Projects per year
Abstract
Observations of slow magneto-acoustic waves have been demonstrated to
possess a number of applications in coronal seismology. Determination of
the polytropic index ($\gamma$) is one such important application.
Analysing the amplitudes of oscillations in temperature and density
corresponding to a slow magneto-acoustic wave, the polytropic index in
the solar corona has been calculated and based on the obtained value it
has been inferred that thermal conduction is highly suppressed in a very
hot loop in contrast to an earlier report of high thermal conduction in
a relatively colder loop. In this study, using SDO/AIA data, we analysed
slow magneto-acoustic waves propagating along sunspot fan loops from 30
different active regions and computed polytropic indices for several
loops at multiple spatial positions. The obtained $\gamma$ values vary
from 1.04$\pm$0.01 to 1.58$\pm$0.12 and most importantly display a
temperature dependence indicating higher $\gamma$ at hotter
temperatures. This behaviour brings both the previous studies to
agreement and perhaps implies a gradual suppression of thermal
conduction with increase in temperature of the loop. The observed phase
shifts between temperature and density oscillations, however, are
substantially larger than that expected from a classical thermal
conduction and appear to be influenced by a line-of-sight integration
effect on the emission measure.
Original language | English |
---|---|
Article number | 149 |
Pages (from-to) | 1-9 |
Journal | The Astrophysical Journal |
Volume | 868 |
DOIs | |
Publication status | Published - 04 Dec 2018 |
Keywords
- Astrophysics - Solar and Stellar Astrophysics
Fingerprint
Dive into the research topics of 'The polytropic index of solar coronal plasma in sunspot fan loops and its temperature dependence'. Together they form a unique fingerprint.Projects
- 1 Finished
-
R1309APL: Waves and Flows: Linking the Solar Photosphere to the Corona
Jess, D. (PI)
01/08/2012 → 23/06/2018
Project: Research