Sign on

SAO/NASA ADS Astronomy Abstract Service

· Find Similar Abstracts (with default settings below)
· Electronic Refereed Journal Article (HTML)
· Full Refereed Journal Article (PDF/Postscript)
· References in the article
· Citations to the Article (18) (Citation History)
· Refereed Citations to the Article
· Also-Read Articles (Reads History)
·
· Translate This Page
Title:
Mapping the Distribution of Electron Temperature and Fe Charge States in the Corona with Total Solar Eclipse Observations
Authors:
Habbal, S. Rifai; Druckmüller, M.; Morgan, H.; Daw, A.; Johnson, J.; Ding, A.; Arndt, M.; Esser, R.; Rušin, V.; Scholl, I.
Affiliation:
AA(Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA ), AB(Faculty of Mechanical Engineering, Brno University of Technology, 616 69 Brno, Czech Republic), AC(Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA), AD(Appalachian State University, Boone, NC 28608, USA; NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA), AE(Electricon, Boulder, CO 80204, USA), AF(Institute of Optics and Atomic Physics, Technische Universität Berlin and Institute of Technical Physics, Berlin, Germany), AG(Bridgewater State College, Bridgewater, MA 02325, USA), AH(University of Tromsø, Norway), AI(Astronomical Institute, Slovak Academy of Sciences, 059 60 Tatranska Lomnica, Slovak Republic), AJ(Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA)
Publication:
The Astrophysical Journal, Volume 708, Issue 2, pp. 1650-1662 (2010). (ApJ Homepage)
Publication Date:
01/2010
Origin:
IOP
Astronomy Keywords:
eclipses, solar wind, Sun: corona
DOI:
10.1088/0004-637X/708/2/1650
Bibliographic Code:
2010ApJ...708.1650H

Abstract

The inference of electron temperature from the ratio of the intensities of emission lines in the solar corona is valid only when the plasma is collisional. Once collisionless, thermodynamic ionization equilibrium no longer holds, and the inference of an electron temperature and its gradient from such measurements is no longer valid. At the heliocentric distance where the transition from a collision-dominated to a collisionless plasma occurs, the charge states of different elements are established, or frozen-in. These are the charge states which are subsequently measured in interplanetary space. We show in this study how the 2006 March 29 and 2008 August 1 eclipse observations of a number of Fe emission lines yield an empirical value for a distance, which we call Rt , where the emission changes from being collisionally to radiatively dominated. Rt ranges from 1.1 to 2.0 R sun, depending on the charge state and the underlying coronal density structures. Beyond that distance, the intensity of the emission reflects the distribution of the corresponding Fe ion charge states. These observations thus yield the two-dimensional distribution of electron temperature and charge state measurements in the corona for the first time. The presence of the Fe X 637.4 nm and Fe XI 789.2 nm emission in open magnetic field regions below Rt , such as in coronal holes and the boundaries of streamers, and the absence of Fe XIII 1074.7 nm and Fe XIV 530.3 nm emission there indicate that the sources of the solar wind lie in regions where the electron temperature is less than 1.2 × 106 K. Beyond Rt , the extent of the Fe X [Fe9+] and Fe XI emission [Fe10+], in comparison with Fe XIII [Fe12+] and Fe XIV [Fe13+], matches the dominance of the Fe10+ charge states measured by the Solar Wind Ion Composition Spectrometer, SWICS, on Ulysses, at -43° latitude at 4 AU, in March-April 2006, and Fe9+ and Fe10+ charge states measured by SWICS on the Advanced Composition Explorer, ACE, in the ecliptic plane at 1 AU, at the time of both eclipses. The remarkable correspondence between these two measurements establishes the first direct link between the distribution of charge states in the corona and in interplanetary space.
Bibtex entry for this abstract   Preferred format for this abstract (see Preferences)
   

Find Similar Abstracts:

Use: Authors
Title
Keywords (in text query field)
Abstract Text
Return: Query Results Return    items starting with number
Query Form
Database: Astronomy
Physics
arXiv e-prints