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HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0109

Prediction of the EUV Helium line intensities in the solar atmosphere

plan term




 name : Giunta, Fludra    e-mail : Alessandra.Giunta[at]stfc.ac.uk

contact person in HINODE team

 name : Culhane    e-mail : jlc[at]mssl.ucl.ac.uk

 abstract of observational proposal
The study of helium line formation in the EUV solar spectrum can provide understanding of the physics of the lower transition region. Helium is one of the few elements that exhibits strong emission lines formed in the upper chromosphere/lower transition region and it is the second most abundant element in the Sun. However, analysing helium lines in the solar atmosphere is a particular challenging task, because of their optical thickness and the unusual behaviour of their intensities. Such a study requires spatially and spectrally resolved observations in the EUV range as well as sophisticated atomic modelling. The work focuses on to what extent differential emission measure (D.E.M.) distributions can reproduce the observed fluxes of the He I and He II lines, as observed by the Hinode/EIS and SoHO/CDS. It will also examine what is the mechanism that enhances the helium line intensities compared to other transition region lines.

 request to SOT

 request to XRT

 request to EIS
Slits:  ・1×256 arc sec2  ・2×256 arc sec2
Raster area: ・ 60×256 arc sec2
Emission lines:
・ Helium line: 256.3A.
・Lines for co-alignment between instruments: O V 184.1 A, O V 192.9 A, Si VII 275.3 A, Si VII 275.7 A, O IV 279.6 A, O IV 279.9 A.
・ Lines at high temperature (for D.E.M. analysis): Fe X 184.5 Å, Fe XII 186.9 A, Fe VIII 186.6 A, Fe XI 192.8 A, Fe XII 193.5 A, Fe XVI 262.9 A.

The following rasters have been submitted for validation:
Data rate: 12 kbits/s
Data volume: 32 Mbits
Cadence: 44 minutes, 20 seconds

Data rate: 23 kbits/s
Data volume: 16 Mbits
Cadence: 11 minutes, 51 seconds

 other participating instruments

・Active regions on disk (preferably within +-5 arcmin from disk centre, but other disk locations will also be acceptable).
・ Quiet Sun near disk center.

Duration of observations:
Two observing dates, on April 17 (probably between 12:00-16:00 UT, TBC soon by SUMER) and April 27, 20:00 − 24:00 UT

On each date, the preferred target will be an active region, but quiet sun will be observed if no active region available.
Active region (4 hours):
Raster: ral_he_int_2slit, repeat at least 10 times (2 hours), point to bright transition region emission or strong magnetic field concentrations (but preferably not sunspot) (apply solar rotation tracking)
Raster: ral_he_int_1slit, repeat 3 times (2 hours). Point to the same area where the previous ral_he_int_2slit raster finished, continue tracking solar rotation.

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