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A Planetary Microlensing Event with an Unusually Red Source Star: MOA-2011-BLG-291

Bennett, David P. and Shvartzvald, Yossi (2018) A Planetary Microlensing Event with an Unusually Red Source Star: MOA-2011-BLG-291. Astronomical Journal, 156 (3). Art. No. 113. ISSN 1538-3881. doi:10.3847/1538-3881/aad59c.

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We present the analysis of the planetary microlensing event MOA-2011-BLG-291, which has a mass ratio of q = (3.8 ± 0.7) × 10−4 and a source star that is redder (or brighter) than the bulge main sequence. This event is located at a low Galactic latitude in the survey area that is currently planned for NASA's Wide Field Infrared Survey Telescope (WFIRST) exoplanet microlensing survey. This unusual color for a microlensed source star implies that we cannot assume that the source star is in the Galactic bulge. The favored interpretation is that the source star is a lower main-sequence star at a distance of D_S = 4.9 ± 1.3 kpc in the Galactic disk. However, the source could also be a turn-off star on the far side of the bulge or a subgiant in the far side of the Galactic disk if it experiences significantly more reddening than the bulge red clump stars. However, these possibilities have only a small effect on our mass estimates for the host star and planet. We find host star and planet masses of M_(host) = 0.15^(+0.27)_(-0.10) M⊙ and m_p = 18^(+34)_(-12) M⊕ from a Bayesian analysis with a standard Galactic model, under the assumption that the planet hosting probability does not depend on the host mass or distance. However, if we attempt to measure the host and planet masses with host star brightness measurements from high angular resolution follow-up imaging, the implied masses will be sensitive to the host star distance. The WFIRST exoplanet microlensing survey is expected to use this method to determine the masses for many of the planetary systems that it discovers, so this issue has important design implications for the WFIRST exoplanet microlensing survey.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Bennett, David P.0000-0001-8043-8413
Shvartzvald, Yossi0000-0003-1525-5041
Additional Information:© 2018 The American Astronomical Society. Received 2018 June 7; revised 2018 July 18; accepted 2018 July 22; published 2018 August 23. D.P.B., A.B., and C.R. were supported by NASA through grant NASA-80NSSC18K0274. The MOA project is supported in Japan by JSPS KAKENHI grant Numbers JP17H02871, JSPS24253004, JSPS26247023, JSPS23340064, JSPS15H00781, and JP16H06287. 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. The OGLE Team thanks Profs. Marcin Kubiak and Grzegorz Pietrzyński for their contribution to the OGLE photometric data. The OGLE project has received funding from the National Science Centre, Poland, grant MAESTRO 2014/14/A/ST9/00121 to AU. The Wise group was supported by the I-CORE programme of the Planning and Budgeting Committee and the Israel Science Foundation, Grant 1829/12. D.M. and A.G. acknowledge support by the US-Israel Binational Science Foundation. Work by C.H. was supported by the grant (2017R1A4A1015178) of the National Research Foundation of Korea.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Japan Society for the Promotion of Science (JSPS)JP17H02871
Japan Society for the Promotion of Science (JSPS)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
NASA Postdoctoral ProgramUNSPECIFIED
Royal Society of New ZealandUNSPECIFIED
National Science Centre (Poland)MAESTRO 2014/14/A/ST9/00121
I-CORE Program of the Planning and Budgeting CommitteeUNSPECIFIED
Israel Science Foundation1829/12
Binational Science Foundation (USA-Israel)UNSPECIFIED
National Research Foundation of Korea2017R1A4A1015178
Subject Keywords:gravitational lensing: micro – planetary systems
Issue or Number:3
Record Number:CaltechAUTHORS:20180822-154729671
Persistent URL:
Official Citation:David P. Bennett et al 2018 AJ 156 113
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89065
Deposited By: Tony Diaz
Deposited On:22 Aug 2018 23:01
Last Modified:16 Nov 2021 00:31

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