transition region

noun

Astronomy.

1. a thin and very irregular layer of the sun's atmosphere that separates the hot corona from the much cooler chromosphere.

transition region

1. The area in a seed-bearing plant where the vascular tissue of the root changes into the vascular tissue of the stem. In eudicotyledons, the roots have a solid cylinder of vascular tissue surrounded by cortex. The vascular tissues gradually branch apart and reorient themselves in the stem around a central pith.

2. The thin layer of the solar atmosphere that separates the chromosphere from the corona. In the transition region, temperatures increase from a relatively cool 20,000°K in the chromosphere to the 1,000,000°K and higher temperatures of the corona. Transition region chemistry involves the ionization of hydrogen and other elements; the light produced by this region comes from ionized forms of carbon, oxygen, and silicon.

Example Sentences

And the results of Rankin and her team’s study suggest that the magnetic fields pile up less toward the heliosphere’s portside flank, meaning that a probe passing through this transition region, as opposed to the thicker draping on the other side, could more rapidly access pristine interstellar space.

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“Retrospectively it made sense that there should be a transition region where the interstellar magnetic field bunches up and drapes against the heliosphere,” says Jamie Rankin, deputy project scientist for the Voyager mission and a space physicist at Princeton University.

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“It’s going to give us a really nice ability to study what happens in this transition region—from being a frozen ice ball out in the Oort cloud to a fully active comet in the solar system.”

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By comparison, Voyager 2 did not encounter a region where the plasma stagnates, instead passing through a so-called transition region where the flow of plasma from the sun begins to change in strength and direction, followed by a “boundary layer” where incoming cosmic ray particles increase, and then a clean break through the heliopause.

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For example, the electromechanical properties of ferroelectric materials are greatly enhanced in a transition region known as a morphotropic phase boundary.

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