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Title: ACE/SWICS OBSERVATIONS OF HEAVY ION DROPOUTS WITHIN THE SOLAR WIND

Abstract

We present the first in situ observations of heavy ion dropouts within the slow solar wind, observed for select elements ranging from helium to iron. For iron, these dropouts manifest themselves as depletions of the Fe/H ratio by factors up to {approx}25. The events often exhibit mass-dependent fractionation and are contained in slow, unsteady wind found within a few days from known stream interfaces. We propose that such dropouts are evidence of gravitational settling within large coronal loops, which later undergo interchange reconnection and become source regions of slow, unsteady wind. Previously, spectroscopic studies by Raymond et al. in 1997 (and later Feldman et al. in 1999) have yielded strong evidence for gravitational settling within these loops. However, their expected in situ signature plasma with heavy elements fractionated by mass was not observed prior to this study. Using data from the SWICS instrument on board the Advanced Composition Explorer (ACE), we investigate the composition of the solar wind within these dropouts and explore long term trends over most of a solar cycle.

Authors:
 [1];  [2]
  1. PhD Candidate in Space and Planetary Physics, 2435 Space Research Building, 2455 Hayward Street, Ann Arbor, MI 48109-2143, USA. (United States)
  2. Professor, Space Science and Aerospace Engineering, Associate Dean for Entrepreneurship, 2429 Space Research Building, 2455 Hayward Street, Ann Arbor, MI 48109-2143, USA. (United States)
Publication Date:
OSTI Identifier:
22086330
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 760; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; ELEMENT ABUNDANCE; FRACTIONATION; HEAVY IONS; HELIOSPHERE; HELIUM; INTERFACES; IRON; MASS; PLASMA; SOLAR CYCLE; SOLAR WIND; SUN

Citation Formats

Weberg, Micah J, Zurbuchen, Thomas H, and Lepri, Susan T., E-mail: mjweberg@umich.edu, E-mail: thomasz@umich.edu, E-mail: slepri@umich.edu. ACE/SWICS OBSERVATIONS OF HEAVY ION DROPOUTS WITHIN THE SOLAR WIND. United States: N. p., 2012. Web. doi:10.1088/0004-637X/760/1/30.
Weberg, Micah J, Zurbuchen, Thomas H, & Lepri, Susan T., E-mail: mjweberg@umich.edu, E-mail: thomasz@umich.edu, E-mail: slepri@umich.edu. ACE/SWICS OBSERVATIONS OF HEAVY ION DROPOUTS WITHIN THE SOLAR WIND. United States. https://doi.org/10.1088/0004-637X/760/1/30
Weberg, Micah J, Zurbuchen, Thomas H, and Lepri, Susan T., E-mail: mjweberg@umich.edu, E-mail: thomasz@umich.edu, E-mail: slepri@umich.edu. 2012. "ACE/SWICS OBSERVATIONS OF HEAVY ION DROPOUTS WITHIN THE SOLAR WIND". United States. https://doi.org/10.1088/0004-637X/760/1/30.
@article{osti_22086330,
title = {ACE/SWICS OBSERVATIONS OF HEAVY ION DROPOUTS WITHIN THE SOLAR WIND},
author = {Weberg, Micah J and Zurbuchen, Thomas H and Lepri, Susan T., E-mail: mjweberg@umich.edu, E-mail: thomasz@umich.edu, E-mail: slepri@umich.edu},
abstractNote = {We present the first in situ observations of heavy ion dropouts within the slow solar wind, observed for select elements ranging from helium to iron. For iron, these dropouts manifest themselves as depletions of the Fe/H ratio by factors up to {approx}25. The events often exhibit mass-dependent fractionation and are contained in slow, unsteady wind found within a few days from known stream interfaces. We propose that such dropouts are evidence of gravitational settling within large coronal loops, which later undergo interchange reconnection and become source regions of slow, unsteady wind. Previously, spectroscopic studies by Raymond et al. in 1997 (and later Feldman et al. in 1999) have yielded strong evidence for gravitational settling within these loops. However, their expected in situ signature plasma with heavy elements fractionated by mass was not observed prior to this study. Using data from the SWICS instrument on board the Advanced Composition Explorer (ACE), we investigate the composition of the solar wind within these dropouts and explore long term trends over most of a solar cycle.},
doi = {10.1088/0004-637X/760/1/30},
url = {https://www.osti.gov/biblio/22086330}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 760,
place = {United States},
year = {Tue Nov 20 00:00:00 EST 2012},
month = {Tue Nov 20 00:00:00 EST 2012}
}