The Library
Statistical seismology of transverse waves in the solar corona
Tools
Verwichte, E. (Erwin), Doorsselaere, Tom, White, R. S. and Antolin, P. (2013) Statistical seismology of transverse waves in the solar corona. Astronomy & Astrophysics, Volume 552 . Article number A138. doi:10.1051/0004-6361/201220456 ISSN 0004-6361.
Research output not available from this repository.
Request-a-Copy directly from author or use local Library Get it For Me service.
Official URL: http://dx.doi.org/10.1051/0004-6361/201220456
Abstract
Context. Observations show that transverse oscillations occur commonly in solar coronal loops. The rapid damping of these waves has been attributed to resonant absorption. The oscillation characteristics carries information of the structuring of the corona. However,
self-consistent seismological methods to extract information from individual oscillations is limited because there are less observables than model unknown parameters and the problem is underdetermined. Furthermore, it has been shown that one-to-one comparisons of the observed scaling of period and damping times with wave damping theories is misleading.
Aims. We aim to investigate if seismological information can be gained from the observed scaling laws in a statistical sense.
Methods. A statistical approach is used whereby scaling-laws are produced by forward modelling using distributions of values for
key loop cross-sectional structuring parameters. We study two types of observations: 1) transverse loops oscillations as seen mainly
with TRACE and SDO and 2) running transverse waves seen with CoMP.
Results. We demonstrate that the observed period-damping time scaling law does provide information about the physical damping
mechanism, if observations are collected from as wide as possible range of periods and a comparison with theory is performed in a statistical sense. The distribution of the ratio of damping time over period, i.e. the quality factor, has been derived analytically and fitted to the observations. A minimum value for the quality factor of 0.65 has been found. From this, a constraint linking the ranges of possible values for the density contrast and inhomogeneity layer thickness is obtained for transverse loop oscillations. If the layer thickness is not constrained, then the density contrast is maximally equal to 3. For transverse waves seen by CoMP, it is found that the
ratio of maximum to minimum values for these two parameters has to be less than 2.06. i.e. the sampled values for the layer thickness and Alfven travel time comes from a relatively narrow distribution. ´
Conclusions. Now that more and more transverse loop oscillations have been analysed, a statistical approach to coronal seismology
becomes possible. Using the observed data cloud restrictions in the loop parameter space of density contrast and inhomogeneity layer
thickness are found and surprisingly for the running waves narrow distributions for loop parameters have been found.
Item Type: | Journal Article | ||||
---|---|---|---|---|---|
Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | ||||
Journal or Publication Title: | Astronomy & Astrophysics | ||||
Publisher: | EDP Sciences | ||||
ISSN: | 0004-6361 | ||||
Official Date: | April 2013 | ||||
Dates: |
|
||||
Volume: | Volume 552 | ||||
Number of Pages: | 9 | ||||
Page Range: | Article number A138 | ||||
DOI: | 10.1051/0004-6361/201220456 | ||||
Status: | Peer Reviewed | ||||
Publication Status: | Published | ||||
Access rights to Published version: | Restricted or Subscription Access |
Request changes or add full text files to a record
Repository staff actions (login required)
View Item |