OGLE-2017-BLG-0373Lb: A Jovian Mass-Ratio Planet Exposes A New Accidental Microlensing Degeneracy

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dc.contributor.authorSkowron J
dc.contributor.authorRyu Y-H
dc.contributor.authorHwang K-H
dc.contributor.authorUdalski A
dc.contributor.authorMróz P
dc.contributor.authorKozłowski S
dc.contributor.authorSoszyński I
dc.contributor.authorPietrukowicz P
dc.contributor.authorSzymański MK
dc.contributor.authorPoleski R
dc.contributor.authorUlaczyk K
dc.contributor.authorPawlak M
dc.contributor.authorRybicki K
dc.contributor.authorIwanek P
dc.contributor.authorAlbrow MD
dc.contributor.authorChung S-J
dc.contributor.authorGould A
dc.contributor.authorHan C
dc.contributor.authorJung YK
dc.contributor.authorShin I-G
dc.contributor.authorShvartzvald Y
dc.contributor.authorYee JC
dc.contributor.authorZang W
dc.contributor.authorZhu RW
dc.contributor.authorCha S-M
dc.contributor.authorKim D-J
dc.contributor.authorKim H-W
dc.contributor.authorKim S-L
dc.contributor.authorLee C-U
dc.contributor.authorLee D-J
dc.contributor.authorLee Y
dc.contributor.authorPark B-G
dc.contributor.authorPogge RW
dc.date.accessioned2018-04-23T02:15:56Z
dc.date.available2018-04-23T02:15:56Z
dc.date.issued2018en
dc.date.updated2018-04-05T23:37:40Z
dc.description.abstractWe 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.en
dc.identifier.urihttp://hdl.handle.net/10092/15188
dc.language.isoen
dc.subjectastro-ph.EPen
dc.subjectgravitational lensing: microen
dc.subject.anzsrcField of Research::02 - Physical Sciences::0201 - Astronomical and Space Sciences::020108 - Planetary Science (excl. Extraterrestrial Geology)en
dc.subject.anzsrcField of Research::02 - Physical Sciences::0201 - Astronomical and Space Sciences::020102 - Astronomical and Space Instrumentationen
dc.titleOGLE-2017-BLG-0373Lb: A Jovian Mass-Ratio Planet Exposes A New Accidental Microlensing Degeneracyen
dc.typeJournal Articleen
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