Record Details

Record 1 of 1
Persistent Doppler Shift Oscillations Observed with HINODE-EIS in the Solar Corona: Spectroscopic Signatures of Alfvenic Waves and Recurring Upflows
NTRS Full-Text: Click to View  [PDF Size: 1.3 MB]
External Online Source: doi:10.1088/0004-637X/759/2/144
Author and Affiliation:
Tian, Hui(National Center for Atmospheric Research, Boulder, CO, United States);
McIntosh, Scott W.(National Center for Atmospheric Research, Boulder, CO, United States);
Wang, Tongjiang(Catholic Univ. of America, Department of Physics, Washington, DC, United States);
Offman, Leon(Catholic Univ. of America, Department of Physics, Washington, DC, United States);
De Pontieu, Bart(Lockheed Martin Corp., Solar and Astrophysics Laboratory, Palo Alto, CA, United States);
Innes, Davina E.(Max-Planck Inst. for Solar System Research, Germany);
Peter, Hardi(Max-Planck Inst. for Solar System Research, Germany)
Abstract: Using data obtained by the EUV Imaging Spectrometer on board Hinode, we have performed a survey of obvious and persistent (without significant damping) Doppler shift oscillations in the corona. We have found mainly two types of oscillations from February to April in 2007. One type is found at loop footpoint regions, with a dominant period around 10 minutes. They are characterized by coherent behavior of all line parameters (line intensity, Doppler shift, line width, and profile asymmetry), and apparent blueshift and blueward asymmetry throughout almost the entire duration. Such oscillations are likely to be signatures of quasi-periodic upflows (small-scale jets, or coronal counterpart of type-II spicules), which may play an important role in the supply of mass and energy to the hot corona. The other type of oscillation is usually associated with the upper part of loops. They are most clearly seen in the Doppler shift of coronal lines with formation temperatures between one and two million degrees. The global wavelets of these oscillations usually peak sharply around a period in the range of three to six minutes. No obvious profile asymmetry is found and the variation of the line width is typically very small. The intensity variation is often less than 2%. These oscillations are more likely to be signatures of kink/Alfv´en waves rather than flows. In a few cases, there seems to be a p/2 phase shift between the intensity and Doppler shift oscillations, which may suggest the presence of slow-mode standing waves according to wave theories. However, we demonstrate that such a phase shift could also be produced by loops moving into and out of a spatial pixel as a result of Alfv´enic oscillations. In this scenario, the intensity oscillations associated with Alfv´enic waves are caused by loop displacement rather than density change. These coronal waves may be used to investigate properties of the coronal plasma and magnetic field.
Publication Date: Oct 29, 2012
Document ID:
20140010227
(Acquired Aug 22, 2014)
Subject Category: ASTROPHYSICS
Report/Patent Number: GSFC-E-DAA-TN10040
Document Type: Journal Article
Publication Information: The Astrophysical Journal; Volume 759; Issue 2; 144; (SEE 20130005265)
Publisher Information: The American Astronomical Society
Contract/Grant/Task Num: NNX08AL22G; NNX08BA99G; NSF ATM-0541567; NSF ATM-0925177; NNX10AN10G; NNX12AB34G; NNG11PL10A
Financial Sponsor: NASA Goddard Space Flight Center; Greenbelt, MD United States
Organization Source: NASA Goddard Space Flight Center; Greenbelt, MD United States
Description: 17p; In English; Original contains color illustrations
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright; Distribution under U.S. Government purpose rights
NASA Terms: PHASE SHIFT; MAGNETOHYDRODYNAMIC WAVES; DOPPLER EFFECT; OSCILLATIONS; SOLAR CORONA; SPECTROSCOPY; SOLAR WIND VELOCITY; DATA REDUCTION; DENSITY (MASS/VOLUME); TIME LAG; SPECTRAL LINE WIDTH; MODES (STANDING WAVES)
Other Descriptors: SOLAR CORONA; WAVES; EUV OBSERVATION
› Back to Top
Facebook icon, External Link to NASA STI page on Facebook Twitter icon, External Link to NASA STI on Twitter YouTube icon, External Link to NASA STI Channel on YouTube RSS icon, External Link to New NASA STI RSS Feed
Find Similar Records
 
NASA Logo, External Link

NASA Official: Gerald Steeman

Sponsored By: NASA Scientific and Technical Information Program

Site Curator: STI Support Services

Last Modified: October 24, 2014

Privacy Policy & Important Notices Disclaimers, Copyright, Terms of Use Freedom of Information Act USA.gov NASA.gov NASA OCIO Free Adobe PDF Reader Free MS Word Viewer