Magnetic fields inferred by Solar Orbiter: A comparison between SO/PHI-HRT and SDO/HMI

Context. The High Resolution Telescope (HRT) of the Polarimetric and Helioseismic Imager on board the Solar Orbiter spacecraft (SO/PHI) and the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) both infer the photospheric magnetic field from polarised light images. SO/PHI is the first magnetograph to move out of the Sun–Earth line and will provide unprecedented access to the Sun’s poles. This provides excellent opportunities for new research wherein the magnetic field maps from both instruments are used simultaneously. Aims. We aim to compare the magnetic field maps from these two instruments and discuss any possible differences between them. Methods. We used data from both instruments obtained during Solar Orbiter’s inferior conjunction on 7 March 2022. The HRT data were additionally treated for geometric distortion and degraded to the same resolution as HMI. The HMI data were re-projected to correct for the 3° separation between the two observatories. Results. SO/PHI-HRT and HMI produce remarkably similar line-of-sight magnetograms, with a slope coefficient of 0.97, an offset below 1 G, and a Pearson correlation coefficient of 0.97. However, SO/PHI-HRT infers weaker line-of-sight fields for the strongest fields. As for the vector magnetic field, SO/PHI-HRT was compared to both the 720-second and 90-second HMI vector magnetic field: SO/PHI-HRT has a closer alignment with the 90-second HMI vector. In the weak signal regime (< 600 G), SO/PHI-HRT measures stronger and more horizontal fields than HMI, very likely due to the greater noise in the SO/PHI-HRT data. In the strong field regime (≳600 G), HRT infers lower field strengths but with similar inclinations (a slope of 0.92) and azimuths (a slope of 1.02). The slope values are from the comparison with the HMI 90-second vector. Possible reasons for the differences found between SO/PHI-HRT and HMI magnetic field parameters are discussed.Sección Deptal. de Óptica (Óptica)Fac. de Óptica y OptometríaTRUEBMWi - Bundesministerium für Wirtschaft und Energie (Alemania)AEI/MCIN/10.13039/501100011033Ministerio de ciencia e innovación de EspañaInstituto Astrofísico de Andalucía (España)Agencia Estatal de Investigación (España)Fondo Europeo de Desarrollo Regional (Fondos FEDER)Centre national d'études spatiales (CNES) (Francia)CSIC (Centro Superior de Investigaciones Científicas) (España)pu

Slow Solar Wind Connection Science during Solar Orbiter’s First Close Perihelion Passage

The Slow Solar Wind Connection Solar Orbiter Observing Plan (Slow Wind SOOP) was developed to utilize the extensive suite of remote-sensing and in situ instruments on board the ESA/NASA Solar Orbiter mission to answer significant outstanding questions regarding the origin and formation of the slow solar wind. The Slow Wind SOOP was designed to link remote-sensing and in situ measurements of slow wind originating at open–closed magnetic field boundaries. The SOOP ran just prior to Solar Orbiter’s first close perihelion passage during two remote-sensing windows (RSW1 and RSW2) between 2022 March 3–6 and 2022 March 17–22, while Solar Orbiter was at respective heliocentric distances of 0.55–0.51 and 0.38–0.34 au from the Sun. Coordinated observation campaigns were also conducted by Hinode and IRIS. The magnetic connectivity tool was used, along with low-latency in situ data and full-disk remote-sensing observations, to guide the target pointing of Solar Orbiter. Solar Orbiter targeted an active region complex during RSW1, the boundary of a coronal hole, and the periphery of a decayed active region during RSW2. Postobservation analysis using the magnetic connectivity tool, along with in situ measurements from MAG and SWA/PAS, showed that slow solar wind originating from two out of three of the target regions arrived at the spacecraft with velocities between ∼210 and 600 km s−1. The Slow Wind SOOP, despite presenting many challenges, was very successful, providing a blueprint for planning future observation campaigns that rely on the magnetic connectivity of Solar Orbiter

The on-ground data reduction and calibration pipeline for SO/PHI-HRT

Software and Cyberinfrastructure for Astronomy VII (2022), Montreal, Jul 17-22, 2022.--Proceedings of SPIE - The International Society for Optical Engineering vol. 12189 Article number 121891J.-- Full list of authors: Sinjan, J.; Calchetti, D.; Hirzberger, J.; Orozco Suárez, D.; Albert, K.; Albelo Jorge, N.; Appourchaux, T.; Alvarez-Herrero, A.; Blanco Rodríguez, J.; Gandorfer, A.; Germerott, D.; Guerrero, L.; Gutierrez Marquez, P.; Kahil, F.; Kolleck, M.; Solanki, S. K.; del Toro Iniesta, J. C.; Volkmer, R.; Woch, J.; Fiethe, B.; Gómez Cama, J. M.; Pérez-Grande, I.; Sanchis Kilders, E.; Balaguer Jiménez, M.; Bellot Rubio, L. R.; Carmona, M.; Deutsch, W.; Fernandez-Rico, G.; Fernández-Medina, A.; García Parejo, P.; Gasent Blesa, J. L.; Gizon, L.; Grauf, B.; Heerlein, K.; Korpi-Lagg, A.; Lange, T.; López Jiménez, A.; Maue, T.; Meller, R.; Michalik, H.; Moreno Vacas, A.; Müller, R.; Nakai, E.; Schmidt, W.; Schou, J.; Schühle, U.; Staub, J.; Strecker, H.; Torralbo, I.; Valori, G.The ESA/NASA Solar Orbiter space mission has been successfully launched in February 2020. Onboard is the Polarimetric and Helioseismic Imager (SO/PHI), which has two telescopes, a High Resolution Telescope (HRT) and the Full Disc Telescope (FDT). The instrument is designed to infer the photospheric magnetic field and line-of-sight velocity through differential imaging of the polarised light emitted by the Sun. It calculates the full Stokes vector at 6 wavelength positions at the Fe I 617.3nm absorption line. Due to telemetry constraints, the instrument nominally processes these Stokes profiles onboard, however when telemetry is available, the raw images are downlinked and reduced on ground. Here the architecture of the on-ground pipeline for HRT is presented, which also offers additional corrections not currently available on board the instrument. The pipeline can reduce raw images to the full Stokes vector with a polarimetric sensitivity of 10-3 · Ic or better. © COPYRIGHT SPIE.This work was carried out in the framework of the International Max Planck Research School (IMPRS) for Solar System Science at the Max Planck Institute for Solar System Research (MPS). Solar Orbiter is a space mission of international collaboration between ESA and NASA, operated by ESA. We are grateful to the ESA SOC and MOC teams for their support. The German contribution to SO/PHI is funded by the BMWi through DLR and by MPG central funds. The Spanish contribution is funded by FEDER/AEI/MCIU (RTI2018-096886-C5), a "Center of Excellence Severo Ochoa" award to IAA-CSIC (SEV-2017-0709), and a Ram ' on y Cajal fellowship awarded to DOS. The French contribution is funded by CNES.Peer reviewe

Magnetospheric Venus Space Explorers (MVSE) Mission: A Proposal for Understanding the Dynamics of Induced Magnetospheres

soumis a Acta AstronauticaInduced magnetospheres form around planetary bodies with atmospheres through the interactionof the solar wind with their ionosphere. Induced magnetospheres are highly dependent on the so-lar wind conditions and have only been studied with single spacecraft missions in the past. Thisgap in knowledge could be addressed by a multi-spacecraft plasma mission, optimized for study-ing global spatial and temporal variations in the magnetospheric system around Venus, whichhosts the most prominent example of an induced magnetosphere in our solar system. The MVSEmission comprises four satellites, of which three are identical scientific spacecraft, carrying thesame suite of instruments probing different regions of the induced magnetosphere and the solarwind simultaneously. The fourth spacecraft is the transfer vehicle which acts as a relay satellitefor communications at Venus. In this way, changes in the solar wind conditions and extremesolar events can be observed, and their effects can be quantified as they propagate through theVenusian induced magnetosphere. Additionally, energy transfer in the Venusian induced mag-netosphere can be investigated. The scientific payload includes instrumentation to measure themagnetic field, electric field, and ion-electron velocity distributions. This study presents thescientific motivation for the mission as well as requirements and the resulting mission design.Concretely, a mission timeline along with a complete spacecraft design, including mass, power,communication, propulsion and thermal budgets are given. This mission was initially conceivedat the Alpbach Summer School 2022 and refined during a week-long study at ESA’s ConcurrentDesign Facility in Redu, Belgiu

Magnetospheric Venus Space Explorers (MVSE) Mission: A Proposal for Understanding the Dynamics of Induced Magnetospheres

soumis a Acta AstronauticaInduced magnetospheres form around planetary bodies with atmospheres through the interactionof the solar wind with their ionosphere. Induced magnetospheres are highly dependent on the so-lar wind conditions and have only been studied with single spacecraft missions in the past. Thisgap in knowledge could be addressed by a multi-spacecraft plasma mission, optimized for study-ing global spatial and temporal variations in the magnetospheric system around Venus, whichhosts the most prominent example of an induced magnetosphere in our solar system. The MVSEmission comprises four satellites, of which three are identical scientific spacecraft, carrying thesame suite of instruments probing different regions of the induced magnetosphere and the solarwind simultaneously. The fourth spacecraft is the transfer vehicle which acts as a relay satellitefor communications at Venus. In this way, changes in the solar wind conditions and extremesolar events can be observed, and their effects can be quantified as they propagate through theVenusian induced magnetosphere. Additionally, energy transfer in the Venusian induced mag-netosphere can be investigated. The scientific payload includes instrumentation to measure themagnetic field, electric field, and ion-electron velocity distributions. This study presents thescientific motivation for the mission as well as requirements and the resulting mission design.Concretely, a mission timeline along with a complete spacecraft design, including mass, power,communication, propulsion and thermal budgets are given. This mission was initially conceivedat the Alpbach Summer School 2022 and refined during a week-long study at ESA’s ConcurrentDesign Facility in Redu, Belgiu

Magnetospheric Venus Space Explorers (MVSE) Mission: A Proposal for Understanding the Dynamics of Induced Magnetospheres

soumis a Acta AstronauticaInduced magnetospheres form around planetary bodies with atmospheres through the interactionof the solar wind with their ionosphere. Induced magnetospheres are highly dependent on the so-lar wind conditions and have only been studied with single spacecraft missions in the past. Thisgap in knowledge could be addressed by a multi-spacecraft plasma mission, optimized for study-ing global spatial and temporal variations in the magnetospheric system around Venus, whichhosts the most prominent example of an induced magnetosphere in our solar system. The MVSEmission comprises four satellites, of which three are identical scientific spacecraft, carrying thesame suite of instruments probing different regions of the induced magnetosphere and the solarwind simultaneously. The fourth spacecraft is the transfer vehicle which acts as a relay satellitefor communications at Venus. In this way, changes in the solar wind conditions and extremesolar events can be observed, and their effects can be quantified as they propagate through theVenusian induced magnetosphere. Additionally, energy transfer in the Venusian induced mag-netosphere can be investigated. The scientific payload includes instrumentation to measure themagnetic field, electric field, and ion-electron velocity distributions. This study presents thescientific motivation for the mission as well as requirements and the resulting mission design.Concretely, a mission timeline along with a complete spacecraft design, including mass, power,communication, propulsion and thermal budgets are given. This mission was initially conceivedat the Alpbach Summer School 2022 and refined during a week-long study at ESA’s ConcurrentDesign Facility in Redu, Belgiu

The on-ground data reduction and calibration pipeline for SO/PHI-HRT

The ESA/NASA Solar Orbiter space mission has been successfully launched in February 2020. Onboard is the Polarimetric and Helioseismic Imager (SO/PHI), which has two telescopes, a High Resolution Telescope (HRT) and the Full Disc Telescope (FDT). The instrument is designed to infer the photospheric magnetic field and line-of-sight velocity through differential imaging of the polarised light emitted by the Sun. It calculates the full Stokes vector at 6 wavelength positions at the Fe I 617.3 nm absorption line. Due to telemetry constraints, the instrument nominally processes these Stokes profiles onboard, however when telemetry is available, the raw images are downlinked and reduced on ground. Here the architecture of the on-ground pipeline for HRT is presented, which also offers additional corrections not currently available on board the instrument. The pipeline can reduce raw images to the full Stokes vector with a polarimetric sensitivity of 10−3⋅Ic or better.Sección Deptal. de Óptica (Óptica)Fac. de Óptica y OptometríaTRUEBMWi - Bundesministerium für Wirtschaft und Energie (Alemania)MPG - Max-Planck-Gesellschaft (Alemania)Ministerio de Ciencia e Innovación de España - MCIUInstituto de Astrofísica de Andalucía - CSIC (España)CNES - Centre National d'études spatiales (Francia)Fondos FEDERAgencia Estatal de Investigación - AEI (ESpaña)pu

Slow Solar Wind Connection Science during Solar Orbiter’s First Close Perihelion Passage

The Slow Solar Wind Connection Solar Orbiter Observing Plan (Slow Wind SOOP) was developed to utilize the extensive suite of remote-sensing and in situ instruments on board the ESA/NASA Solar Orbiter mission to answer significant outstanding questions regarding the origin and formation of the slow solar wind. The Slow Wind SOOP was designed to link remote-sensing and in situ measurements of slow wind originating at open–closed magnetic field boundaries. The SOOP ran just prior to Solar Orbiter’s first close perihelion passage during two remote-sensing windows (RSW1 and RSW2) between 2022 March 3–6 and 2022 March 17–22, while Solar Orbiter was at respective heliocentric distances of 0.55–0.51 and 0.38–0.34 au from the Sun. Coordinated observation campaigns were also conducted by Hinode and IRIS. The magnetic connectivity tool was used, along with low-latency in situ data and full-disk remote-sensing observations, to guide the target pointing of Solar Orbiter. Solar Orbiter targeted an active region complex during RSW1, the boundary of a coronal hole, and the periphery of a decayed active region during RSW2. Postobservation analysis using the magnetic connectivity tool, along with in situ measurements from MAG and SWA/PAS, showed that slow solar wind originating from two out of three of the target regions arrived at the spacecraft with velocities between ∼210 and 600 km s ^−1 . The Slow Wind SOOP, despite presenting many challenges, was very successful, providing a blueprint for planning future observation campaigns that rely on the magnetic connectivity of Solar Orbiter

Firefly: The Case for a Holistic Understanding of the Global Structure and Dynamics of the Sun and the Heliosphere

This white paper is on the HMCS Firefly mission concept study. Firefly focuses on the global structure and dynamics of the Sun's interior, the generation of solar magnetic fields, the deciphering of the solar cycle, the conditions leading to the explosive activity, and the structure and dynamics of the corona as it drives the heliosphere