HOP 0154

HOP No.

HOP title

HOP 0154

Coronal heating and connectivity between the transition region and coronal emission in active regions

abstract of observational proposal

Science goals: During our work on the coronal heating in active regions (Fludra and Ireland 2008; Fludra and Warren 2010 –submitted) we have found that the transition region emission in the O~V 62.9nm line is much more variable than the coronal emission, and has a different dependence on the magnetic field. High-resolution observations in coronal lines are needed simultaneously with observations of strong transition region lines to identify which OV emission originates at the footpoints of coronal loops. The remaining OV emission will be attributed to short loops that have no connection to the corona. The heating of these two categories of loops will be analysed separately.

How the objective will be achieved:
Hinode EIS observes a resonance line of He II at 256 Å, OV at 248.46 A and a number of strong coronal lines. This will be combined with SOHO/CDS observations of OV 62.9nm and He I 58.43nm. The co-alignment of CDS and EIS will be achieved through cross-correlating the He rasters. We therefore request simultaneous observations using SOHO/CDS and Hinode/EIS for several active region targets.

request to EIS

Study: cam_artb_rhessi_a_1 (already exists)
Slits: 2×256 arc sec2
Raster area: 240×240 arc sec2
Emission lines: 21 lines, including:
TR lines: He II 256.3 Å, OV 248.46 A
Lines at higher temperature: Fe VIII 185.12 Å, Fe XI 188.23 Å, Fe XII 195.12 Å, Fe XIII 202.04/203.83, Fe XVI 262.9 Å, Fe XXIII 263.76, Fe XIV 264.78/274.20, Mg VII 278.39/280.75, Fe XV 284.16.

The following existing study has been found suitable for this programme:

Cam_artb_rhessi_a_1
Data rate: 64.5 kbits/s
Data volume: 133 Mbits
Cadence: ~30 minutes (exposure time: 15 s)

In the future we will consider using JPEG90 compression to reduce the data volume by a factor of 2.

remarks

Targets: Active regions on disk (preferably within +-5 arcmin from disk centre). Limb locations are not suitable.

Duration of observations:
Active region (1 - 2 hours):
Raster: cam_artb_rhessi_a_1, repeat up to 2 times at the same pointing on a smaller region, or run at two adjacent locations in a large active region. Point above bright transition region emission or strong magnetic field concentrations (but preferably not sunspot). If possible, repeat this sequence on the same target several hours later.

Please run on several active regions as available (can be run on different days). Alternatively, run on the same region on two or three consecutive days. Please notify cdsplanner@grace.nascom.nasa.gov in advance of scheduling this study.