E-Print Archive

There are 4553 abstracts currently viewable.


Advanced Search
Main Page Add New E-Print Submitter
News Help/FAQ About Preferences
Manage Key Phrase
Observations from Hinode/EIS of intensity oscillations above a bright point: signature of the leakage of acoustic oscillations in the inner corona View all abstracts by submitter

Dr. A.K. Srivastava   Submitted: 2010-06-04 04:43

We study the intensity oscillations in the upper chromosphere/transition region (TR) and corona, above a bright point (BP) in the solar atmosphere. We analyse the time series of HeII 256 ?, FeXII 195 Å and FeXV 284 ?, observed in a 40-arcsec slot close to the centre of the Sun above the BP by the extreme ultraviolet (EUV) imaging spectrometer (EIS) on board Hinode. Using standard wavelet and periodogram tools, we produce power spectra of intensity oscillations. In the HeII 256.32 ? and FeXII 195.12 Å EUV light curves, we detect intensity oscillations of the periods ~ 263 ± 80 s and ~ 241 ± 60 s, respectively, with a probability >95 per cent in wavelets, which are also consistent with their periodograms. This provides the most likely signature of the propagation of acoustic oscillations around the ~5.0-min period from the photosphere to the inner corona. The radiative cooling and thus the finite radiative relaxation time are found to be the most likely mechanisms for the reduced cut-off frequency environment above the observed BP. This may allow the transfer of ~5.0-min acoustic oscillations from the upper chromosphere/TR into the corona. We find that intensity oscillations in HeII 256.32 ? show temporal damping during the total span of the observation. This may be the first most likely observational signature of acoustic wave damping in the upper chromosphere caused by the radiative cooling effect. The intensity oscillations in FeXII 195.12 Å show an amplification, which may be a most likely signature of the mode-coupling (two-wave interaction) and then resonant energy conversion, probably from transverse magnetohydrodynamic (MHD) waves of the double period (e.g. Alfvén waves) to the observed acoustic waves in the lower solar atmosphere where the plasma beta tends to unity. However, we find no evidence of real oscillations around the ~5.0-min period with its amplification in the higher corona where the FeXV 284.16 ? line is formed, which rules out this type of wave activity there. Almost 1.6 per cent of the solar surface is covered with small BPs, probably associated with the small-scale closed-loop system, which may be a subset of expanding flux tubes. Hence, the leakage of ~5.0-min oscillations above such BPs, which is associated with the highest powers of strong convective motions, and probably resonantly amplified by transverse MHD waves (e.g. Alfvén waves), may be significant for heating the solar atmosphere locally.

Authors: Srivastava, A. K.; Dwivedi, B. N.
Projects: None

Publication Status: MNRAS
Last Modified: 2010-06-04 07:44
Go to main E-Print page  Slow shocks and conduction fronts from Petschek reconnection of skewed magnetic fields: two-fluid effects   How to deal with measurement errors and lacking data in nonlinear force-free coronal magnetic field modelling?  Edit Entry  Download Preprint  Delete Entry 

Go to main E-Print pageGo to main E-Print page.
Previous AbstractPrevious Abstract.
Next AbstractNext Abstract.
Download PreprintDownload Preprint.
Submitter's HomepageSubmitters Homepage.
Edit EntryEdit Entry.
View All Abstracts By SubmitterView all abstracts by submitter.
Delete AbstractDelete abstract.

Latest Entries
Stability of slow magnetoacoustic and entropy waves in the solar coronal plasma with thermal misbalance
The chromosphere underneath a Coronal Bright Point
Characterising fast-time variations in the hard X-ray time profiles of solar flares using Solar Orbiter's STIX
The quiet sun at mm wavelengths as seen by ALMA
Explosive Events in the Quiet Sun Near and Beyond the Solar Limb Observed with the Interface Region Imaging Spectrograph (IRIS)
Multi-stage reconnection powering a solar coronal jet
A Statistical Analysis of Magnetic Field Changes in the Photosphere during Solar Flares Using High-cadence Vector Magnetograms and Their Association with Flare Ribbons
Numerical Study on Excitation of Turbulence and Oscillation in Above-the-loop-top Region of a Solar Flare
Oscillatory reconnection as a plasma diagnostic in the solar corona
The independence of oscillatory reconnection periodicity from the initial pulse
Oscillatory Reconnection of a 2D X-point in a hot coronal plasma
Formation Of The Lyman Continuum During Solar Flares
MHD simulation of Solar Eruption from Active Region 11429 Driven by Photospheric Velocity Field
Unfolding Drift Effects for Cosmic Rays over the Period of the Sun's Magnetic Field Reversal
Problems in Observation and Identification of Torsional Waves in the Lower Solar Atmosphere
Solar Orbiter and SDO Observations, and Bifrost MHD Simulations of Small-scale Coronal Jets
Dominance of Bursty over Steady Heating of the 48 MK Coronal Plasma in a Solar Active Region: Quantification Using Maps of Minimum, Maximum, and Average Brightness
Solar flare hard X-rays from the anchor points of an eruptive filament
Plasmoids, Flows, and Jets During Magnetic Reconnection in a Failed Solar Eruption
Connecting Chromospheric Condensation Signatures to Reconnection-driven Heating Rates in an Observed Flare

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

© 2000-2020 Solar Physics Group - Montana State University