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Welcome to Myungkook James Jee's Homepage


Name in Korean: 지명국
Position: Professor
Address: Department of Astronomy, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul
Ph.D: Johns Hopkins University, 2005
Research interests: Gravitational Lensing, Cosmology, Galaxy Clusters, Large Scale Structure, Deep Learning, and Astronomical Instrumentation

James leads YOUNG (Yonsei Observable UNiverse Group).

ADS publication list Visit google scholar

Science Highlights Featured in NASA NASA-Logo.jpg news

(01/05/2023) Ancient Ghost Light -ORPHANED STARS WERE LOST INTO INTERGALACTIC SPACE LONG AGO In the 1960s sci-fi television show "Lost in Space" a small family of would-be planetary colonists get off course and lost in our galaxy. But truth is stranger than fiction when it comes to Hubble Space Telescope discoveries. Thanks to Hubble, astronomers now know about entire families of stars – and presumably their planetary systems – that don't even have a galaxy to call home. We are nestled inside the sprawling Milky Way galaxy, an empire of stars. But there are many stars wandering about inside giant clusters of hundreds or thousands of galaxies. These stars are not gravitationally tied to any one galaxy in a cluster. Read details.

Paper link: Intracluster light is already abundant at redshift beyond unity (Joo & Jee 2023)

(01/06/2017) Double Whammy -Astronomers have discovered what happens when the eruption from a supermassive black hole is swept up by the collision and merger of two galaxy clusters. This composite image contains X-rays from Chandra (blue), radio emission from the GMRT (red), and optical data from Subaru (red, green, and blue) of the colliding galaxy clusters called Abell 3411 and Abell 3412. These and other telescopes were used to analyze how the combination of these two powerful phenomena can create an extraordinary cosmic particle accelerator. Read details.

Paper link: The case for electron re-acceleration at galaxy cluster shocks (van Weeren et al. 2017)

(12/18/2014) il Gioiello Cluster -A newly discovered galaxy cluster is the most massive one ever detected with an age of 800 million years or younger. Using data from NASA's Chandra X-ray Observatory, astronomers have accurately determined the mass and other properties of this cluster, as described in our latest press release. This is an important step in understanding how galaxy clusters, the largest structures in the Universe held together by gravity, have evolved over time. Read details.

Paper link: CHANDRA DEEP OBSERVATION OF XDCP J0044.0-2033, A MASSIVE GALAXY CLUSTER AT z > 1.5 (Tozzi et al. 2015)

El gordo.jpg

(04/04/2014) EL GORDO -If someone told you there was an object in space called "El Gordo" (Spanish for "the fat one") you might imagine some kind of planet-eating monster straight out of a science fiction movie. The nickname refers to a monstrous cluster of galaxies that is being viewed at a time when the universe was just half of its current age of 13.8 billion years Read details.

Paper link: (Jee et al. 2014)


(03/02/2012) Cosmic Train Wreck - Astronomers observed what appeared to be a clump of dark matter left behind during a bizarre wreck between massive clusters of galaxies. The dark matter collected into a "dark core" containing far fewer galaxies than would be expected if the dark matter and galaxies hung together. Read details.

Paper link: (Jee et al. 2012)


(05/15/2007) Hubble Finds Ghostly Ring of Dark Matter - The most common substance in the universe is called dark matter. It doesn’t shine or reflect light. We can’t even see it. Astronomers using NASA’s Hubble Space Telescope got a first-hand view of how dark matter behaves during a titanic collision between two galaxy clusters. The wreck created a ripple of dark matter, which is somewhat similar to a ripple formed in a pond when a rock hits the water. Read details.

Paper link: (Jee et al. 2007)

Current projects

LSST logo.jpg

Vera Rubin Telescope Legacy Survey of Space and Time (LSST)- The Rubin observatory, currently under construction in Chile, is designed to conduct a ten-year survey of the dynamic universe. LSST will scan the entire visible sky in just a few nights; each panoramic snapshot with the 3200-megapixel camera covers an area 40 times the size of the full moon. LSST will map the structure of the Milky Way and the large-scale structure of the universe and address the nature of dark matter and dark matter.


Merging Cluster Project- Cluster mergers are the most energetic events since the Big Bang. We use cluster mergers to study the large-scale structure evolution, particle acceleration, and dark matter based on multi-wavelength observations and numerical simulations.