Comparison of Solar X-Ray Line Emission with Microwave Emission during Flares

Neupert, W. M.

doi:10.1086/180220

Cited by 782 publications

(515 citation statements)

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“…The hot material is seen in soft X-ray and extreme ultraviolet emissions, where the light curves are more gradual, with a slower increase than the impulsive emission and a much longer, exponential decay. The impulsive and gradual emissions are often temporally connected through the "Neupert effect" relation (Neupert 1968;Dennis & Zarro 1993)…”

Section: Introductionmentioning

confidence: 99%

Relationship between X-ray and ultraviolet emission of flares from dMe stars observed by XMM-Newton

Mitra-Kraev¹,

Harra²,

Güdel

et al. 2005

A&A

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Abstract. We present simultaneous ultraviolet and X-ray observations of the dMe-type flaring stars AT Mic, AU Mic, EV Lac, UV Cet and YZ CMi obtained with the XMM-Newton observatory. During 40 h of simultaneous observation we identify 13 flares which occurred in both wave bands. For the first time, a correlation between X-ray and ultraviolet flux for stellar flares has been observed. We find power-law relationships between these two wavelength bands for the flare luminosity increase, as well as for flare energies, with power-law exponents between 1 and 2. We also observe a correlation between the ultraviolet flare energy and the X-ray luminosity increase, which is in agreement with the Neupert effect and demonstrates that chromospheric evaporation is taking place.

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Section: Introductionmentioning

confidence: 99%

Relationship between X-ray and ultraviolet emission of flares from dMe stars observed by XMM-Newton

Mitra-Kraev¹,

Harra²,

Güdel

et al. 2005

A&A

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“…The UMASEP scheme considers that a common positive derivative with the particle flux near Earth, with a suitable time delay, indicates a magnetic connection between the Earth and a site of particle acceleration near the Sun. It is well known (Neupert 1968;Dennis and Zarro 1993;Holman et al 2011) that hard X-ray (HXR) or microwave bursts, produced by non-thermal electrons in the solar atmosphere through bremsstrahlung and gyrosynchrotron emission (see Chap. 2), have time profiles that mimic the time derivative of the SXR.…”

Section: Predicting Sep Event Onsets From Historical Microwave Data Bmentioning

confidence: 99%

HESPERIA Forecasting Tools: Real-Time and Post-Event

Núñez¹,

Klein²,

Heber³

et al. 2017

Astrophysics and Space Science Library

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Within the HESPERIA Horizon 2020 project, two novel real-time tools to predict Solar Energetic Particle (SEP) events were developed. The HESPERIA UMASEP-500 tool makes real-time predictions using a lag-correlation between the soft X-ray (SXR) flux and high-energy differential proton fluxes of the GOES satellite network. We found that the use of proton data alone allowed this tool to make predictions before any Neutron Monitor (NM) station's alert. The performance of this tool for predicting Ground Level Enhancement (GLE) events for the period 2000-2016 may be summarized as follows: the probability of detection (POD) was 53.8%, the false alarm ratio (FAR) was 30%, and the average warning time (AWT) to the first NM station's alert was 8 min. The developed HESPERIA REleASE tool makes real-time predictions of the proton flux-time profiles of 30-50 MeV protons at L1 and is based on electron intensity measurements of energies from 0.25 to 1 MeV and their intensity changes. The performance was tested by using all historic ACE/EPAM and SOHO/EPHIN data from 2009 until 2016 and has shown that the forecast tools have a low FAR ( 30%) and a high POD (63%). Furthermore, two methods using historical data were explored for predicting SEP events and M. Núñez ( ) • P. Reyes-Santiago

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“…Moreover, we take the derivative of the SXR flux as proportional to the HXR flux, referring to the so-called "Neupert effect" (Neupert 1968). Looking for an increase in the HXR flux, we have estimated the beginning of the impulsive phase, which occurs at 08:37:51 UT.…”

Section: Impulsive and Early Gradual Phasementioning

confidence: 99%

A MULTI-INSTRUMENT ANALYSIS OF a C4.1 FLARE OCCURRING IN a Δ SUNSPOT

Guglielmino¹,

Zuccarello²,

Romano

et al. 2016

ApJ

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We present an analysis of multi-instrument space-and ground-based observations relevant to a C4.1 solar flare that occurred in the active region (AR) NOAA 11267 on 2011 August 6. Solar Dynamics Observatoryobservations indicate that at the flare's beginning, it was localized in the preceding sunspot of the AR, which exhibits a δ configuration. Along the polarity inversion line between its opposite polarities we find a large shear angle of about 80°. The helicity accumulation shows that the AR does not obey the general hemispheric helicity rule. At the flare peak, unique observations taken with the X-Ray Telescope aboard Hinode reveal that the bulk of the X-ray emission takes place in the δ-spot region, where the plasma heats up to 1.9 10 7 · » K. During the gradual phase, we observe the development of a Y-shaped structure in the corona and in the high chromosphere. An extruding structure forms, being directed from the emitting region above the δ spot toward the following sunspot. This structure cools down in a few tens of minutes while moving eastward along a direction opposite to the flare ribbon expansion. Finally, remote brightenings are found at the easternmost footpoint of this structure, appearing as a third flare ribbon in the chromosphere. After some minutes, RHESSI measurements show that the X-ray emission is localized in the region close to the crossing point of the coronal Y-shaped structure. Simultaneously, highresolution (0 15) observations performed at the Swedish 1 m Solar Telescope indicate a decreasing trend of the Ca II H intensity in the flare ribbons with some transient enhancements. All these findings suggest that this event is a manifestation of magnetic reconnection, likely induced by an asymmetric magnetic configuration in a highly sheared region.

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Comparison of Solar X-Ray Line Emission with Microwave Emission during Flares

Cited by 782 publications

References 0 publications

Relationship between X-ray and ultraviolet emission of flares from dMe stars observed by XMM-Newton

Relationship between X-ray and ultraviolet emission of flares from dMe stars observed by XMM-Newton

HESPERIA Forecasting Tools: Real-Time and Post-Event

A MULTI-INSTRUMENT ANALYSIS OF a C4.1 FLARE OCCURRING IN a Δ SUNSPOT

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