E-Print Archive

There are 3923 abstracts currently viewable.


Advanced Search
Main Page Add New E-Print Submitter
News Help/FAQ About Preferences
Manage Key Phrase
IRIS Observations of Spicules and Structures Near the Solar Limb View all abstracts by submitter

Costas Alissandrakis   Submitted: 2018-01-12 00:07

We have analyzed IRIS spectral and slit-jaw observations of a quiet region near the South Pole. In this article we present an overview of the observations, the corrections, and the absolute calibration of the intensity. We focus on the average profiles of strong (Mg ii h and k, C ii and Si iv), as well as of weak spectral lines in the near ultraviolet (NUV) and the far ultraviolet (FUV), including the Mg ii triplet, thus probing the solar atmosphere from the low chromosphere to the transition region. We give the radial variation of bulk spectral parameters as well as line ratios and turbulent velocities. We present measurements of the formation height in lines and in the NUV continuum, from which we find a linear relationship between the position of the limb and the intensity scale height. We also find that low forming lines, such as the Mg ii triplet, show no temporal variations above the limb associated with spicules, suggesting that such lines are formed in a homogeneous atmospheric layer and, possibly, that spicules are formed above the height of 2 arc sec. We discuss the spatio-temporal structure near the limb from images of intensity as a function of position and time. In these images, we identify p-mode oscillations in the cores of lines formed at low heights above the photosphere, slow moving bright features in O i and fast moving bright features in C ii. Finally, we compare the Mg ii k and h line profiles, together with intensity values of the Balmer lines from the literature, with computations from the PROM57Mg non-LTE model developed at the Institut d'Astrophysique Spatiale and estimated values of the physical parameters. We obtain electron temperatures in the range of 8000 K at small heights to 20000 K at large heights, electron densities from 1.1x1011 to 4x1010 cm-3 and a turbulent velocity of about 24 km s-1.

Authors: C. E. Alissandrakis,  J.-C. Vial, A. Koukras,  E. Buchlin,  M. Chane-Yook
Projects: IRIS

Publication Status: In press, Solar Physics
Last Modified: 2018-01-14 00:01
Go to main E-Print page  Spectroscopic Observations of a Current Sheet in a Solar Flare  Strong Transverse Photosphere Magnetic Fields and Twist in Light Bridge Dividing Delta Sunspot of Active Region 12673  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
Non-stationary quasi-periodic pulsations in solar and stellar flares
Lost and found sunquake in the 6 September 2011 flare caused by beam electrons
Nonkinematic solar dynamo models with double-cell meridional circulation
Solar Kinetic Energy and Cross Helicity Spectra
Collective Study of Polar Crown Filaments in the Past Four Solar Cycles
Highly Ionized Calcium and Argon X-ray Spectra from a Large Solar Flare
Detecting the solar new magnetic flux regions on the base of vector magnetograms
A Truly Global EUV Wave From the SOL2017-09-10 X8.2 Solar Flare-CME Eruption
Photospheric Shear Flows in Solar Active Regions and Their Relation to Flare Occurrence
Linear Polarization Features in the Quiet-Sun Photosphere: Structure and Dynamics
Solar Microflares Observed by SphinX and RHESSI
Two Kinds of Dynamic Behavior in a Quiescent Prominence Observed by the NVST
Resistively-limited current sheet implosions in planar anti-parallel (1D) and null-point containing (2D) magnetic field geometries
Is It Small-scale Weak Magnetic Activity That Effectively Heats the Upper Solar Atmosphere?
Self-Similar Approach for Rotating Magnetohydrodynamic Solar and Astrophysical Structures
Spectroscopic and imaging observations of small-scale reconnection events
A Study of Magnetic Field Characteristics of Flaring Active Region Based on Nonlinear Force-free Field Extrapolation
A Study of a Compound Solar Eruption with Two Consecutive Erupting Magnetic Structures
Non-potential magnetic helicity ratios at the onset of eruptions

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