Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 24 November 1995:
Vol. 270. no. 5240, pp. 1338 - 1341
DOI: 10.1126/science.270.5240.1338
Prev | Table of Contents | Next

Reports

Creation of Theta-Auroras: The Isolation of Plasma Sheet Fragments in the Polar Cap

Patrick T. Newell (1) and Ching-I. Meng

The auroral oval is a ring of luminosity enclosing geomagnetic field lines connected to the solar wind. Occasionally the ring has a bar across it, which seems to imply a bifurcation of the open region. Here results confirm that this ``-aurora'' actually does represent this odd bifurcated configuration, and they demonstrate how it happens. It has hitherto been assumed that -auroras occur when the interplanetary magnetic field is directed northward, because that is true of most very-high-latitude arcs. In fact, -auroras occur exclusively during the dynamic reconfiguration that follows when the interplanetary magnetic field turns southward after a prolonged northward interval.


Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA.
(1) To whom correspondence should be addressed.

To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)