Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Chromospheric cannonballs on the Sun   In the highly dynamic chromosphere, there exist many kinds of small-scale
activities, such as spicules, surges, and Ellerman bombs. Here, we report the
discovery of a new phenomenon in the chromosphere observed with the New Vacuum
Solar Telescope at the Fuxian Solar Observatory. In the high tempo-spatial
resolution H$\alpha$ images, some dark or bright structures are found to fly
along the curved trajectory, looking like cannonballs. Their average size,
mass, and velocity are about 1.5 $\times$ 10$^{9}$ km$^{3}$, 1.5 $\times$
10$^{8}$ kg, and 56 km s$^{-1}$, respectively. In the simultaneous
(extreme-)ultraviolet images obtained by the Solar Dynamics Observatory, these
cannonballs appear as brighter features compared to the surrounding area,
implying that there exists some kind of heating during this process. The
photospheric magnetograms show the magnetic flux emergence and interaction with
the pre-existing fields. These observations reveal that the cannonballs are
chromospheric material blobs launched due to the magnetic reconnection between
emerging magnetic flux and the pre-existing loops.

31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
16
The categories of this paper are: stat
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
8
The categories of this paper are: hep-ex
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
12
The categories of this paper are: nucl-th