E-Print Archive

There are 3897 abstracts currently viewable.


Search:

Advanced Search
Options
Main Page Add New E-Print Submitter
Information
Feedback
News Help/FAQ About Preferences
Manage Key Phrase
Notification
Transient induced MHD oscillations : A tool to probe the solar active regions  

Dr. A.K. Srivastava   Submitted: 2011-10-07 01:37

Solar transients and eruptive phenomena which are ubiquitous in the solaratmosphere, can shed new light to the understanding of the outstanding problemslike coronal heating and the solar wind acceleration. Observations in theentire electromagnetic spectrum of such dynamical processes of large andsmall-scale transient/eruptive events, with highly dynamic magnetic fieldconfiguration, and energetic particles, provide crucial information about theplasma processes at mega-Kelvin temperature embedded in a complex magneticfield, and also energy build-up/energy-release processes, taking place in suchevents. One of the most important phenomenological aspects of solar eruptivephenomena is the induced magnetohydrodynamic (MHD) waves generated during theseenergetic processes, which carry a potential signature to probing the solaractive regions. In this paper, we briefly review the recent trends of thetransient (e.g., flares) induced quasi-periodic oscillations in the solaratmosphere and discuss their implications in diagnosing the solar activeregions, providing the clue to understanding local plasma dynamics and heating.

Authors: Srivastava, Abhishek K.; Nakariakov, V. M.; Dwivedi, B. N.; Kumar, Pankaj
Projects: None

Publication Status: 6 pages, 2 figures, to be appear in the Proc. of the 1st Asian-Pacific Solar Phys. Meeting
Last Modified: 2011-10-08 12:25
Go to main E-Print page  Edit Entry  Download Preprint  Delete Entry 

Evidence of wave harmonics in a brightened magnetic network observed from Hinode/EIS  

Dr. A.K. Srivastava   Submitted: 2010-04-22 01:52

We study intensity oscillations in the upper chromosphere to search acoustic wave harmonics in a low-atmospheric solar cavity associated with a brightened magnetic network near the south pole of the Sun. We use a wavelet tool to produce power spectrum of He II 256.32 ? intensity oscillation as observed by EUV Imaging Spectrometer (EIS) onboard Hinode spacecraft. We detect a periodicity of 14.33 min with a probability of 99%?100%. Using wavelet filtering and reconstruction techniques, we detect other statistically significant periodicities of 8.51 min and 5.51 min with the probabilities 98% and 97% respectively. These observed periodicities provide the first possible signature of acoustic wave harmonics in a low-atmospheric cavity-canopy system. The ratio of the period of first harmonic (P1 = 14.33 min) to the period of second harmonic (P2 = 8.51 min) is 1.68. The difference of this period ratio from 2.0 may be the first signature of a density stratification in low-atmospheric solar cavities, complementing such period ratio differences of acoustic wave harmonics have been reported previously in the solar loops as a diagnostic of their density stratification. We seismologically estimate the density scale height as 0.57 Mm in the cavity?canopy loop interface. This scale height is low compared to the hydrostatic scale heights estimated at wide range of temperatures that correspond to the considerable formation of He II ion in the lower solar atmosphere. The departure of density scale height estimated by the principle of MHD seismology from the values of hydrostatic scale heights estimated at wide temperature range (4.2 < Log Te < 5.2), probably indicates non-hydrostatic conditions above the cavity?canopy interface.

Authors: A.K. Srivastava
Projects: None

Publication Status: New Astronomy, 2010, Vol : 15, pp : 621-627
Last Modified: 2010-04-22 06:46
Go to main E-Print page  Edit Entry  Download Preprint  Delete Entry 


Key
Go to main E-Print pageGo to main E-Print page.
Download PreprintDownload Preprint.
Submitter's HomepageSubmitters Homepage.
Edit EntryEdit Entry.
Delete AbstractDelete abstract.

Abstracts by Author
Transient induced MHD oscillations : A tool to probe the solar active regions
Evidence of wave harmonics in a brightened magnetic network observed from Hinode/EIS

Related Pages
MSU Solar Physics.
Max Millennium Science Mail Archive.
Max Millennium Message of the Day Mail Archive.
Max Millennium Flare Catalog

Archive Maintainer
Alisdair Davey



© 2003 Solar Physics Group - Montana State University