SciVerse Home ScienceDirect® Home * Hub * ScienceDirect * Scopus * Applications * Register * Login * Go to SciVal Suite Username: Password: Remember me | Not Registered? Forgotten your username or password? Go to Athens / Institution login You have guest access to ScienceDirect. Find out more. * Home * Browse * Search * My settings * My alerts * Help All fields Author Advanced search Journal/Book title Volume Issue Page Search tips Advertisement Font Size: Decrease Font Size Increase Font Size Related Articles Currents in the cometary atmosphere /Planetary and Space Science/ Close You are not entitled to access the full text of this document *Currents in the cometary atmosphere Original Research Article* /Planetary and Space Science/, /Volume 27, Issue 2/, /February 1979/, /Pages 121-125/ W.-H. Ip *Abstract* If the structure of the magnetic field and electric current in the cometary type I tail can be represented by an electric current circuit, disruption of the cross-tail current system may lead to a current discharging through the cometary ionosphere, and the dissipation of the magnetic energy stored in the tail. From the point of view of energy budget, a tail-aligned magnetic field on the order of 10γ will be sufficient to produce a strong ionization effect of the cometary atmosphere. Purchase PDF (500 K) Structures far from the head of comet Kohoutek : II. A ... /Icarus/ Close You are not entitled to access the full text of this document *Structures far from the head of comet Kohoutek : II. A discussion of the swan cloud of January 11 and of the general morphology of cometary plasma tails Original Research Article* /Icarus/, /Volume 42, Issue 2/, /May 1980/, /Pages 257-270/ Malcolm B. Niedner Jr., John C. Brandt *Abstract* Photographs taken in New Mexico and in Japan during 1974 January 9–11 show that the “Swan Cloud” observed in comet Kohoutek on January 11 ([Hyder et al., 1974], Icarus23, 601–610: Paper I) was an advanced stage of a plasma tail disconnection event (DE). The event commenced and evolved with the development of strong tail ray activity, the actual tail disconnection, the merging of the disconnected tail with the new tail to form the Swan, and a new feature not discussed in recent disconnection models—the formation of arcade loops in the space between closing tail rays. An unusual aspect of the event was the deceleration of the rejected tail as it receded from the head. The observed morphological sequence is easily understood in the sector boundary model ([Niedner and Brandt, 1978], Astrophys. J.223, 655–670; 1979, Astrophys. J.234 723–732), in which dayside reconnection of captured interplanetary fields at sector boundary crossings strips away the existing tail, and field capture in the new sector builds a new tail. The associated sector boundary for the event passed Earth of 1974 January 14. The arcade loops are proposed to be reconnected flux tubes between oppositely polarized tail rays in the incipient new tail which followed the disconnection. This interpretation is not only consistent with the magnetic field topology advocated in Alfvén's original model (H. Alfvén, 1957 Tellus9 92–96), but it may also provide a physical model for some of the features known historically as “condensation,” at least some of which appear to have formed in the same manner. Purchase PDF (8578 K) Dynamics of cometary plasma tails /Advances in Space Research/ Close You are not entitled to access the full text of this document *Dynamics of cometary plasma tails Original Research Article* /Advances in Space Research/, /Volume 6, Issue 1/, /1986/, /Pages 315-327/ Malcolm B. Niedner Jr *Abstract* As a result of the visibility imparted by fluorescing ions (mostly CO^+ and H_2 O^+ ), cometary plasma tails are the image variety of magnetotails whose large-scale structure and image temporal variations can be studied from a single observation, or pair of observations, respectively; the type of data is wide-field (≥ 5°) imagery. When concurrent solar-wind and interplanetary magnetic field (IMF) data are available (near-Earth, interplanetary, or-- preferably--near-comet), the opportunity exists for studying the large-scale comet/solar-wind interaction. The purposes of the present paper are to review, briefly, some of the principal results which existed before the present apparition of Halley's Comet, but mostly to present initial findings based on the Halley imaging data returned by the Large-Scale Phenomena Network of the International Halley Watch. Most of the latter discussion will concentrate on Disconnection Events (DE's) and the overall interaction of bright comets with the IMF. The importance of correlative studies utilizing remote imaging and the near-comet solar wind/IMF data returned by the Halley Armada spacecraft is particularly stressed. An exciting initial result is that the cometary magnetic barriers observed by VEGA-1 and VEGA-2 had opposite magnetic polarities, in agreement with the frontside magnetic reconnection model of DE's /1/ and with the fact that a major DE took place on 8 March 1986, between the VEGA-1 and VEGA-2 encounters. Purchase PDF (1303 K) The cometary magnetic field and its associated electric... /Icarus/ Close You are not entitled to access the full text of this document *The cometary magnetic field and its associated electric currents Original Research Article* /Icarus/, /Volume 26, Issue 4/, /December 1975/, /Pages 457-461/ W-H. Ip, D. A. Mendis *Abstract* Two different observations of Comet Kohoutek (1973f) seem to suggest the existence of substantial magnetic fields (greater-than or equivalent to 100 γ) in its coma and tail. The effects of the currents and hydromagnetic waves associated with these magnetic fields are considered and it is shown that while the currents closing through the inner coma may represent an important source of ionization in that region, the dissipation of hydromagnetic waves may also be a significant, if not dominant, source of heating there. Purchase PDF (456 K) Three-dimensional model of ray structure formation in c... /Planetary and Space Science/ Close You are not entitled to access the full text of this document *Three-dimensional model of ray structure formation in cometary plasma tails Original Research Article* /Planetary and Space Science/, /Volume 42, Issue 9/, /September 1994/, /Pages 733-736/ Nikolay Ya. Kotsarenko, Olga P. Verkhoglyadova, Klim I. Churyumov *Abstract* The theoretical model of large-scale ray structure formation proposed in a preceding paper (Verkhoglyadova et al., Lett. Russ. Astro. J., 19, 823–869, 1993) resides in filamentation instability development due to the solar wind flow partially penetrating into the cometary plasma tail. In order to study a real form of the filaments and instability development in space a study of the proposed mechanism in three dimensions is made. Cometary plasma ions and those of the solar wind seem to be collisionless, otherwise collisions of electrons dealing with scattering on ion-acoustic oscillations are characterized by effective collision frequency. The cometary plasma filaments, which are observed as bright rays, are formed due to instability development and take the form of cylindrical plasma fibers with the thickness determined by cometary plasma parameters and those of the solar wind. Under some assumptions we obtain the characteristic length which may be thought of as the maximum ray size. We evaluate the number of rays within one lobe of cometary plasma tail which varies at a range of 2–30 rays. The observational evolution of the ray structure is discussed. 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Russell Click here for a PDF excerpt Purchase PDF (1222 K) Geomagnetism /Encyclopedia of Physical Science and Technology/ Close You are not entitled to access the full text of this document *Geomagnetism * /Encyclopedia of Physical Science and Technology/, /2004/, /Pages 663-674/ Ronald T. Merrill, Phillip L. McFadden Click here for a PDF excerpt Purchase PDF (546 K) Magnetism, History of /Encyclopedia of Condensed Matter Physics/ Close You are not entitled to access the full text of this document *Magnetism, History of * /Encyclopedia of Condensed Matter Physics/, /2005/, /Pages 227-236/ J. M. D. Coey, T. R. Ní Mhíocháin Click here for a PDF excerpt Purchase PDF (948 K) More related reference work articles PANGAEA Supplementary Data View Record in Scopus * Purchase PDF (418 K) * Export citation Abstract Abstract - selected References References - selected Return your view to full page Focus your view on this article *Icarus* Volume 29, Issue 1 , September 1976, Pages 147-151 ------------------------------------------------------------------------ doi:10.1016/0019-1035(76)90110-X | How to Cite or Link Using DOI Copyright © 1976 Published by Elsevier Science (USA). Cited By in Scopus (4) Permissions & Reprints The generation of magnetic fields and electric currents in cometary plasma tails Purchase the full-text article References and further reading may be available for this article. To view references and further reading you must purchase this article. *W-H. Ip and D. A. Mendis* Department of Applied Physics and Information Science, University of California, San Diego, La Jolla, California 92093, USA Received 1 October 1975; revised 5 December 1975. Available online 26 October 2002. Abstract Due to the folding of the interplanetary magnetic field into the tail as a comet sweeps through the interplanetary medium, the magnetic field in the tail can be built up to the order of 100 γ at a heliocentric distance ≈1 AU. This folding of magnetic flux tubes also results in a cross-tail electric current passing through a neutral sheet. When streams of enhanced plasma density merge with the main tail, cross-tail currents as large as 10^9 A may result. A condition could arise which causes a significant fraction of this current to be discharged through the inner coma, resulting in rapid ionization. The typical time scale for such outbursts of ionization is estimated to be of the order of 10^4 sec, which is in reasonable agreement with observation. Article Outline • References ------------------------------------------------------------------------ *Icarus* Volume 29, Issue 1 , September 1976, Pages 147-151 Sponsored Links Full-Text Online Journals Full-text journals for academic research at Questia Online Library. www.Questia.com/Journals What is Quantum Jumping? Discover Why Thousands of People are "Jumping" to Change Their Life www.QuantumJumping.com The Art Institute Online Attend Photography School Online. Classes Begin Soon - Learn More! www.aionline.edu * Home * Browse * Search * My settings * My alerts * Help Elsevier homepage (opens in a new window) * *About ScienceDirect* * o What is ScienceDirect o Content details o Set up o How to use o Subscriptions o Developers * *Contact and Support* * o Contact and Support * *About Elsevier* * o About Elsevier o About SciVerse o About SciVal o Terms and Conditions o Privacy policy o Information for advertisers Copyright © 2011 Elsevier B.V. All rights reserved. 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