E-Print Archive

There are 4050 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
Lyman Continuum Observations of Solar Flares Using SDO/EVE View all abstracts by submitter

Ryan Milligan   Submitted: 2018-10-25 23:42

The Extreme ultraviolet Variability Experiment was designed to observe the Sun-as-a-star in the extreme ultraviolet; a wavelength range that has remained spectrally unresolved for many years. It has provided a wealth of data on solar flares, perhaps most uniquely, on the Lyman spectrum of hydrogen at high cadence and moderate spectral resolution. In this paper we concentrate on the analysis of Lyman continuum (LyC) observations and its temporal evolution in a sample of six major solar flares. By fitting both the pre-flare and flare excess spectra with a blackbody function we show that the color temperature derived from the slope of LyC reveals temperatures in excess of 104 K in the six events studied; an increase of a few thousand Kelvin above quiet-Sun values (typically ~8000-9500 K). This was found to be as high as 17000 K for the 2017 September 6 X9.3 flare. Using these temperature values, and assuming a flaring area of 1018 cm2, estimates of the departure coefficient of hydrogen, b1, were calculated. It was found that b1 decreased from 102-103 in the quiet-Sun, to around unity during the flares. This implies that LyC is optically thick and formed in local thermodynamic equilibrium during flares. It also emanates from a relatively thin (≲100 km) shell formed at deeper, denser layers than in the quiescent solar atmosphere. We show that in terms of temporal coverage and resolution, EVE gives a more comprehensive picture of the response of the chromosphere to the flare energy input with respect to those of the Skylab/Harvard College Observatory spatially resolved observations of the 1970's.

Authors: Marcos E. Machado, Ryan O. Milligan, Paulo J. A. Simões
Projects: None

Publication Status: Accepted for publication in ApJ.
Last Modified: 2018-10-26 11:49
Go to main E-Print page  On the Extrapolation of Magnetohydrostatic Equilibria on the Sun  Buoyancy-driven Magnetohydrodynamic Waves in a Partially Ionized Plasma  Edit Entry  Download Preprint  Delete Entry 

Key
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
The Physical Nature of Spiral Wave Patterns in Sunspots
Predicting Solar Flares Using a Long Short-Term Memory Network
Coronal loop transverse oscillations excited by different driver frequencies
Solar Center-Limb Variation of the Strengths of Spectral Lines: Classification and Interpretation of Observed Trends
The plasmoid instability in a confined solar flare
High-frequency dynamics of active region moss as observed by IRIS
Extreme-ultraviolet Late Phase Caused by Magnetic Reconnection over Quadrupolar Magnetic Configuration in a Solar Flare
Two-step evolution of a rising flux rope resulting in a confined solar flare
Why torus-unstable solar filaments experience failed eruption?
The Magnetic Properties of Heating Events on High-Temperature Active Region Loops
Pulse-beam heating of deep atmospheric layers, their oscillations and shocks modulating the flare reconnection
A potential magnetic field calculator for solar physics applications using staggered grids
E and B polarizations from inhomogeneous and solar surface turbulence
Oscillations Accompanying a He I 10830 Å Negative Fare in a Solar Facula II. Response of the Transition Region and Corona
Flare reconnection-driven magnetic field and Lorentz force variations at the Sun's surface
Why Does the Solar Corona Abnormally Rotate Faster Than the Photosphere?
Impacts On Proton Fluxes Observed During Different Interplanetary Conditions
Coronal Loop Seismology Using Standing Kink Oscillations With a Lookup Table
Data-Optimized Coronal Field Model: I. Proof of Concept
Coronal Bright Points

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