The Thermally Unstable Solar Atmosphere
The solar atmosphere is a strongly coupled multi-layered and multi-scale system, linked together and regulated by the Sun’s magnetic field. The mass and energy circulation that result are not only at the core of coronal heating but also reflect the delicate thermal balance (or the absence of it) maintained by competition of heating and cooling processes. Increasing observational, theoretical, and numerical work suggests that a significant fraction of the solar atmosphere is in a state of thermal non-equilibrium (TNE) and thermal instability (TI). Such work also points to a significant role of TNE-TI as drivers of these mass and energy flows, which manifests in the increased dynamics and filamentary structure of the corona observed in transition region lines, the formation of prominences and the pervasive coronal rain and EUV pulsation phenomena observed in the quiet Sun and active regions (quiescent and flaring). Indeed, recent large-scale numerical simulations with self-consistent corona formation with coronal rain show localized and intermittent UV brightening in the transition region and chromosphere due to coronal rain accretion, as well as EUV / UV strands and strong variability in the corona. This link is supported by Solar Orbiter / HRI and IRIS observations, where rain clumps (in EUV absorption) and the UV strands (in emission) are similar in width as the observed EUV strands. The showers composed of coronal rain clumps help identify coronal loops in the so-called coronal veil and provide an estimate of the coronal volume undergoing TNE-TI. Such high-resolution observations reveal a solar atmosphere where TNE-TI and its by-products such as coronal rain are prevalent. In this talk I will present and discuss the strong connection between the observed properties of hot and cool material in thermal non-equilibrium and instability, the insight we have gained from numerical modelling and new Solar Orbiter observations that show the extent of our thermally unstable solar atmosphere. If time permits I will also show interesting similarities with multiphase plasmas at much larger scales in the universe, in the circumgalactic (CGM), interstellar (ISM) and intra-cluster (ICM) media.
I am a Colombian and French solar physicist working at Northumbria University (Newcastle upon Tyne, UK). My research career has been a rollercoaster. My PhD studies were conducted in Kyoto (Japan) and Oslo (Norway), with Kazunari Shibata and Mats Carlsson, finalising them in 2012. I then moved to Leuven (Belgium) to work with Tom Van Doorsselaere and then back to Japan, this time to the University of Tokyo (to work with Takaaki Yokoyama) and then to NAOJ (Tokyo), where I worked with the Hinode team. Then, in 2016 I moved to Scotland where I worked with Ineke De Moortel before finally moving in 2019 to Newcastle with an STFC Ernest Rutherford Fellowship and Senior Lectureship at Northumbria University. I am particularly interested in observations and numerical simulations of events within the inner solar corona associated with coronal heating (e.g. MHD waves and magnetic reconnection) and cooling (coronal rain and prominences).