DUAN Yadan, SHEN Yuandeng from Yunnan Observatories, Chinese Academy of Sciences (CAS), and their co-authors CHEN Hechao from Yunnan University, reported an interesting study on the macrospicules and their connection to magnetic reconnection in the lower solar atmosphere. The result was recently published in The Astrophysical Journal Letters.

Solar spicules are small scale beam-like cold plasma ejected phenomena in the chromosphere, which are an important component of the chromosphere. Studying the mechanism of spicules and their potential contribution to coronal heating has been a frontier scientific problem in international solar physics research. Resolving the detailed triggering and driving processes of spicules at their bases is still difficult, since these key processes occur at a small scale close to or below the highest spatial resolution of most current instruments. Therefore, the origin mechanism of spicules is still an open question although some candidate scenarios have been proposed.

The 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 solar high-resolution observation equipment.

For the first time, the researchers used the chromosphere high-resolution telescope from the New Vacuum Solar Telescope to study the detailed evolution process of the base of the macrospicules. Before the launch of each macrospicule, they detected a compact bright patch (BP) at its base. The spectral diagnosis from the Interface Region Imaging Spectrograph at one of BPs reveals signatures of reconnection at the lower atmosphere. They suggested that the macrospicules and related BPs form in a common reconnection process, in which the increasing reconnection height between the emerging dipole and the ambient field results in the observed variations from BPs to macrospicules. In addition, they 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 important new clues for understanding the driving mechanism of the spicules.

Contact:
SHEN Yuandeng
Yunnan Observatories, CAS
Email: ydshen@ynao.ac.cn