MOA-2016-BLG-319Lb: Microlensing Planet Subject to Rare Minor-image Perturbation Degeneracy in Determining Planet Parameters
Abstract
We present the analysis of the planetary microlensing event MOA-2016-BLG-319. The event light curve is characterized by a brief (~3 days) anomaly near the peak produced by minor-image perturbations. From modeling, we find two distinct solutions that describe the observed light curve almost equally as well. From the investigation of the lens-system configurations, we find that the confusion in the lensing solution is caused by the degeneracy between the two solutions resulting from the source passages on different sides of the planetary caustic. These degeneracies can be severe for major-image perturbations, but it is known that they are considerably less severe for minor-image perturbations. From the comparison of the lens-system configuration with those of two previously discovered planetary events, for which similar degeneracies were reported, we find that the degeneracies are caused by the special source trajectories that passed the star–planet axes at approximately right angles. By conducting a Bayesian analysis, it is estimated that the lens is a planetary system in which a giant planet with a mass M_p = 0.62^(+1.16)_(-0.33) M_J (0.65^(+1.21)_(-0.35) M_J) is orbiting a low-mass M-dwarf host with a mass M_h = 0.15^(+0.28)_(-0.08) M⊙ . Here the planet masses in and out of the parentheses represent the masses for the individual degenerate solutions. The projected host-planet separations are a⊥ ~ 0.95 and ~1.05 au for the two solutions. The identified degeneracy indicates the need to check similar degeneracies in future analyses of planetary lensing events with minor-image perturbations.
Additional Information
© 2018 The American Astronomical Society. Received 2018 August 19; revised 2018 September 17; accepted 2018 September 20; published 2018 October 26. Work by C.H. was supported by the grant (2017R1A4A1015178) of National Research Foundation of Korea. Work by A.G. was supported by US NSF grant AST-1516842. Work by I.G.S. and A.G. was supported by JPL grant 1500811. This research has made use of the KMTNet system operated by the Korea Astronomy and Space Science Institute (KASI) and the data were obtained at three host sites of CTIO in Chile, SAAO in South Africa, and SSO in Australia. The MOA project was supported by JSPS KAKENHI grant No. JSPS24253004, JSPS26247023, JSPS23340064, JSPS15H00781, and JP16H06287. D.P.B., A.B., and C.R. were supported by NASA through grant NASA-80NSSC18K0274. The work by C.R. was supported by an appointment to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by USRA through a contract with NASA. N.J.R. is a Royal Society of New Zealand Rutherford Discovery Fellow. We acknowledge the high-speed internet service (KREONET) provided by Korea Institute of Science and Technology Information (KISTI).Attached Files
Published - Han_2018_AJ_156_226.pdf
Submitted - 1809.07898.pdf
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Additional details
- Eprint ID
- 90428
- Resolver ID
- CaltechAUTHORS:20181026-101110631
- 2017R1A4A1015178
- National Research Foundation of Korea
- AST-1516842
- NSF
- 1500811
- JPL
- JSPS24253004
- Japan Society for the Promotion of Science (JSPS)
- JSPS26247023
- Japan Society for the Promotion of Science (JSPS)
- JSPS23340064
- Japan Society for the Promotion of Science (JSPS)
- JSPS15H00781
- Japan Society for the Promotion of Science (JSPS)
- JP16H06287
- Japan Society for the Promotion of Science (JSPS)
- 80NSSC18K0274
- NASA
- NASA Postdoctoral Program
- Royal Society of New Zealand
- Created
-
2018-10-26Created from EPrint's datestamp field
- Updated
-
2021-11-16Created from EPrint's last_modified field
- Caltech groups
- Infrared Processing and Analysis Center (IPAC)