v 1 2 J an 2 00 2 SiO chimneys and supershells in M 82 1 S . Garćıa - Burillo J . Mart́ın - Pintado A . Fuente
نویسندگان
چکیده
In this letter we present the first images of the emission of SiO and H 13 CO + in the nucleus of the starburst galaxy M 82. Contrary to other molecular species, which mainly trace the distribution of the star forming molecular gas within the disk, the SiO emission extends noticeably out of the galaxy plane. The bulk of the SiO emission is restricted to two major features. The first feature, referred to as the SiO supershell, is an open shell of 150 pc diameter, located 120 pc west from the galaxy center. The SiO supershell represents the inner front of a molecular shell expanding at ∼40 kms −1 , produced by mass ejection around a supercluster of young stars containing SNR 41.95+57.5. The second feature is a vertical filament, referred to as the SiO chimney, emanating from the disk at 200 pc east from the galaxy center. The SiO chimney reaches a 500 pc vertical height and it is associated with the most prominent chimney identified in radiocontinuum maps. The kinematics, morphology, and fractional abundances of the SiO gas features in M 82 can be explained in the framework of shocked chemistry driven by local episodes of gas ejection from the starburst disk. The SiO emission stands out as a privileged tracer of the disk-halo interface in M 82. We speculate that the chimney and the supershell, each injecting ∼10 7 M ⊙ of molecular gas, are two different evolutionary stages in the outflow phenomenon building up the gaseous halo.
منابع مشابه
Large - scale shocks in the starburst galaxy NGC 253 Interferometer mapping of a ∼ 600 pc SiO / H 13 CO + circumnuclear disk
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