tokens: soft X-ray emission towards the south loop. As suggested by Snowden et al. (1995) , we find that significant 0.25 keV emission remains inside the loop after the foreground emission from the Local Bubble and the background intensity are subtracted. The background intensity is the intensity that is expected from the Galactic halo and is modulated by the total gas absorption. Taking the south loop absorption into account, we find no clear spectral difference between the EXE1 region north of the east shell and the EXE2 region towards the south loop. The spectral dichotomy that is visible on the maps is largely induced by the south loop absorption. A single-temperature plasma cannot match the X-ray spectra across the three bands in any of the sampled directions, however. Two hot phases are required, with respective temperatures of 3–9 MK and 0.3–1.2 MK under the assumption of a uniform pressure across both phases. The derived pressure of (3− 8) × 10 4 cm −3 K exceeds the pressure of the Local Bubble of 10 4 cm −3 K ( Puspitarini et al. 2014 ). The need for at least two plasma phases might indicate global plasma oscillations across the superbubble that are caused by its complex interior history ( Krause et al. 2014 ). In addition, the significant emission hardening seen towards the region that is enclosed between the H α arcs A and B corresponds to a higher pressure and hotter temperature that support the hypothesis of a younger age and faster expansion of this sub-region ( Heiles et al. 1999 ). The origin of the south loop ring is unclear. A wind-blown bubble seems unlikely because of the lack of massive stars in this direction ( Burrows et al. 1993 ). We find no gradient in temperature or pressure between the south loop and adjacent regions that would support a cooling flow of hot gas that leaks at the rear of the superbubble ( Heiles et al. 1999 ). The gas ring, filled with plasma that is a few million degrees hot, is consistent with an old supernova remnant. The progenitor star may have belonged to the Cassiopeia-Taurus OB association, which extends from 130 to 300 pc ( de Zeeuw et al. 1999 ; Pellizza et al. 2005 ) in these directions. The more sensitive and refined X-ray maps that will soon be obtained by the extended Roentgen survey with an imaging telescope array (e-ROSITA) will spatially and spectrally constrain the heterogeneity of the hot gas phases that fill the superbubble better. This will enable us to reconstruct the possible sequence of supernovae that have blown this structure. 6.3 Magnetic field in the superbubble We have used Planck polarised dust emission and the gas dynamics information from the H I line decomposition to study the magnetic field in the superbubble. We probed the plane-of-sky magnetic field, B sky , using the modified Davis–Chandrasekhar–Fermi method (DCF method) proposed by Cho Yoo (2016) . We have obtained magnetic strengths 17 times lower than previous estimates along the west rim ( Soler et al. 2018 ). The
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