Observations of Enhanced EUV Continua During An X-Class Solar Flare Using SDO/EVE

Abstract

Observations of extreme-ultraviolet (EUV) emission from an X-class solar flare that occurred on 2011 February 15 at 01:44 UT are presented, obtained using the EUV Variability Experiment (EVE) onboard the Solar Dynamics Observatory. The complete EVE spectral range covers the free-bound continua of H I (Lyman continuum), He I, and He II, with recombination edges at 91.2, 50.4, and 22.8 nm, respectively. By fitting the wavelength ranges blue-ward of each recombination edge with an exponential function, lightcurves of each of the integrated continua were generated over the course of the flare, as well as emission from the free-free continuum (6.5-37 nm). The He II 30.4 nm and Lyman-alpha 121.6 nm lines, and soft X-ray (0.1-0.8 nm) emission from GOES are also included for comparison. Each free-bound continuum was found to have a rapid rise phase at the flare onset similar to that seen in the 25-50 keV lightcurves from RHESSI, suggesting that they were formed by recombination with free electrons in the chromosphere. However, the free-free emission exhibited a slower rise phase seen also in the soft X-ray emission from GOES, implying a predominantly coronal origin. By integrating over the entire flare the total energy emitted via each process was determined. We find that the flare energy in the EVE spectral range amounts to at most a few per cent of the total flare energy, but EVE gives us a first comprehensive look at these diagnostically important continuum components.

6 pages, 3 figures, 1 table. Accepted to ApJ Letters

References in corpus (2)

• Observational Evidence for Gentle Chromospheric Evaporation During the Impulsive Phase of a Solar Flare
• Observations of a solar flare and filament eruption in Lyman alpha and X-rays

Cited by in corpus (36)

• Time-Resolved Properties and Global Trends in dMe Flares from Simultaneous Photometry and Spectra
• Quasi-periodic pulsations in solar and stellar flares: an overview of recent results
• The Radiated Energy Budget of Chromospheric Plasma in a Major Solar Flare Deduced From Multi-Wavelength Observations
• Hydrogen Balmer Continuum in Solar Flares Detected by the Interface Region Imaging Spectrograph (IRIS)
• Measurements of Absolute Abundances in Solar Flares
• Physical Properties of White-Light Sources in the 2011 Feb 15 Solar Flare
• The spectral content of SDO/AIA 1600 and 1700 Å filters from flare and plage observations
• Extreme Ultra-Violet Spectroscopy of the Lower Solar Atmosphere During Solar Flares
• Flare Ribbon Energetics in the Early Phase of an SDO Flare
• The Magnetic Field of Active Region 11158 During the 2011 February 12-17 Flares : Differences between Photospheric Extrapolation and Coronal Forward-Fitting Methods
• Detection of 3-Minute Oscillations in Full-Disk Ly$\alpha$ Emission During A Solar Flare
• Lyman-alpha Variability During Solar Flares Over Solar Cycle 24 Using GOES-15/EUVS-E
• Time-Dependent Density Diagnostics of Solar Flare Plasmas Using SDO/EVE
• Observations of Thermal Flare Plasma with the EUV Variability Experiment
• Production of the Extreme-Ultraviolet Late Phase of an X Class Flare in a Three-Stage Magnetic Reconnection Process
• Radiative hydrodynamic modelling and observations of the X-class solar flare on 2011 March 9
• Quasi-periodic pulsation detected in Lyman-alpha emission during solar flares
• Thermodynamic Spectrum of Solar Flares Based on SDO/EVE Observations: Techniques and Statistical Results
• The Anomalous Temporal Behaviour of Broadband Ly$\alpha$ Emission During Solar Flares From SDO/EVE
• Extremely Large Extreme-ultraviolet Late Phase Powered by Intense Early Heating in a Non-eruptive Solar Flare
• Continuum Contributions to the SDO/AIA Passbands During Solar Flares
• Solar Flare Impulsive Phase Emission Observed with SDO/EVE
• Charge-exchange limits on low-energy alpha-particle fluxes in solar flares
• The Lyman-alpha Emission in Solar Flares. I. a Statistical Study on Its Relationship with the 1--8 Å Soft X-ray Emission
• Empirical relations between the intensities of Lyman lines of H and He${}^{+}$
• Energy Partition in Four Confined Circular-Ribbon Flares
• Signatures of Helium continuum in cool flare loops observed by SDO/AIA
• Global energetics of solar powerful events on 6 September 2017
• Lyman Continuum Observations of Solar Flares Using SDO/EVE
• Formation Of The Lyman Continuum During Solar Flares
• The Lyman-$\alpha$ Emission in a C1.4 Solar Flare Observed by the Extreme Ultraviolet Imager aboard Solar Orbiter
• Solar cycle observations of the Neon abundance in the Sun-as-a-star
• On the variation of the scaling exponent of the flare fluence with temperature
• Dynamics of plasma heating and energy distributions of accelerated electrons during solar flares based on X-ray and ultraviolet emission
• EUV Irradiance Observations from SDO/EVE as a Diagnostic of Solar Flares
• Quasi-Periodic Pulsations Detected in Ly$\alpha$ and Nonthermal Emissions During Solar Flares