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HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0205

Line Shift vs. Temperature with Estimate of Absolute Velocity: Joint Observation with SUMER

plan term


@ @


 name : Teriaca, Dadashi @  e-mail : teriaca[at]mps.mpg.de

contact person in HINODE team

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

 abstract of observational proposal
Following observations in earlier SUMER campaigns, a short joint SUMER/EIS observation is proposed for the period 4th to 8th July when SUMER will be briefly operational.

In 2007, during the first campaign, SUMER and EIS observations of the quiet Sun were made to determine the average Doppler shift vs. temperature up to 2 MK. Before the launch of Hinode and the possibility of recording coronal line profiles with high spectral resolution with EIS, our knowledge was limited to temperatures up to 1 MK. At this temperature modest blueshifts of few km/s are observed, in contrast to the substantial redshifts, up to 10 km/s observed in the transition region. The extension to higher temperatures and the determination of whether increasing blueshifts or a return towards zero velocities is observed, allows us to probe the bulk of the coronal emission and, thus, to provide an important global observable to be matched by models of the solar corona (e.g., the 3-D models developed by Hansteen et al. 2010).

This study is based on a new technique to obtain absolute velocities by combining the on-disk observations with off-limb data and with calibrated SUMER spectra of at least one coronal line. Above the limb, in areas without prominent loops or prominences, mass flows are expected to cancel out on average. Thus, off-limb spectra can be used to determine the wavelength separation at rest between spectral lines and a line assumed as reference. Then, the measurement of the same quantities on the disk and the knowledge of the average velocity of the ion forming the reference line, allow a reliable and robust determination of the absolute Doppler velocity in all the observed EIS lines. SUMER spectra, for which a wavelength calibration is possible (see, e.g., Teriaca et al. 1999), provide the absolute Doppler velocity of the Mg X line at 62.5 nm that is taken as proxy of the Doppler velocity in EIS lines from Fe X.

This work is part of the PhD thesis of Neda Dadashi, supervised by Teriaca and Solanki at MPS in Katlenburg-Lindau.  A paper on this topic has been submitted to A&A and the referee responses are expected shortly.

As a next step in this project we would like to repeat the observations and related analysis for a full active region.  Although a possible active area was also observed briefly in April 2007, assessment of this second dataset suggests that the activity level was so low that the region could at best be considered to be a slightly active part of the Quiet Sun. We are, therefore, seeking a joint EIS/SUMER observation for an approximately four hour slot to observe an AR, preferably close to disk centre, to enable good velocity measurements. Two already existing EIS studies have been selected that would be suitable for this observation.

 request to SOT

 request to XRT

 request to EIS
The study for AR on disk:

EIS Study #471
TARGET:           Active Region
RASTER:           Scanning
SLIT:             1"
STEP SIZE:        2"
FOV:              360"x512"

The study for OFF LIMB:

EIS study #111
TARGET            Off limb
RASTER:           Sit & Stare
SLIT:             1"
WINDOW HEIGHT (pixels): 200

 other participating instruments


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