MOA-2022-BLG-033Lb, KMT-2023-BLG-0119Lb, and KMT-2023-BLG-1896Lb: Three low mass-ratio microlensing planets detected through dip signals

¹ Department of Physics, Chungbuk National University, Cheongju 28644, Republic of Korea
² Institute of Natural and Mathematical Science, Massey University, Auckland 0745, New Zealand
³ Korea Astronomy and Space Science Institute, Daejon 34055, Republic of Korea
⁴ University of Canterbury, Department of Physics and Astronomy, Private Bag 4800, Christchurch 8020, New Zealand
⁵ Department of Astronomy, Ohio State University, 140 West 18th Ave., Columbus, OH 43210, USA
⁶ Max-Planck-Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
⁷ Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100, Israel
⁸ Center for Astrophysics | Harvard & Smithsonian 60 Garden St., Cambridge, MA 02138, USA
⁹ Department of Astronomy and Tsinghua Centre for Astrophysics, Tsinghua University, Beijing 100084, China
¹⁰ School of Space Research, Kyung Hee University, Yongin, Kyeonggi 17104, Republic of Korea
¹¹ Institute for Space-Earth Environmental Research, Nagoya University, Nagoya 464-8601, Japan
¹² Code 667, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
¹³ Department of Astronomy, University of Maryland, College Park, MD 20742, USA
¹⁴ Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
¹⁵ Instituto de Astrofísica de Canarias, Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
¹⁶ Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
¹⁷ Oak Ridge Associated Universities, Oak Ridge, TN 37830, USA
¹⁸ Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
¹⁹ Sorbonne Université, CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98 bis bd Arago, 75014 Paris, France
²⁰ Department of Physics, University of Auckland, Private Bag 92019 Auckland, New Zealand
²¹ University of Canterbury Mt. John Observatory, PO Box 56, Lake Tekapo 8770, New Zealand

^★ Corresponding authors; cheongho@astroph.chungbuk.ac.kr; younkil21@gmail.com

Received: 28 August 2024
Accepted: 3 January 2025

Abstract

Aims. We examined the anomalies in the light curves of the lensing events MOA-2022-BLG-033, KMT-2023-BLG-0119, and KMT- 2023-BLG-1896. These anomalies share similar traits: they occur near the peak of moderately to highly magnified events and display a distinct short-term dip feature.

Methods. We conducted detailed modeling of the light curves to uncover the nature of the anomalies. This modeling revealed that all signals originated from planetary companions to the primary lens. The planet-to-host mass ratios are very low: q ~ 7.5 × 10⁻⁵ for MOA-2022-BLG-033, q ~ 3.6 × 10⁻⁴ for KMT-2023-BLG-0119, and q ~ 6.9 × 10⁻⁵ for KMT-2023-BLG-1896. The anomalies occurred as the source passed through the negative deviation region behind the central caustic along the planet-host axis. The solutions are subject to a common inner-outer degeneracy, which results in varying estimations of the projected planet-host separation. For KMT-2023-BLG-1896, although the planetary scenario provides the best explanation for the anomaly, the binary companion scenario is possible.

Results. We estimated the physical parameters of the planetary systems through Bayesian analyses based on the lensing observables. While the event timescale was measured for all events, the angular Einstein radius was not measured for any. Additionally, the microlens parallax was measured for MOA-2022-BLG-033. The analysis identifies MOA-2022-BLG-033L as a planetary system with an ice giant with a mass of approximately 12 times that of Earth orbiting an early M dwarf star. The companion of KMT-2023-BLG-1896L is also an ice giant, with a mass of around 16 Earth masses, orbiting a mid-K-type main-sequence star. The companion of KMT-2023-BLG- 0119L, which has a mass around that of Saturn, orbits a mid-K-type dwarf star. The lens for MOA-2022-BLG-033 is highly likely to be located in the disk, whereas for the other events the probabilities of the lens being in the disk or the bulge are roughly equal.