Chromospheric flashes in a solar pore: insights from multiline spectropolarimetric diagnostics

Solar pores are strongly magnetized regions without a photospheric penumbra, with predominantly vertical magnetic fields. We present a multiline investigation of flashes in a pore using high-resolution Swedish Solar Telescope observations in Fe I 6302, Ca II (λ8542 and K), and Hβ, complemented with (extreme-)UV observations from the Interface Region Imaging Spectrograph and Solar Dynamics Observatory. Complementary to bisector analysis, spectral inversions with the Stokes Inversion based on Response functions (SIR) code and Non-LTE Inversion Code using the Lorien Engine (NICOLE) provided temperature, line-of-sight velocity, and magnetic field stratifications. Flashes, confined to the left half of the pore, exhibited cooler temperatures (ΔT ≈ 400 K), stronger magnetic fields (ΔB ≈ 250 G), greater inclination (∼25° vs. ∼18°), and persistent upflows (∼0.5 km s−1) relative to the quiescent pore in the photosphere. Flashes were cospatial with enhanced 3- and 5-minute power in the photosphere, with only 3-minute power persisting in the chromosphere. Flashes were seen up to 50% line depth in Ca II λ8542 intensity, but not below, and showed central upflows (∼1 km s−1, 1″–2″) flanked by strong downflows (∼8 km s−1) in the chromosphere. Associated temperature enhancements reached ∼500 K at log τ ≈ −5 and ∼2500 K at log τ ≈ −6. Flash spectra displayed a bimodal velocity distribution, with ∼52% showing downflows at log τ ≈ −5. Flashes corresponded one to one with radially outward-propagating running waves (5–15 km s−1, amplitude ∼1 km s−1) near the pore boundary. Spectral diagnostics revealed strong Ca II (λ8542 and K) core emission, occasional Stokes V reversals, and broadband Hβ enhancements. The results suggest that pore flashes are confined to the lower and mid-chromosphere, with little influence on the transition region or corona.