Research Interest on Heesu's Weblog

Periodic bursty ejections during a dome-spire-shaped jet

Tue, 01 Sep 2026 00:00:00 +0000

Spectroscopic observations of periodic bursty ejections during a dome-spire-shaped jet

The study investigates the complexity of the formation and evolution of a dome-spire-shaped jet (or anemone jet) presumably driven by null-point magnetic reconnection.

SOLARIS-Hα

Tue, 01 Sep 2026 00:00:00 +0000

Solar Dynamic Hα Integral Field Spectrometer

SOMSPECT2

Mon, 02 Feb 2026 00:00:00 +0000

Solar Coronal Multi-slit Spectro-polarimeteric Telescope

Challan Telescope

Fri, 08 Aug 2025 00:00:00 +0000

The Korean word ‘Challan’ refers to something brilliant, radiant, or glorious, and is often used to describe dazzling light or magnificent beauty. The name reflects the instrument’s ability to capture the Sun’s radiant features.

Hα dark blobs and transparent regions

Fri, 08 Aug 2025 00:00:00 +0000

We investigated three fan-shaped jets observed above sunspot light bridges or nearby sunspot regions. The study aimed to explore the dynamics and physical properties of jets’ features that appear as blob-like structures at the tips of the jets, which we call `dark blobs’. A transparent region is observed beneath the dark blobs, creating a visible gap between the dark blobs and the trailing body of the jets. These phenomena were studied in chromospheric and transition region imaging and spectral high-resolution co-observations from the Visible Imaging Spectrometer of the Goode Solar Telescope at the Big Bear Solar Observatory and the Interface Region Imaging Spectrograph (IRIS), together with data from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. We analyzed the jets’ morphology and fine structure. We obtained the spatial scale and the dynamics of the dark blobs that are seen mostly in the wings of the H$\alpha$ line and have a cross-section of about 0.2\asc$-$0.3\asc. The dark blobs and the transparent regions are seen bright (in emission) in the IRIS slit-jaw 1330~\AA, 1400~\AA, and AIA 304~\AA\ images. The IRIS Si~{\sc iv} 1394~\AA\ spectrum of the brightenings showed blue-shifted emission of about $16,$\kmps\ with non-thermal velocities of up to $40,$\kmps. We also estimated the electron density of the blue-shifted brightenings to be $10^{12.1\pm0.2}$,cm$^{-3}$. Our findings likely suggest that we detect the observational signatures of shock waves that generate and/or contribute to the evolution of fan-shaped jets.

Astronomical Instrumentation Education

Wed, 28 Feb 2024 00:00:00 +0000

The abilities of system engineering and project management (PM) are essential in the development of large instrumentations in modern astronomy. We propose a novel undergraduate educational program that allows students to gain experience in system engineering and PM by making a practical small spectrograph along with its test observation. A pilot program titled “Creative Astronomical Instrument Development and Observation” was conducted in Chungnam National University, as a part of the Space Expert Training Program of Ministry of Science and ICT during the Fall semester of 2023. After five teams were organized from 24 participating students, each team manufactured a spectrograph and observed spectra of the Sun, Moon, or planets with it. The development process was guided by several reviews, and students were evaluated based on the outcomes of their development processes and documentation. Through this program, students acquired fundamental principles of systems engineering and PM, as well as optical and mechanical engineering skills. (See more: https://doi.org/10.52912/jsta.2024.4.2.105 )

Measuring DOLP of the Solar F-Corona on the CODEX

Thu, 23 Mar 2023 00:00:00 +0000

One of the most unrevealed pieces of information about the solar F- corona is its polarization. We propose the possibility of measuring the degree of linear polarization (DF ) of the F-corona along the radial distance from the Sun using the signal of two filters installed on the COronal Diagnostic EXperiment (CODEX), which will be mounted on board the International Space Station in December 2023. By analyzing the signal and noise of CODEX with Monte- Carlo simulations, we can derive DF with a 1.4nm-width narrow bandpass filter centered at 393.55nm and a 10 nm-width broad bandpass filter centered at 393.5 nm, by stacking six images and integrating over 1 R⊙ ×1 R⊙. The DF measured by CODEX will help to reduce the uncertainty of the K-coronal polarization (pBK ), a main target of the mission, as well as to provide a better understanding of the F-corona. The result was published in Solar physics (See more: https://doi.org/10.1007/s11207-023-02147-0 )