Volume 546, October 2012
|Number of page(s)||12|
|Section||Interstellar and circumstellar matter|
|Published online||05 October 2012|
GS305+04-26: revisiting the interstellar medium around the Centaurus OB1 stellar association
Instituto Argentino de Radioastronomía, CCT-La Plata, CONICET,
C.C. No. 5,
2 Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina
3 Instituto de Astrofísica de La Plata, CCT-La Plata, CONICET, Argentina
Accepted: 31 July 2012
Context. Massive stars deeply modify their surrounding interstellar medium (ISM) via their high throughput of ionizing photons and their strong stellar winds. In this way, they may create large expanding structures of neutral gas.
Aims. We study a new large neutral hydrogen (Hi) shell, labelled GS305+04-26, and its relationship with the OB association Cen OB1.
Methods. To carry out this study, we have used a multi-wavelength approach. We analyse both Hi line data retrieved from the Leiden-Argentina-Bonn (LAB) survey and new spectroscopic optical observations obtained at CASLEO, as well as make use of proper motion databases available from CDS.
Results. The analysis of the Hi data reveals a large expanding structure GS305+04-26 centred at (l,b) = (305°, + 4°) in the velocity range from −33 to −17 km s-1. Based on its central velocity of −26 km s-1 and using standard galactic rotation models, a distance of 2.5 ± 0.9 kpc is inferred. This structure, elliptical in shape, has a major and minor axis of 440 and 270 pc, respectively. Its expansion velocity, total gaseous mass, and kinetic energy are ~8 km s-1, (2.4 ± 0.5) × 105 M⊙, and (1.6 ± 0.4) × 1050 erg, respectively. Several stars of the OB-association Cen OB1 are seen projected onto, and within, the boundaries of GS305+04-26. Based on an analysis of proper motions, new members of Cen OB1 are identified. The mechanical energy injected by these stars could have been the origin of this Hi structure.
Key words: Galaxy: kinematics and dynamics / Galaxy: structure / open clusters and associations: individual: Cen OB1 / ISM: bubbles / ISM: structure / radio lines: ISM
© ESO, 2012
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