Flare lines in Hinode EIS spectra

Zanna, G. Del

doi:10.1051/0004-6361:20079033

Cited by 50 publications

(43 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Evidence was found in a number of cases (Del Zanna 2008a;Del Zanna & Ishikawa 2009) for lines around 250 Å having significantly lower intensities than expected. It is obviously important to attempt measurements of electron temperatures which are independent of any assumption of ionization equilibrium.…”

Section: Discussionmentioning

confidence: 80%

Benchmarking atomic data for astrophysics: Fe VIII EUV lines

Zanna¹

2009

A&A

Self Cite

View full text Add to dashboard Cite

The EUV spectrum of Fe viii is reviewed, using new solar observations from the Hinode EUV Imaging Spectrometer (EIS), together with older solar and laboratory data. The most up-to-date scattering calculations are benchmarked against these experimental data, with the use of a large atomic structure calculation. Once adjustments are made to the excitation rates, good agreement is found between calculated and observed line intensities. All previous line identifications have been re-assessed. Several lines are identified here for the first time, most notably the strong decays from the 3s 2 3p 5 3d 2 4 D j levels. It is shown that they provide a new, important diagnostic of electron temperature for the upper transition region. The temperatures obtained at the base of solar coronal loops are lower (log T [K] = 5.5) than those predicted by assuming ionization equilibrium (log T [K] = 5.6), however firm measurements will only be possible once better scattering calculations are available, and the EIS radiometric calibration is properly assessed.

show abstract

Section: Discussionmentioning

confidence: 80%

Benchmarking atomic data for astrophysics: Fe VIII EUV lines

Zanna¹

2009

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…In the analysis section of this Letter, we have illustrated that the combined Hinode XRT and EIS data set has a blind spot (Del Zanna 2008;Del Zanna et al 2011). The response curves of a few of the broadband XRT filters are shown in the middle panel of Figure 3.…”

Section: Discussionmentioning

confidence: 93%

DEFINING THE “BLIND SPOT” OF HINODE EIS AND XRT TEMPERATURE MEASUREMENTS

Winebarger

Warren

Schmelz

et al. 2012

ApJ

View full text Add to dashboard Cite

Observing high-temperature, low emission measure plasma is key to unlocking the coronal heating problem. With current instrumentation, a combination of EUV spectral data from Hinode Extreme-ultraviolet Imaging Spectrometer (EIS; sensitive to temperatures up to 4 MK) and broadband filter data from Hinode X-ray Telescope (XRT; sensitive to higher temperatures) is typically used to diagnose the temperature structure of the observed plasma. In this Letter, we demonstrate that a "blind spot" exists in temperature-emission measure space for combined Hinode EIS and XRT observations. For a typical active region core with significant emission at 3-4 MK, Hinode EIS and XRT are insensitive to plasma with temperatures greater than ∼6 MK and emission measures less than ∼10 27 cm −5 . We then demonstrate that the temperature and emission measure limits of this blind spot depend upon the temperature distribution of the plasma along the line of sight by considering a hypothetical emission measure distribution sharply peaked at 1 MK. For this emission measure distribution, we find that EIS and XRT are insensitive to plasma with emission measures less than ∼10 26 cm −5 . We suggest that a spatially and spectrally resolved 6-24 Å spectrum would improve the sensitivity to these high-temperature, low emission measure plasma.

show abstract

“…In this paper, we discuss which EIS spectral lines we found most useful for studies of small flares, and which lines are particularly problematic because of blending (for a discussion of other flare lines, see Del Zanna 2008a;and Del Zanna & Ishikawa 2009). These considerations should be taken into account in future studies which use the EIS instrument.…”

Section: Discussionmentioning

confidence: 99%

The 22 May 2007 B-class flare: new insights fromHinodeobservations

Zanna¹,

Mitra-Kraev²,

Bradshaw

et al. 2010

A&A

Self Cite

View full text Add to dashboard Cite

We present multi-wavelength observations of a small B-class flare which occurred on the Sun on 2007 May 22. The observations include data from Hinode, GOES, TRACE and the Nobeyama Radioheliograph. We obtained spatially and spectrally-resolved information from the Hinode EUV Imaging Spectrometer (EIS) during this event. The temporal and temperature coverage of the EIS observations provides new insights into our understanding of chromospheric evaporation and cooling. The flare showed many "typical" features, such as brightenings in the ribbons, hot (10 MK) loop emission and subsequent cooling. We also observed a new feature, strong (up to 170 km s −1 ) blue-shifted emission in lines formed around 2-3 MK, located at the footpoints of the 10 MK coronal emission and within the ribbons. Electron densities at 2 MK in the kernels are high, of the order of 10 11 cm −3 , suggesting a very narrow layer where the chromospheric evaporation occurs. We have run a non-equilibrium hydrodynamic numerical simulation using the HYDRAD code to study the cooling of the 10 MK plasma, finding good agreement between the predicted and observed temperatures, densities and ion populations. Line blending for some potentially useful diagnostic lines for flares, which are observed with Hinode/EIS, is also discussed.

show abstract

Flare lines in Hinode EIS spectra

Abstract: We aim to identify the brightest hot emission lines in Hinode EIS spectra, and suggest the best ones to be used in flare observations. The EIS database was searched in order to find suitable datasets to identify the prominent lines. A B2-class flare spectrum was found.

Cited by 50 publications

References 13 publications

Benchmarking atomic data for astrophysics: Fe VIII EUV lines

Benchmarking atomic data for astrophysics: Fe VIII EUV lines

DEFINING THE “BLIND SPOT” OF HINODE EIS AND XRT TEMPERATURE MEASUREMENTS

The 22 May 2007 B-class flare: new insights fromHinodeobservations

Contact Info

Product

Resources

About