Scientific Justification * We organize an observing campaign to build a holistic view of the solar source coronal hole of the high-speed solar wind stream seen by Parker Solar Probe (PSP) at its 8th perihelion on April 29th. This campaign will address the following questions:
- Where are the individual open magnetic funnels which build the coronal hole rooted?
- How is mass transported from the photosphere to the corona in these funnels? - How does the outflow velocity and mass flux in the lower corona in coronal holes depend on the properties of the open magnetic funnels in lower atmospheric heights?
- How do the solar wind properties seen by PSP depend on the properties of its source coronal hole?
- How does the associated high-speed solar wind stream evolve from the Sun to 0.9 AU as seen by Solar Orbiter and 1.5 AU as seen by Maven?
The time window around Parker Solar Probe’s (PSPs) 8th perihelion provides a unique opportunity to address these questions, as the perihelion is observable from Earth view, as it takes place end of April where usually the observing conditions for the ground-based telescopes in Tenerife are good, and as Solar Orbiter and Maven are well aligned with PSP. The observing campaign will be 10 days, i.e., from April 28th to May 7th , with an observing time of roughly 4.5 hours per day.
We received SOLARNET observing time for the ground-based high-resolution spectropolarimetric instruments SST/CHRISP and GREGOR/GRIS. They will probe and create magnetic field maps from the photosphere to the upper chromosphere in 4 heights, which shall allow us to uniquely identify the open magnetic funnels in coronal holes. Here, we request IRIS and Hinode for observations of the transition region and corona to study the plasma outflow velocity, temperature, density, mass flux, and FIP abundances in multiple heights.
The IRIS and Hinode observations during these 10 days shall be performed in two setups:
・Setup #1: detailed scans over entire coronal holes at multiple days, in order to study the distribution of magnetic funnels and their statistical properties, and their long-term evolution.
・Setup #2: high-cadence scans of subregions of coronal holes at the other days, in order to study the short-term evolution and upward propagating waves from the photosphere to the low corona.
In order to maximize the output of this observing campaign, we coordinate this observing campaign with the Whole Heliosphere and Planetary Interaction (WHPI) initiative, and expect that further ground-based optical and radio observatories join the effort. To ease the collaboration, all of the data taken shall be publicly released immediately after the observations. This proposal covers Setup #1 of the campaign.