J. Skowron, Y. Ryu, K. Hwang, A. Udalski, P. Mr'oz, S. Kozłowski, I. Soszy'nski, P. Pietrukowicz, M. Szyma'nski, R. Poleski, K. Ulaczyk, M. Pawlak, K. Rybicki, P. Iwanek, M. Albrow, S. Chung, A. Gould, C. Han, Y. Jung, I. Shin, Y. Shvartzvald, J. Yee, W. Zang, W. Zhu, S. Cha, D.-J. Kim, H.-W. Kim, S.-L. Kim, C.‐U. Lee, D.-J. Lee, Y. Lee, B.-G. Park, R. Pogge
{"title":"OGLE-2017-BLG-0373Lb:木星质量比行星暴露出一种新的偶然微透镜退化","authors":"J. Skowron, Y. Ryu, K. Hwang, A. Udalski, P. Mr'oz, S. Kozłowski, I. Soszy'nski, P. Pietrukowicz, M. Szyma'nski, R. Poleski, K. Ulaczyk, M. Pawlak, K. Rybicki, P. Iwanek, M. Albrow, S. Chung, A. Gould, C. Han, Y. Jung, I. Shin, Y. Shvartzvald, J. Yee, W. Zang, W. Zhu, S. Cha, D.-J. Kim, H.-W. Kim, S.-L. Kim, C.‐U. Lee, D.-J. Lee, Y. Lee, B.-G. Park, R. Pogge","doi":"10.32023/0001-5237/68.1.2","DOIUrl":null,"url":null,"abstract":"We report the discovery of microlensing planet OGLE-2017-BLG-0373Lb. We show that while the planet-host system has an unambiguous microlens topology, there are two geometries within this topology that fit the data equally well, which leads to a factor 2.5 difference in planet-host mass ratio, i.e., $q=1.5\\times 10^{-3}$ versus $q=0.6\\times 10^{-3}$. We show that this is an \"accidental degeneracy\" in the sense that it is due to a gap in the data. We dub it \"the caustic-chirality degeneracy\". We trace the mathematical origins of this degeneracy, which should enable similar degenerate solutions to be easily located in the future. A Bayesian estimate, based on a Galactic model, yields a host mass $M=0.25^{+0.30}_{-0.15} M_\\odot$ at a distance $D_L=5.9^{+1.3}_{-1.95}$ kpc. The lens-source relative proper motion is relatively fast, $\\mu=9$ mas/yr, which implies that the host mass and distance can be determined by high-resolution imaging after about 10 years. The same observations could in principle resolve the discrete degeneracy in $q$, but this will be more challenging.","PeriodicalId":44887,"journal":{"name":"Acta Astronomica","volume":null,"pages":null},"PeriodicalIF":2.0000,"publicationDate":"2018-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"7","resultStr":"{\"title\":\"OGLE-2017-BLG-0373Lb: A Jovian Mass-Ratio Planet Exposes A New Accidental Microlensing Degeneracy\",\"authors\":\"J. Skowron, Y. Ryu, K. Hwang, A. Udalski, P. Mr'oz, S. Kozłowski, I. Soszy'nski, P. Pietrukowicz, M. Szyma'nski, R. Poleski, K. Ulaczyk, M. Pawlak, K. Rybicki, P. Iwanek, M. Albrow, S. Chung, A. Gould, C. Han, Y. Jung, I. Shin, Y. Shvartzvald, J. Yee, W. Zang, W. Zhu, S. Cha, D.-J. Kim, H.-W. Kim, S.-L. Kim, C.‐U. Lee, D.-J. Lee, Y. Lee, B.-G. Park, R. Pogge\",\"doi\":\"10.32023/0001-5237/68.1.2\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"We report the discovery of microlensing planet OGLE-2017-BLG-0373Lb. We show that while the planet-host system has an unambiguous microlens topology, there are two geometries within this topology that fit the data equally well, which leads to a factor 2.5 difference in planet-host mass ratio, i.e., $q=1.5\\\\times 10^{-3}$ versus $q=0.6\\\\times 10^{-3}$. We show that this is an \\\"accidental degeneracy\\\" in the sense that it is due to a gap in the data. We dub it \\\"the caustic-chirality degeneracy\\\". We trace the mathematical origins of this degeneracy, which should enable similar degenerate solutions to be easily located in the future. A Bayesian estimate, based on a Galactic model, yields a host mass $M=0.25^{+0.30}_{-0.15} M_\\\\odot$ at a distance $D_L=5.9^{+1.3}_{-1.95}$ kpc. The lens-source relative proper motion is relatively fast, $\\\\mu=9$ mas/yr, which implies that the host mass and distance can be determined by high-resolution imaging after about 10 years. The same observations could in principle resolve the discrete degeneracy in $q$, but this will be more challenging.\",\"PeriodicalId\":44887,\"journal\":{\"name\":\"Acta Astronomica\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.0000,\"publicationDate\":\"2018-02-27\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"7\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Acta Astronomica\",\"FirstCategoryId\":\"101\",\"ListUrlMain\":\"https://doi.org/10.32023/0001-5237/68.1.2\",\"RegionNum\":4,\"RegionCategory\":\"物理与天体物理\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"ASTRONOMY & ASTROPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Acta Astronomica","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.32023/0001-5237/68.1.2","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
OGLE-2017-BLG-0373Lb: A Jovian Mass-Ratio Planet Exposes A New Accidental Microlensing Degeneracy
We report the discovery of microlensing planet OGLE-2017-BLG-0373Lb. We show that while the planet-host system has an unambiguous microlens topology, there are two geometries within this topology that fit the data equally well, which leads to a factor 2.5 difference in planet-host mass ratio, i.e., $q=1.5\times 10^{-3}$ versus $q=0.6\times 10^{-3}$. We show that this is an "accidental degeneracy" in the sense that it is due to a gap in the data. We dub it "the caustic-chirality degeneracy". We trace the mathematical origins of this degeneracy, which should enable similar degenerate solutions to be easily located in the future. A Bayesian estimate, based on a Galactic model, yields a host mass $M=0.25^{+0.30}_{-0.15} M_\odot$ at a distance $D_L=5.9^{+1.3}_{-1.95}$ kpc. The lens-source relative proper motion is relatively fast, $\mu=9$ mas/yr, which implies that the host mass and distance can be determined by high-resolution imaging after about 10 years. The same observations could in principle resolve the discrete degeneracy in $q$, but this will be more challenging.