bipolar outflow


Also found in: Wikipedia.

bipolar outflow

A flow of gas from a very young star, forming two oppositely directed beams; it is apparently a common feature of star formation. In the youngest stars the bipolar flow is detected by the radio emission from molecules such as carbon monoxide; when stars have dispersed most of the surrounding gas and dust, the outflow is visible optically as a bipolar nebula or as ‘jets' extending away from a T Tauri star for thousands of astronomical units. Both kinds of outflow can reach speeds of several hundred kilometers per second. The outflow from T Tauri stars can produce a line of Herbig–Haro objects. These flows are too powerful to be driven by the pressure of the star's radiation. They are probably T Tauri winds that are channeled outward from the star's poles, a disk of dense gas around the equator preventing them from escaping isotropically. Such disks are indeed often detected in the centers of the different kinds of bipolar outflow at the correct orientation to account for the observed outflow of less-dense gas.
References in periodicals archive ?
The professional literature reveals NGC 6751 to be a highly structured, multiple-shell planetary with a bipolar outflow. Well-known observer Steve Coe proclaims it to be one of the best objects in Aquila, and many would agree.
(https://www.nature.com/articles/s41550-017-0146) The paper published by the researchers is titled "Disk-driven rotating bipolar outflow in Orion Source I." It said the outflow and jets from the protostar travel to a distance of over 10 AU (1 AU is the distance between Earth and the sun), at a speed of about 10 kilometers (6.2 miles) per second.
Looking at the star using NASA's Hubble Space Telescope, astronomers had expected to see a bipolar outflow of twin lobes of gas from the star.
Over the last 1,500 years, nearly one and a half times the mass of our Sun has been lost by the central star of the Boomerang Nebula in an ejection process known as a bipolar outflow. The nebula's name is derived from its symmetric structure as seen from ground-based telescopes.
The new research focuses on HH 46/47, the bipolar outflow from a protostar forming on the outskirts of the Gum Nebula, at about 1,400 light-years away.
Mapping the carbon monoxide, he found that the infrared source is the center of a bipolar outflow of matter amounting to something between 1 and 10 times the mass of the sun per year.
When the star later expels a fast wind, the wind rams into and is funneled by the older material, creating a bipolar outflow.
The present project brings together the expertise of two research groups at MPIfR, infrared interferometry in order to investigate the structure of the disk and submillimeter astronomy showing the structure of the bipolar outflow," he added.
t does so by spewing material in opposite directions as a bipolar outflow.
Bipolar outflow results when the rotating disks that surround developing new stars jet gas from their polar regions, which astronomers have observed telescopically.
At the same time, strong winds lift off from the inner disk regions and form a bipolar outflow that burrows through the surrounding dark cloud, thus forming two large outflow cavities.
It ejects two streams of plasma in a bipolar outflow at velocities of several hundred kilometers per second.