Analysis of the Orion-Eridanus Superbubble’s X-ray Emission Using HaloSat

Stellar winds and supernovae from the nearby (~400 pc) Orion OB association have sculpted the large scale Orion-Eridanus Superbubble out of the interstellar medium. The superbubble is characterized by shells of neutral and ionized gas, and by its hot (~10­⁶ K) interior that is bright in soft X-rays. We tiled the extent of the superbubble with over a dozen HaloSat observation fields, near 100 square degrees each, to observe X-rays in the energy range 0.4-7.0 keV. We used XSPEC to fit the resulting X-ray spectra with models of thermal plasma emission. The X-ray spectra are best fit by multiple plasma components of different temperatures and absorptions and provide accurate measurements of the superbubble’s interior temperature. We discuss a physical interpretation of the results in terms of the bubble and the hot galactic halo.