MHD waves in the solar atmosphere
Erwin Verwichte, University of Warwick
The Sun is the our nearest star and the only one that directly affects the Earth on a daily basis. Its light and heat keeps our planet habitable, but its space weather activity challenges our technology and journey into deep space. We study the solar atmosphere to understand the physical processes that underlie this activity, and that manifests itself through flares, coronal mass ejections, equatorial coronal holes,…
But we also study the Sun because it is only star we can examine in exquisite spatially resolved detail and reveal the stellar processes responsible for the activity cycle, the transport of mass and heat through the chromosphere, heat deposition in the higher atmosphere and the acceleration of the solar wind. We use plasma physics and magnetohydrodynamics (MHD) The magnetically dominated corona also shares much of the physics that is found in magnetically confined fusion experiments.
Magnetohydrodynamic (MHD) waves are prevalent throughout the solar atmosphere and play pivotal roles in the aforementioned processes. I will introduce how the various types of MHD waves manifest themselves at the Sun, illustrated by examples from modern ground-based and space-born observations. In particular, I will focus on studies of waves in thermally active plasmas, both at hot and cool temperatures, that are directly linked to flaring.
I will show how waves can provide insight into magnetic reconnection underlying flares as well as into thermal instabilities that are part of the atmospheric mass cycle.
Supernova Imposter Syndrome: Eruptions of Massive Stars
Jen Andrews, University of Arizona
Existing in the magnitude space between traditional supernovae (SNe) and classical novae lies a zoo of explosive and eruptive transients with maximum absolute magnitudes of MV between -10 and -15.
Traditionally interpreted as giant luminous blue variable (LBV) eruptions these often dubbed “SN imposters” likely arise from a variety of initial stellar masses and are caused by physical mechanisms ranging from instabilities in nuclear burning as the object
evolves off the main sequence to stellar mergers in binary star systems. Moreover, some individual LBV giant eruptions, including the prototypical case of Eta Car, have been proposed as massive-star merger events. All of these involve large amounts of episodic
mass loss, and many of them share observed properties that blur the distinction between categories. While their eruptions mimic those of SNe, these transients appear to all be non-terminal, leaving some form of the progenitor behind after eruption. I will
discuss this class of non-terminal transients, including the Great Eruption of the enigmatic Eta Car and a uniquely puzzling SN imposter in M74.