page_title: Bipolar outflow
section_title: Galactic outflow
hierarchical_section_title: Bipolar outflow / Galactic outflow
caption_attribution_description: English: Bipolar outflow from a young star or protostar at the center of the DR 21 molecular cloud.
context_page_description: A bipolar outflow comprises two continuous flows of gas from the poles of a star. Bipolar outflows may be associated with protostars, or with evolved post-AGB stars.
context_section_description: Massive galactic molecular outflows may have the physical conditions such as high gas densities to form stars. This star-formation mode could contribute to the morphological evolution of galaxies.
caption: Infrared image of a bipolar outflow.  The outflow is driven by a massive young star that was first identified as a radio source and catalogued "DR 21". The outflow itself is known as the DR21 outflow, or MHO 898/899. Image credit: Chris Davis, UKIRT/Joint Astronomy Centre
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