Speaker
Description
First Name: Robin
Last Name: Colaninno
Email Address: robin.c.colaninno.civ@us.navy.mil
Affiliation: US Naval Research Laboratory
All Authors: Robin Colaninno, Philip Hess, Erika Palmerio, Eleni Nikou
Abstract: The transition between the solar corona and inner heliosphere presents a challenge for both physics and nomenclature. Historically, these two regions have been defined by their method of measurement: the solar corona is imaged using remote sensing instruments, while the heliosphere is sampled with in situ. Although the historic differences in measurement methods between the corona and inner heliosphere have been greatly reduced, a physical transition of the plasma environment from magnetically dominated to hydrodynamic occurs between the Sun and 1 AU. Magnetohydrodynamic (MHD) simulations primarily use a height of 20-30 R⊙ as the boundary between the magnetically dominated corona and the hydrodynamic heliosphere. The computational transition between coronal and heliospheric models is critical for propagating information from the solar-driven boundary conditions through the heliosphere to 1 AU through the model. We approach this critical region from a new perspective by combining MHD simulations with images from the Solar Orbiter Heliospheric Imager (SoloHI) to better understand the transition between coronal and heliospheric models. While SoloHI cannot provide direct, quantitative measurements of the plasma, it can be used to validate the shape, magnitude, and frequency of macro-scale transient structures in the solar wind. For this study, we exploit the 2024 April 8 solar eclipse period, known as the Great North American Eclipse, whose path of totality crossed most of the eastern United States. To complement the intensive ground-based observations of the solar corona made possible by the eclipse, extraordinary MHD modeling of the time period was performed. At the time of the eclipse, SoloHI was positioned in the heliosphere 96° East of the Sun-Earth line and looked back towards the Earth. The SoloHI observations provide a side view of this key transition region that has not yet been used to validate the models.