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Solar spicules are small-scale, beam-like, cold-plasma-ejected phenomena that constitute an important component of the chromosphere. Macrospicules are chromospheric spicules at a larger spatial scale.

The study of macrospicules will help us understand the driving mechanism of the spicules because the triggering process of macrospicules in observation is easily resolved by modern high-resolution solar observation equipment.

Recently, researchers from the Yunnan Observatories of the Chinese Academy of Sciences and their collaborators from Yunnan University used the chromosphere high-resolution telescope from the New Vacuum Solar Telescope to study the detailed evolution process of the base of the macrospicules.

The study was published in The Astrophysical Journal Letters on Jan. 6.

The researchers found that before the launch of each macrospicule, a compact bright patch (BP) was detected at its base where a newly emerging dipole contacts and cancel with the preexisting ambient field.

The spectral diagnosis from the Interface Region Imaging Spectrograph at one of BPs revealed signatures of reconnection at the lower atmosphere. They suggested that the macrospicules and related BPs formed in a common reconnection process, in which the increasing reconnection height between the emerging dipole and the ambient field resulted in the observed variations from BPs to macrospicules.

The researchers concluded that the formation mechanism of macrospicules should be the same as spicules and coronal jets, i.e., solar jetting phenomena at different scales share the same physical mechanism in association with magnetic reconnection.

This work provided clear observational evidence that the macrospicules originated from magnetic reconnection in the lower solar atmosphere, and provided new clues for understanding the driving mechanism of spicules.