KMT-2022-BLG-1818Lb,c: A Cold Super-Jupiter with a Saturn Sibling

Abstract We present the discovery and analysis of the sixth microlensing two-planet system, KMT-2022-BLG-1818Lb,c, detected by a follow-up program targeting high-magnification events. The second planet was identified from implausible physical parameters for the models with a single planet. Both planets are subject to the well-known “close/wide” degeneracy, although for the first planet, which has a super-Jovian mass ratio of q 2 ≃ 5 × 10 −3 in both solutions, the close topology, with a normalized separation of s ≃ 0.70, is clearly preferred by Δ χ 2 = 26. However, contrary to all previous two-planet microlensing systems, the mass ratio for the second planet, q 3 , is substantially (factor of ∼10) different for the Close and Wide topologies of the first planet. While this degeneracy is resolved in the present case due to high-cadence follow-up observations, the appearance of this new degeneracy indicates the need for caution in the analysis of future two-planet systems. A Bayesian analysis suggests that the host is likely a K dwarf star in the Galactic disk. The first planet is probably a super-Jupiter on a Jupiter-like orbit, while the second planet is a Saturn-class planet on either a Mercury-like or Saturn-like orbit.

Authors

Publication Details

Journal
The Astronomical Journal
Published
2025-12-17
DOI
https://doi.org/10.3847/1538-3881/ae1b8f
Primary Topic
Stellar, planetary, and galactic studies
Type
article
Field-Weighted Citation Impact
0.00
Controls
|||
ALL TIME
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
article

KMT-2022-BLG-1818Lb,c: A Cold Super-Jupiter with a Saturn Sibling

Sang-Mok Cha, Yongseok Lee, I. Soszyński, Michael D. Albrow et al.
The Astronomical Journal
Stellar, planetary, and galactic studies
article

KMT-2022-BLG-1818Lb,c: A Cold Super-Jupiter with a Saturn Sibling

Sang-Mok Cha, Yongseok Lee, I. Soszyński, Michael D. Albrow, Weicheng Zang, Hongjing Yang, Yuki Satoh, Sean K. Terry, Daisuke Suzuki, J. McCormick, M. Gromadzki, Kyu‐Ha Hwang, Akihiko Fukui, Shude Mao, Hibiki Yama, ‪Clément Ranc, Subo Dong, Krzysztof A. Rybicki, D. P. Bennett, M. K. Szymański, J. Skowron, Byeong-Gon Park, R. Poleski, Yoon-Hyun Ryu, Wei Zhu, Zhuokai Liu, Yossi Shvartzvald, Seung‐Lee Kim, Chung‐Uk Lee, Dong-Joo Lee, Aparna Bhattacharya, Naoki Koshimoto, Sun‐Ju Chung, Cheongho Han, Grant Christie, T. Natusch, T. Sumi, Aikaterini Vandorou, A. Udalski, Youn Kil Jung, Qiyue Qian, Patryk Iwanek, Shota Miyazaki, Stela Ishitani Silva, Jiyuan Zhang, Renkun Kuang, I. A. Bond, P. Pietrukowicz, P. Mróz, K. Ulaczyk, Nicholas J. Rattenbury, Ryusei Hamada, In-Gu Shin, Greg Olmschenk, Yuki Hirao, Dan Maoz, Jennifer C. Yee, Y. Matsubara, P. J. Tristram, S. Kozłowski, Richard W. Pogge, Marcin Wrona, Y. Muraki, Mateusz J. Mróz, Kansuke Nunota, Dong-Jin Kim, Tutumi Nagai, Yunyi Tang, Berto Monard, Fumio Abe, Hongyu Li, Shunya Hamada, Andrew Gould, Ken Bando, Naoto Hamasak
article en

Abstract

Abstract We present the discovery and analysis of the sixth microlensing two-planet system, KMT-2022-BLG-1818Lb,c, detected by a follow-up program targeting high-magnification events. The second planet was identified from implausible physical parameters for the models with a single planet. Both planets are subject to the well-known “close/wide” degeneracy, although for the first planet, which has a super-Jovian mass ratio of q 2 ≃ 5 × 10 −3 in both solutions, the close topology, with a normalized separation of s ≃ 0.70, is clearly preferred by Δ χ 2 = 26. However, contrary to all previous two-planet microlensing systems, the mass ratio for the second planet, q 3 , is substantially (factor of ∼10) different for the Close and Wide topologies of the first planet. While this degeneracy is resolved in the present case due to high-cadence follow-up observations, the appearance of this new degeneracy indicates the need for caution in the analysis of future two-planet systems. A Bayesian analysis suggests that the host is likely a K dwarf star in the Galactic disk. The first planet is probably a super-Jupiter on a Jupiter-like orbit, while the second planet is a Saturn-class planet on either a Mercury-like or Saturn-like orbit.

The Astronomical JournalVol. 171(1)
Openalex Percentile: Top 72%
Stellar, planetary, and galactic studies
DOIOpen Access PDFOpenAlex
AI Navigator

Ask Laika to Summarize, Analyze, and Connect papers live on the map.

Summarize Papers & Methodologies

Extract key findings, datasets, and comparative methods across publications.

Benchmark Rankings & Visual Analytics

Rank top research institutions, authors, funders, topics, and journals by Field-Weighted Citation Impact (FWCI) and paper volume with instant charts.

Connect Distant Disciplines

Bridge topological clusters on the map to find hidden collaborative intersections.