HOP 0249

abstract of observational proposal

Objective: To determine the thermal evolution and wave properties in spicules

Scientific Background:
Hinode and ground-based observations of spicules have indicated the presense of vigorous Alfvenic waves, and suggest that these ubiquitous features play an important role in the energy and mass balance of the outer solar atmosphere. Both swaying and torsional motions with significant amplitudes have been observed on chromospheric spicules (De Pontieu et al., 2007, Okamoto et al., 2011, De Pontieu et al., 2012) . In addition, coordinated studies of SOT, EIS and SDO/AIA (De Pontieu et al., 2009, De Pontieu et al., 2011) suggest that spicules often disappear from chromospheric passbands because they are rapidly heated to TR and coronal temperatures. However, the detailed thermal evolution and wave propagation has been difficult to determine because of their rapid evolution on small spatial scales, and lack of coverage in transition region passbands. Coordinated observing with IRIS now provides excellent coverage in the upper chromosphere and transition region at high spatial, temporal and spectral resolution, which will allow us to address the energy budget, propagation and dissipation of Alfvenic waves, and the thermal evolution of spicules. These are crucial for a better theoretical understanding and/or modeling of these ubiquitous jets.

request to SOT

Ca II H at 4.8s cadence with exposure times long (~1.5s or more, but avoid saturation on the disk) and field-of-view as wide as possible, and including both disk and the off-limb regions (at least 25 arcsec off the limb should be visible at all times). For example, Program 0x3fd (or a modified version with 4.8 sec cadence) can be used with ROI 3 set to shift the FOV so it is centered on the limb: ROI shift 27 arcsec N or S for N or S polar pointing, 27 arcsec W for W limb pointing.

other participating instruments

Request to IRIS:

Six different observing modes:

A. Sit-and-stare with 8s exposure times, and both 2796/1400 slit-jaws (for total SJI cadence of ~20s)

B. Sit-and-stare with 8s exposure times, and 1330/1400 slit-jaws

C. Sit-and-stare with 8s exposure times, and 2796/1330 slit-jaws

D. Sit-and-stare with 4s exposure times, and 1330/2796/1400 slit-jaws (SJI cadence of ~18s)

E. Sit-and-stare with 4s exposure times, and 1330/1400 slit-jaws (SJI cadence of ~10s)

F. Two-step raster with 8s exposure times, and 2796/1400 slit-jaws (SJI cadence of ~20s)

These should all have linelist 0, non-simultaneous read-out (OBS-ID > 50) and run for at least 1 hour.

Each program should be run at least three times, for different roll angles so that the slit is perpendicular to the limb, at an angle of ~45 deg and parallel to the limb. The runs with the slit parallel to the limb should be done at 5 arcsec off limb, 10 arcsec, and 15 arcsec.

remarks

Minimum duration of each run should be 1 hour, avoiding SAA; longer runs are desirable when telemetry allows.

The target should be the limb in quiet Sun, coronal hole (if available at the limb) and active region. Note that the SOT FOV is internally shifted, independent of the usual SOT offset that is well-known to CPs and COs. THEREFORE, HINODE POINTING (corrected for the usual SOT offset) SHOULD AIM 20-25 ARCSEC INSIDE OF THE LIMB AT AT THE TARGET POSITION PLANNED FOR IRIS.

The target coordinates could be chosen either by the Hinode or IRIS planners, depending on the phase of the Hinode planning cycle. If the SAA-free periods are not used, then coordination between the planners to avoid SAA in both spacecraft is necessary. IRIS SAA-free times are approximately 11-15 UT and 23 - 04 UT.