The source of unusual coronal upflows with photospheric abundance in a solar active region^⋆

¹ PMOD/WRC, Dorfstrasse 33, 7260 Davos, Switzerland
e-mail: louise.harra@pmodwrc.ch
² ETH Zürich, Institute for Particle Physics and Astrophysics, Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland
³ Instituto de Astronomía y Física del Espacio (IAFE), CONICET-UBA, Buenos Aires, Argentina
⁴ College of Science, George Mason University, 4400 University Drive, Fairfax, VA 22030, USA
⁵ NASA Goddard Space Flight Center, 8800 Greenbelt Rd, Greenbelt, MD 20771, USA
⁶ Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
⁷ NASA Marshall Space Flight Center, 4600 Rideout Rd SW, Bldg 4200, Huntsville, AL 35812-0001, USA
⁸ NSO, 3665 Discovery Dr, Fl 3, Boulder, CO 80303, USA
⁹ Solar-Terrestrial Centre of Excellence – SIDC, Royal Observatory of Belgium, Ringlaan, Av. Circulaire 3, 1180 Uccle, Belgium
¹⁰ Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale, rue Jean Teillac, 91405 Orsay, France
¹¹ UCL-Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
¹² Skobeltsyn Institute of Nuclear Physics, Moscow State University, Ulitsa Kolmogorova 1c2, 119992 Moscow, Russia

Received: 21 December 2022
Accepted: 8 May 2023

Abstract

Context. Upflows in the corona are of importance, as they may contribute to the solar wind. There has been considerable interest in upflows from active regions (ARs). The coronal upflows that are seen at the edges of active regions have coronal elemental composition and can contribute to the slow solar wind. The sources of the upflows have been challenging to determine because they may be multiple, and the spatial resolution of previous observations is not yet high enough.

Aims. In this article, we analyse coronal upflows in AR 12960 that are unusually close to the sunspot umbra. We analyse their properties, and we attempt to determine if it is possible that they feed into the slow solar wind.

Methods. We analysed the activity in the upflow region in detail using a combination of Solar Orbiter EUV images at high spatial and temporal resolution, Hinode/EUV Imaging Spectrometer data, and observations from instruments on board the Solar Dynamics Observatory. This combined dataset was acquired during the first Solar Orbiter perihelion of the science phase, which provided a spatial resolution of 356 km for two pixels. Doppler velocity, density, and plasma composition determinations, as well as coronal magnetic field modelling, were carried out to understand the source of the upflows.

Results. We observed small magnetic fragments, called moving magnetic features (MMFs), moving away from the sunspot in the active region. Specifically, they moved towards the sunspot from the edge of the penumbra where a small positive polarity connects to the umbra via small-scale and very dynamic coronal loops. At this location, small dark grains are evident and flow along penumbral filaments in continuum images. The magnetic field modelling showed small low-lying loops anchored close to the umbral magnetic field. The high-resolution data of the Solar Orbiter EUV Imagers showed the dynamics of these small loops, which last on time scales of only minutes. The edges of these small loops are the location of the coronal upflow that has photospheric abundance.