HOP 0330

abstract of observational proposal

Main Objectives:
We aim to constrain the heating mechanisms in both the magnetically quiet and magnetically dominated (plage) chromosphere of the Sun by obtaining coordinated ALMA, Hinode and IRIS observations and comparing those with synthetic observations of advanced numerical models.

Scientific Justification:
We will focus on the dynamics of the chromospheric heating in the internetwork and in plage regions, so need high-cadence observations with Hinode/SP and IRIS to study the impact of granular fields on both environments. In the internetwork we aim to capture the shocks that permeate that region and obtain an estimate of the minimum temperatures reached. Comparison of ALMA observations with Hinode/SP, IRIS and numerical simulations will constrain the lowest temperatures and provide insight into the role of ambipolar diffusion in these cold regions.
In plage, we aim to better understand how the chromospheric heating (from IRIS and ALMA) is related to the magnetic field, both the kG fields and the weaker, granular scale fields.

request to SOT

Fast Hinode/SP rasters with a cadence of maximum 80s. Readout along the slit should be at least 60 arcsec. FOV perpendicular to the slit should be densely covered. The program can be very similar to that of HOP 243: SP: very fast maps, to obtain the required time resolution with enough slit positions to maximize the chance of overlap with the IRIS slit. Both sides of the CCD are used to increase SNR.

Two programs have been tested so far:

SP 0x15b Very Fast Map, 9"x82", 2-side CCD, Q65, repeats: cadence = 73 sec, telemetry usage = 500 Mbits/hour

SP 0x190 HOP 243 low-TLM, Very Fast map 9x82, lower half

For a plage target observed with IRIS, use either
SP 0x0194 HOP 243 Plage, DynamicsMode 9x82, bottom half, uses ~1000 Mbits/hr
SP 0x0195 HOP 243 Plage, Lower-TLM DynMode, 9x82, bottom half, uses ~500 Mbits/hr

other participating instruments

IRIS:
3620502035 | Medium dense 16-step raster 5x60 16s Deep x 0.5 FUV spectrally rebi | 26.33 | 53.96 | 1.4 | 1.6+/-0.1 | 26.4+/-0.1 | 13.2+/-0.0 | 13.2+/-0.0 | 13.2+/-0.0 | 13.2+/-0.0

remarks

Dates:
Our observations have been scheduled to occur at ALMA somewhere from Dec 8 through Dec 28.

Time window:
We have asked for two periods of 1 hour with ALMA. We require IRIS to NOT be in eclipse during this time. Detailed scheduling will be done by the ALMA folks and the HOP PI.

Target(s) of interest:
Plage, ideally not too far from disk center, but we'll take whatever the Sun gives us. If plage is unavailable, strong network regions are fine too. The Hinode/SP slit should also cover some neighboring quiet Sun.

Previous HOP information:
HOP 236:
Vissers et al. 2015, ApJ, 812
Skogsrud et al. 2015, ApJ, 806, 170
Martinez-Sykora et al. 2015, ApJ, 803, 44
Rouppe van der Voort et al. 2015, ApJ, 799, 3
Skogsrud, Rouppe van der Voort, & De Pontieu 2014, ApJ, 795, 23
Hansteen et al. 2014, Science, 346, 1255757
De Pontieu et al. 2014, Science, 346, 1255732