30 research outputs found
A complex solar coronal jet with two phases
This work was partly supported by National Natural Science Foundation of China (grant Nos. 11303048, 11673033, 11373040, 11427901). This work was also partly supported by an International Exchanges cost share award with NSFC for overseas travel between collaborators in the UK and China, and State Key Laboratory for Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences.Jets often occur repeatedly from almost the same location. In this paper, a complex solar jet was observed with two phases to the west of NOAA AR 11513 on 2012 July 2. If it had been observed at only moderate resolution, the two phases and their points of origin would have been regarded as identical. However, at high resolution we find that the two phases merge into one another and the accompanying footpoint brightenings occur at different locations. The phases originate from different magnetic patches rather than being one phase originating from the same patch. Photospheric line of sight (LOS) magnetograms show that the bases of the two phases lie in two different patches of magnetic flux that decrease in size during the occurrence of the two phases. Based on these observations, we suggest that the driving mechanism of the two successive phases is magnetic cancellation of two separate magnetic fragments with an opposite-polarity fragment between them.Publisher PDFPeer reviewe
Heating of quiescent coronal loops caused by nearby eruptions observed with the Solar Dynamics Observatory and the Solar Upper Transition Region Imager
How structures, e.g., magnetic loops, in the upper atmosphere, i.e., the
transition region and corona, are heated and sustained is one of the major
unresolved issues in solar and stellar physics. Various theoretical and
observational studies on the heating of coronal loops have been undertaken. The
heating of quiescent loops caused by eruptions is, however, rarely observed. In
this study, employing data from the Solar Dynamics Observatory (SDO) and Solar
Upper Transition Region Imager (SUTRI), we report the heating of quiescent
loops associated with nearby eruptions. In active regions (ARs) 13092 and
13093, a long filament and a short filament, and their overlying loops are
observed on 2022 September 4. In AR 13093, a warm channel erupted toward the
northeast, whose material moved along its axis toward the northwest under the
long filament, turned to the west above the long filament, and divided into two
branches falling to the solar surface. Subsequently, the short filament erupted
toward the southeast. Associated with these two eruptions, the quiescent loops
overlying the long filament appeared in SDO/Atmospheric Imaging Assembly (AIA)
high-temperature images, indicating the heating of loops. During the heating,
signature of magnetic reconnection between loops is identified, including the
inflowing motions of loops, and the formation of X-type structures and newly
reconnected loops. The heated loops then cooled down. They appeared
sequentially in AIA and SUTRI lower-temperature images. All the results suggest
that the quiescent loops are heated by reconnection between loops caused by the
nearby warm channel and filament eruptions.Comment: 20 pages, 12 figures, accepted for publication in Ap
A Type II Radio Burst Driven by a Blowout Jet on the Sun
Type II radio bursts are often associated with coronal shocks that are
typically driven by coronal mass ejections (CMEs) from the Sun. Here, we
conduct a case study of a type II radio burst that is associated with a C4.5
class flare and a blowout jet, but without the presence of a CME. The blowout
jet is observed near the solar disk center in the extreme-ultraviolet (EUV)
passbands with different characteristic temperatures. Its evolution involves an
initial phase and an ejection phase with a velocity of 560 km/s. Ahead of the
jet front, an EUV wave propagates at a projected velocity of 403 km/s in the
initial stage. The moving velocity of the source region of the type II radio
burst is estimated to be 641 km/s, which corresponds to the shock velocity
against the coronal density gradient. The EUV wave and the type II radio burst
are closely related to the ejection of the blowout jet, suggesting that both
are likely the manifestation of a coronal shock driven by the ejection of the
blowout jet. The type II radio burst likely starts lower than those associated
with CMEs. The combination of the velocities of the radio burst and the EUV
wave yields a modified shock velocity at 757 km/s. The Alfven Mach number is in
the range of 1.09-1.18, implying that the shock velocity is 10%-20% larger than
the local Alfven velocity.Comment: Accepted by ApJ, 17 pages, and 6 figure
Observation of two splitting processes in a partial filament eruption on the sun: the role of breakout reconnection
Partial filament eruptions have often been observed, however, the physical
mechanisms that lead to filament splitting are not yet fully understood. In
this study, we present a unique event of a partial filament eruption that
undergoes two distinct splitting processes. The first process involves vertical
splitting and is accompanied by brightenings inside the filament, which may
result from internal magentic reconnection within the filament. Following the
first splitting process, the filament is separated into an upper part and a
lower part. Subsequently, the upper part undergoes a second splitting, which is
accompanied by a coronal blowout jet. An extrapolation of the coronal magnetic
field reveals a hyperbolic flux tube structure above the filament, indicating
the occurrence of breakout reconnection that reduces the constraning field
above. Consequently, the filament is lifted up, but at a nonuniform speed. The
high-speed part reaches the breakout current sheet to generate the blowout jet,
while the low-speed part falls back to the solar surface, resulting in the
second splitting. In addition, continuous brightenings are observed along the
flare ribbons, suggesting the occurrence of slipping reconnection process. This
study presents, for the first time, the unambiguous observation of a two-stage
filament splitting process, advancing our understanding of the complex dynamics
of solar eruptions.Comment: 12 pages, 8 figure
VisKoP: Visual Knowledge oriented Programming for Interactive Knowledge Base Question Answering
We present Visual Knowledge oriented Programming platform (VisKoP), a
knowledge base question answering (KBQA) system that integrates human into the
loop to edit and debug the knowledge base (KB) queries. VisKoP not only
provides a neural program induction module, which converts natural language
questions into knowledge oriented program language (KoPL), but also maps KoPL
programs into graphical elements. KoPL programs can be edited with simple
graphical operators, such as dragging to add knowledge operators and slot
filling to designate operator arguments. Moreover, VisKoP provides
auto-completion for its knowledge base schema and users can easily debug the
KoPL program by checking its intermediate results. To facilitate the practical
KBQA on a million-entity-level KB, we design a highly efficient KoPL execution
engine for the back-end. Experiment results show that VisKoP is highly
efficient and user interaction can fix a large portion of wrong KoPL programs
to acquire the correct answer. The VisKoP online demo
https://demoviskop.xlore.cn (Stable release of this paper) and
https://viskop.xlore.cn (Beta release with new features), highly efficient KoPL
engine https://pypi.org/project/kopl-engine, and screencast video
https://youtu.be/zAbJtxFPTXo are now publicly available
Where do flare ribbons stop?
The standard flare model, which was proposed based on observations and
magnetohydrodynamic theory, can successfully explain many observational
features of solar flares. However, this model is just a framework, with many
details awaiting to be filled in, including how reconnection is triggered. In
this paper, we address an unanswered question: where do flare ribbons stop?
With the data analysis of the 2003 May 29 flare event, we tentatively confirmed
our conjecture that flare ribbons finally stop at the intersection of
separatrices (or quasi-separatrix layer in a general case) with the solar
surface. Once verified, such a conjecture can be used to predict the final size
and even the lifetime of solar flares.Comment: 4 pages, 4 figures, to be published in Chinese Science Bulletin,
references are added, 2 figures are change
Solar Ring Mission: Building a Panorama of the Sun and Inner-heliosphere
Solar Ring (SOR) is a proposed space science mission to monitor and study the
Sun and inner heliosphere from a full 360{\deg} perspective in the ecliptic
plane. It will deploy three 120{\deg}-separated spacecraft on the 1-AU orbit.
The first spacecraft, S1, locates 30{\deg} upstream of the Earth, the second,
S2, 90{\deg} downstream, and the third, S3, completes the configuration. This
design with necessary science instruments, e.g., the Doppler-velocity and
vector magnetic field imager, wide-angle coronagraph, and in-situ instruments,
will allow us to establish many unprecedented capabilities: (1) provide
simultaneous Doppler-velocity observations of the whole solar surface to
understand the deep interior, (2) provide vector magnetograms of the whole
photosphere - the inner boundary of the solar atmosphere and heliosphere, (3)
provide the information of the whole lifetime evolution of solar featured
structures, and (4) provide the whole view of solar transients and space
weather in the inner heliosphere. With these capabilities, Solar Ring mission
aims to address outstanding questions about the origin of solar cycle, the
origin of solar eruptions and the origin of extreme space weather events. The
successful accomplishment of the mission will construct a panorama of the Sun
and inner-heliosphere, and therefore advance our understanding of the star and
the space environment that holds our life.Comment: 41 pages, 6 figures, 1 table, to be published in Advances in Space
Researc