Article

Small-scale H alpha jets in the solar chromosphere

Aims. High temporal and spatial resolution observations from the Rapid Oscillations in the Solar Atmosphere (ROSA) multiwavelength imager on the Dunn Solar Telescope are used to study the velocities of small-scale H? jets in an emerging solar active region. Methods. The dataset comprises simultaneous imaging in the H? core, Ca ii K, and G band, together with photospheric line-of-sight magnetograms. Time-distance techniques are employed to determine projected plane-of-sky velocities. Results. The H? images are highly dynamic in nature, with estimated jet velocities as high as 45 km s?1. These jets are one-directional, with their origin seemingly linked to underlying Ca ii K brightenings and G-band magnetic bright points. Conclusions. It is suggested that the siphon flow model of cool coronal loops is suitable for interpreting our observations. The jets are associated with small-scale explosive events, and may provide a mass outflow from the photosphere to the corona.

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