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arXiv · 2404.13031

OGLE-2015-BLG-0845L: A low-mass M dwarf from the microlensing parallax and xallarap effects

Zhecheng Hu·Wei Zhu·Andrew Gould·Andrzej Udalski·Takahiro Sumi·Ping Chen·Sebastiano Calchi Novati·Jennifer C. Yee·Charles A. Beichman·Geoffery Bryden·Sean Carey·Michael Fausnaugh·B. Scott Gaudi·Calen B. Henderson·Yossi Shvartzvald·Benjamin Wibking·Przemek Mróz·Jan Skowron·Radosław Poleski·Michał K. Szymański·Igor Soszyński·Paweł Pietrukowicz·Szymon Kozłowski·Krzysztof Ulaczyk·Krzysztof A. Rybicki·Patryk Iwanek·Marcin Wrona·Mariusz Gromadzki·Fumio Abe·Richard Barry·David P. Bennett·Aparna Bhattacharya·Ian A. Bond·Hirosane Fujii·Akihiko Fukui·Ryusei Hamada·Yuki Hirao·Stela Ishitani Silva·Yoshitaka Itow·Rintaro Kirikawa·Naoki Koshimoto·Yutaka Matsubara·Shota Miyazaki·Yasushi Muraki·Greg Olmschenk·Clément Ranc·Nicholas J. Rattenbury·Yuki Satoh·Daisuke Suzuki·Mio Tomoyoshi·Paul. J. Tristram·Aikaterini Vandorou·Hibiki Yama·Kansuke Yamashita
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Abstract

We present the analysis of the microlensing event OGLE-2015-BLG-0845, which was affected by both the microlensing parallax and xallarap effects. The former was detected via the simultaneous observations from the ground and Spitzer, and the latter was caused by the orbital motion of the source star in a relatively close binary. The combination of these two effects led to a mass measurement of the lens object, revealing a low-mass ($0.14 \pm 0.05 M_{\odot}$) M-dwarf at the bulge distance ($7.6 \pm 1.0$ kpc). The source binary consists of a late F-type subgiant and a K-type dwarf of $\sim1.2 M_{\odot}$ and $\sim 0.9 M_{\odot}$, respectively, and the orbital period is $70 \pm 10$ days. OGLE-2015-BLG-0845 is the first single-lens event in which the lens mass is measured via the binarity of the source. Given the abundance of binary systems as potential microlensing sources, the xallarap effect may not be a rare phenomenon. Our work thus highlights the application of the xallarap effect in the mass determination of microlenses, and the same method can be used to identify isolated dark lenses.

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Zhecheng Hu, Wei Zhu, Andrew Gould, Andrzej Udalski, Takahiro Sumi, Ping Chen, Sebastiano Calchi Novati, Jennifer C. Yee, Charles A. Beichman, Geoffery Bryden, Sean Carey, Michael Fausnaugh, B. Scott Gaudi, Calen B. Henderson, Yossi Shvartzvald, Benjamin Wibking, Przemek Mróz, Jan Skowron, Radosław Poleski, Michał K. Szymański, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Mariusz Gromadzki, Fumio Abe, Richard Barry, David P. Bennett, Aparna Bhattacharya, Ian A. Bond, Hirosane Fujii, Akihiko Fukui, Ryusei Hamada, Yuki Hirao, Stela Ishitani Silva, Yoshitaka Itow, Rintaro Kirikawa, Naoki Koshimoto, Yutaka Matsubara, Shota Miyazaki, Yasushi Muraki, Greg Olmschenk, Clément Ranc, Nicholas J. Rattenbury, Yuki Satoh, Daisuke Suzuki, Mio Tomoyoshi, Paul. J. Tristram, Aikaterini Vandorou, Hibiki Yama, Kansuke Yamashita. 2024-04-19. OGLE-2015-BLG-0845L: A low-mass M dwarf from the microlensing parallax and xallarap effects. https://arxiv.org/abs/2404.13031

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