OGLE-2019-BLG-0825: constraints on the source system and effect on binary-lens parameters arising from a five day xallarap effect in a candidate planetary microlensing event

Yuki K. Satoh*, Naoki Koshimoto, David P. Bennett, Takahiro Sumi, Nicholas J. Rattenbury, Daisuke Suzuki, Shota Miyazaki, Ian A. Bond, Andrzej Udalski, Andrew Gould, Valerio Bozza, Martin Dominik, Yuki Hirao, Iona Kondo, Rintaro Kirikawa, Ryusei Hamada, Fumio Abe, Richard Barry, Aparna Bhattacharya, Hirosane FujiiAkihiko Fukui, Katsuki Fujita, Tomoya Ikeno, Stela Ishitani Silva, Yoshitaka Itow, Yutaka Matsubara, Sho Matsumoto, Yasushi Muraki, Kosuke Niwa, Arisa Okamura, Greg Olmschenk, Clément Ranc, Taiga Toda, Mio Tomoyoshi, Paul J. Tristram, Aikaterini Vandorou, Hibiki Yama, Kansuke Yamashita, Przemek Mróz, Radosław Poleski, Jan Skowron, Michał K. Szymański, Radek Poleski, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Mariusz Gromadzki, Michael D. Albrow, Sun-Ju Chung, Cheongho Han, Kyu-Ha Hwang, Doeon Kim, Youn Kil Jung, Hyoun Woo Kim, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Hongjing Yang, Jennifer C. Yee, Weicheng Zang, Sang-Mok Cha, Dong-Jin Kim, Seung-Lee Kim, Chung-Uk Lee, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Uffe G. Jørgensen, Penélope Longa-Peña, Sedighe Sajadian, Jesper Skottfelt, Colin Snodgrass, Jeremy Tregloan-Reed, Nanna Bach-Møller, Martin Burgdorf, Giuseppe D'Ago, Lauri Haikala, James Hitchcock, Markus Hundertmark, Elahe Khalouei, Nuno Peixinho, Sohrab Rahvar, John Southworth, Petros Spyratos

*Corresponding author for this work

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Abstract

We present an analysis of microlensing event OGLE-2019-BLG-0825. This event was identified as a planetary candidate by preliminary modeling. We find that significant residuals from the best-fit static binary-lens model exist and a xallarap effect can fit the residuals very well and significantly improves χ2 values. On the other hand, by including the xallarap effect in our models, we find that binary-lens parameters like mass-ratio, q, and separation, s, cannot be constrained well. However, we also find that the parameters for the source system like the orbital period and semi major axis are consistent between all the models we analyzed. We therefore constrain the properties of the source system better than the properties of the lens system. The source system comprises a G-type main-sequence star orbited by a brown dwarf with a period of P ∼ 5 days. This analysis is the first to demonstrate that the xallarap effect does affect binary-lens parameters in planetary events. It would not be common for the presence or absence of the xallarap effect to affect lens parameters in events with long orbital periods of the source system or events with transits to caustics, but in other cases, such as this event, the xallarap effect can affect binary-lens parameters.
Original languageEnglish
Article number116
Number of pages15
JournalAstronomical Journal
Volume166
Issue number3
Early online date18 Aug 2023
DOIs
Publication statusPublished - 1 Sept 2023

Keywords

  • Gravitational lensing: micro
  • Brown dwarfs
  • Xallarap effect

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