Reconstruction of total solar irradiance variability as simultaneously apparent from Solar Orbiter and Solar Dynamics Observatory

• Published in: Astronomy and astrophysics (Berlin) 2023-11, Vol.679, p.A25
• Main Authors: Yeo, K. L., Krivova, N. A., Solanki, S. K., Hirzberger, J., Orozco Suárez, D., Albert, K., Albelo Jorge, N., Appourchaux, T., Alvarez-Herrero, A., Blanco Rodríguez, J., Gandorfer, A., Gutierrez-Marques, P., Kahil, F., Kolleck, M., del Toro Iniesta, J. C., Volkmer, R., Woch, J., Fiethe, B., Pérez-Grande, I., Sanchis Kilders, E., Balaguer Jiménez, M., Bellot Rubio, L. R., Calchetti, D., Carmona, M., Feller, A., Fernandez-Rico, G., Fernández-Medina, A., García Parejo, P., Gasent Blesa, J. L., Gizon, L., Grauf, B., Heerlein, K., Korpi-Lagg, A., Maue, T., Meller, R., Moreno Vacas, A., Müller, R., Nakai, E., Schmidt, W., Schou, J., Sinjan, J., Staub, J., Strecker, H., Torralbo, I., Valori, G.
• Format: Article
• Language: English
• Subjects: Cool stars; Ecliptic; Helioseismology; Irradiance; Observatories; Photosphere; Reconstruction; Solar activity; Solar observatories; Stellar rotation
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361/202345872

Solar irradiance variability has been monitored almost exclusively from the Earth’s perspective. We present a method to combine the unprecedented observations of the photospheric magnetic field and continuum intensity from outside the Sun-Earth line, which is being recorded by the Polarimetric and Helioseismic Imager on board the Solar Orbiter mission (SO/PHI), with solar observations recorded from the Earth’s perspective to examine the solar irradiance variability from both perspectives simultaneously. Taking SO/PHI magnetograms and continuum intensity images from the cruise phase of the Solar Orbiter mission and concurrent observations from the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory (SDO/HMI) as input into the SATIRE-S model, we successfully reconstructed the total solar irradiance variability as apparent from both perspectives. In later stages of the SO mission, the orbital plane will tilt in such a way as to bring the spacecraft away from the ecliptic to heliographic latitudes of up to 33°. The current study sets the template for the reconstruction of solar irradiance variability as seen from outside the ecliptic from data that SO/PHI is expected to collect from such positions. Such a reconstruction will be beneficial to factoring inclination into how the brightness variations of the Sun compare to those of other cool stars, whose rotation axes are randomly inclined.