FIBRILLAR CHROMOSPHERIC SPICULE-LIKE COUNTERPARTS TO AN EXTREME-ULTRAVIOLET AND SOFT X-RAY BLOWOUT CORONAL JET

Abstract

We observe an erupting jet feature in a solar polar coronal hole, using data from Hinode/Solar Optical Telescope (SOT), Extreme Ultraviolet Imaging Spectrometer (EIS), and X-Ray Telescope (XRT), with supplemental data from STEREO/EUVI. From extreme-ultraviolet (EUV) and soft X-ray (SXR) images we identify the erupting feature as a blowout coronal jet: in SXRs it is a jet with a bright base, and in EUV it appears as an eruption of relatively cool (∼50,000 K) material of horizontal size scale ∼30'' originating from the base of the SXR jet. In SOT Ca ii H images, the most pronounced analog is a pair of thin (∼1'') ejections at the locations of either of the two legs of the erupting EUV jet. These Ca ii features eventually rise beyond 45'', leaving the SOT field of view, and have an appearance similar to standard spicules except that they are much taller. They have velocities similar to that of "type II" spicules, ∼100 km s−1, and they appear to have spicule-like substructures splitting off from them with horizontal velocity ∼50 km s−1, similar to the velocities of splitting spicules measured by Sterling et al. Motions of splitting features and of other substructures suggest that the macroscopic EUV jet is spinning or unwinding as it is ejected. This and earlier work suggest that a subpopulation of Ca ii type II spicules are the Ca ii manifestation of portions of larger scale erupting magnetic jets. A different subpopulation of type II spicules could be blowout jets occurring on a much smaller horizontal size scale than the event we observe here.