white dwarf star, REJ 1032+532 (l = 157.5• , b = +53.2 • ), whose distance of 116 pc places it within the Local Bubble region. No high ionization interstellar O VI λ1032 Å absorption has been detected (N(O VI) < 13.0 cm −2 ), which is consistent with the non-detections of interstellar C IV and Si IV absorption reported towards this star by Holberg et al. (1999a). Taken together, our FUV absorption and emission data may be explained by a scenario in which the O VI emission and absorption lines are both formed at the conductive interface of the neutral boundary to the Local Bubble. For the presently sampled sight-lines we have found no correlation between the OVI emission line intensity and the associated 0.25 keV soft X-ray background flux as measured in the R1 and R2 bands by the ROSAT satellite. The OVI line intensities also show no correlation with the soft X-ray background flux attributable to emission from the million degree K gas of the Local Hot Bubble as modeled by Kuntz & Snowden (2000). Any (new) model of the Local Bubble must now be able to explain (i) the low levels of variability in both the O VI emission-line intensity and the associated soft X-ray background flux for galactic sight-lines >|40|• , (ii) the observed pressure of P/k ∼ 10 000 cm −3 K for the local hot interstellar gas, and (iii) the paucity of high ionization absorption lines observed within the local ISM and the sudden increase in their measured column density for distances beyond the Local Bubble neutral boundary.

International audienceWe present high-resolution (R= 400 000) observations of interstellar Ca ii and Na i absorption lines towards seven stars in the direction of the southern opening of the recently identified Local Interstellar Chimney. These lines of sight probe the lower Galactic halo (0.3 ≲|z|≲ 2.5 kpc), without the complication of sampling dense foreground interstellar material. In addition to components with velocities expected from Galactic rotation, these stars also exhibit components with negative local standard of rest velocities, which are contrary to the sense of Galactic rotation for the sightlines observed. After a discussion of possible origins for these peculiar velocities, we conclude that at least some of them result from gas falling towards the Galactic plane from distances of |z|≳ 300 pc. The narrow linewidths are generally inconsistent with temperatures as high as the ∼6000 K generally assumed for the so-called Lockman layer. Rather, the picture that emerges is one of a scattered, generally infalling, population of high-|z| diffuse clouds, seemingly not very different from those encountered in the local interstellar medium. Overall, we argue that our results are most consistent with a ‘Galactic fountain’ model

Abstract. We present high resolution spectra (R ∼ 5 km s −1 ) of the interstellar NaI and CaII absorption lines observed towards 9 early-type stars with distances ranging from 250 to 2300 pc in the line-of-sight towards the Cygnus Loop Supernova Remnant (SNR). All but one of these absorption profiles can be fit using a combination of one or more of three absorption components with average best-fit (lsr) velocities of V 1 = +0.8 km s −1 , V 2 = +9.0 km s −1 and V 3 = +19.7 km s −1 . An additional velocity component at V 4 = +29.7 km s −1 is required in order to fit the NaI profile recorded towards the star HD 198946, whose distance of 794 pc places it well in excess of the nominal 440 pc distance to the SNR. The NaI/CaII column density ratios for the three higher velocity components are typically <1.0, which are similar to values found for high-velocity gas components detected towards other evolved SNRs. Even though we have detected the three higher velocity components solely along the sight-lines towards stars with distance estimates greater than that of the Cygnus Loop, we are unable to definitely associate these components with an interaction between the expansion of the SN shock wave and the ambient interstellar medium. We suggest a more likely origin for these absorption components is that of an old pre-cursor SN neutral gas shell, within whose interstellar cavity the Cygnus Loop supernova explosion occured some 20 000 years ago.