Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published September 2019 | Submitted + Published
Journal Article Open

Spectroscopic Mass and Host-star Metallicity Measurements for Newly Discovered Microlensing Planet OGLE-2018-BLG-0740Lb

Abstract

We report the discovery of the microlensing planet OGLE-2018-BLG-0740Lb. The planet is detected with a very strong signal of Δχ^2 ~ 4630, but the interpretation of the signal suffers from two types of degeneracies. One type is caused by the previously known close/wide degeneracy, and the other is caused by an ambiguity between two solutions, in which one solution requires the incorporation of finite-source effects, while the other solution is consistent with a point-source interpretation. Although difficult to be firmly resolved based on only the photometric data, the degeneracy is resolved in strong favor of the point-source solution with the additional external information obtained from astrometric and spectroscopic observations. The small astrometric offset between the source and baseline object supports that the blend is the lens and this interpretation is further secured by the consistency of the spectroscopic distance estimate of the blend with the lensing parameters of the point-source solution. The estimated mass of the host is 1.0 ± 0.1 M⊙ and the mass of the planet is 4.5 ± 0.6 M_J (close solution) or 4.8 ± 0.6 M_J (wide solution) and the lens is located at a distance of 3.2 ± 0.5 kpc. The bright nature of the lens, with I ~ 17.1 (V ~ 18.2), combined with its dominance of the observed flux suggest that radial-velocity (RV) follow-up observations of the lens can be done using high-resolution spectrometers mounted on large telescopes, e.g., Very Large Telescope/ESPRESSO, and this can potentially not only measure the period and eccentricity of the planet but also probe for close-in planets. We estimate that the expected RV amplitude would be ~60sin I m s^(-1).

Additional Information

© 2019 The American Astronomical Society. Received 2019 April 30; revised 2019 June 26; accepted 2019 June 27; published 2019 August 8. 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. were supported by JPL grant 1500811. A.G. received support from the European Research Council under the European Union's Seventh Framework Programme (FP 7) ERC grant Agreement No. [321035]. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. S.D. acknowledges Project 11573003 supported by National Science Foundation of China (NSFC). The MOA project is supported by JSPS KAKENHI grant Nos. JSPS24253004, JSPS26247023, JSPS23340064, JSPS15H00781, JP16H06287, and JP17H02871. Y.M. acknowledges the support of the grant JP14002006. 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. The OGLE project has received funding from the National Science Centre, Poland, grant MAESTRO 2014/14/A/ST9/00121 to A.U. 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. We acknowledge the high-speed internet service (KREONET) provided by Korea Institute of Science and Technology Information (KISTI). We acknowledge the spectral fitting done by Yang Huang and Huawei Zhang.

Attached Files

Published - Han_2019_AJ_158_102.pdf

Submitted - 1905.00155.pdf

Files

1905.00155.pdf
Files (3.1 MB)
Name Size Download all
md5:bbdf5bedd47528325ca01c3257f27a8f
813.2 kB Preview Download
md5:b0733d4ee5d6500f5af88f78c3cc3840
2.3 MB Preview Download

Additional details

Created:
August 19, 2023
Modified:
October 18, 2023