The interstellar medium surrounding the Scorpius-Centaurus association revisited

Abstract

Aims. We want to make a large-scale study of the morphology, kinematics, and origin of the H I, which surrounds the Sco-Cen association. Methods. We combine our high-sensitivity southern H I survey with the Leiden/Dwingeloo Survey, considering l = 240 • −400 • , b = −60 • to +60 • , and radial velocities of V = −41.8 to +40.8 km s −1 . We point out the main H I branches surrounding the association and derive their kinematics. Kinematical H I-maps were compared with spatial maps of interstellar (IS) Na I from the literature. Upper limits for distances d were derived from optical IS absorption components from the literature. Models of expanding spherical H I shells were fitted around each stellar subgroup. Results. The expanding ring of H I associated with the Gould Belt (GB) is very prominent. At each l, its radial velocity shifts ∼−7 km s −1 within an interval Δb ∼ 10 • −25 • . On the sky, the shifts occur within a narrow stripe extending between l, b ∼ 250 • , −18 • and 400 • , +50 • . The ranges of distances and radial thicknesses of most H I branches are nearly 70−160 pc and 40−90 pc, respectively. The shell-models fit the main branches. Interactions between the shells built a large expanding bubble with a transverse diameter of nearly 250 pc around the association. The near face is approaching with a mean velocityV ∼ −6.6 km s −1 at d ≤ 76 pc from the Sun, covering about 102 • × 65 • (l, b), forming an "H I-wall". There are streamers atV ∼ −15 to −35 km s −1 , as well as gas presumably overshot into Galactic Quadrant II. The receding gas is more tenuous. Conclusions. The association is traversing the ring since a time comparable to its age producing a significant disturbance on the expanding GB-ring of gas. The latter was almost totally shocked by the association, northerly of the stripe of velocity shifts. Southerly there are large amounts of preshocked gas, as well as smaller more localized shocked regions. Hot gas within the bubble produces most of the 1/4 keV radiation detected toward it by ROSAT. The total mass of the GB gas embedding the Sco-Cen association is estimated at M t ∼ 368 000 M ± 60%, including ∼34 000 M of associated H 2 and 30% of He. About 39% of the embedding gas was shocked by the association. At | b |≥ 35 • , a comparison of the observations with test points moving on ballistic orbits is consistent with the formation of the Sco-Cen association within the gas ring of the GB and the presumable explosive origin of the latter. The rotation of the ring is assumed.

3D maps of the local ISM from inversion of individual color excess measurements

“…This is especially mandatory for the dense atomic and molecular phase. This should help for understanding the complex kinematical structure of the whole Sco-Cen area recently derived by Pöppel et al (2010) based on HI 21 cm data from the Leiden-Dwingeloo Survey and its link with the Gould belt formation. Present or future surveys and especially the Gaia mission should help improving the mapping.…”

Squeezed between shells? The origin of the Lupus I molecular cloud

“…In addition we used Na I absorption data in the foreground of stars with known distances from Hipparcos measurements, using the same shell model as for the HI data. This follows an analysis approach presented elsewhere (Pöppel et al 2010;Welsh et al 2010). The parameters of our expanding-shell model are distance to the center of the shell D 0 ; Notes.…”

26Al kinematics: superbubbles following the spiral arms?

“…They found porosities higher than unity inside of the solar circle, and thus strong overlap of superbubbles. The closest massive star group, Scorpius-Centaurus OB2, is an excellent example for superbubble merging (Pöppel et al 2010;Preibisch & Mamajek 2008): the different subgroups of the OB association appear to have been triggered by expanding shells from the older Notes. For each entry, the first (second) number is for random sampling (truncated IMFs).…”