Issue |
A&A
Volume 512, March-April 2010
|
|
---|---|---|
Article Number | A83 | |
Number of page(s) | 26 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/200811290 | |
Published online | 09 April 2010 |
The interstellar medium surrounding the Scorpius-Centaurus association revisited*
1
Instituto Argentino de Radioastronomía (CCT La Plata – CONICET), C.C. No. 5, 1894 Villa Elisa, B.A.,
Argentina e-mail: wpoppel@iar.unlp.edu.ar
2
Facultad de Ciencias Astronómicas y Geofísicas
Universidad Nacional de La Plata, Paseo del Bosque s/n,
1900 La Plata, Argentina
Received:
4
November
2008
Accepted:
4
September
2009
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 velocity
~ -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 at
~ -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 Mt ~ 368 000 ± 60%,
including ~34 000
of associated H2 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.
Key words: open clusters and associations: individual: Sco-Cen association / open clusters and associations: individual: Gould Belt / ISM: clouds /
Appendix is only available in electronic form at http://www.aanda.org
© ESO, 2010
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.