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Revisiting MOA 2013-BLG-220L: a solar-type star with a cold super-Jupiter companion

Citation

Vandorou, A and Bennett, DP and Beaulieu, J-P and Alard, C and Blackman, JW and Cole, AA and Bhattacharya, A and Bond, IA and Koshimoto, N and Marquette, J-B, Revisiting MOA 2013-BLG-220L: a solar-type star with a cold super-Jupiter companion, Astronomical Journal, 160, (3) Article 121. ISSN 0004-6256 (2020) [Refereed Article]

Copyright Statement

© 2020. The American Astronomical Society

DOI: doi:10.3847/1538-3881/aba2d3

Abstract

We present the analysis of high-resolution images of MOA-2013-BLG-220, taken with the Keck adaptive optics system six years after the initial observation, identifying the lens as a solar-type star hosting a super-Jupiter-mass planet. The masses of planets and host stars discovered by microlensing are often not determined from light-curve data, while the star–planet mass ratio and projected separation in units of Einstein ring radius are well measured. High-resolution follow-up observations after the lensing event is complete can resolve the source and lens. This allows direct measurements of flux, and the amplitude and direction of proper motion, giving strong constraints on the system parameters. Due to the high relative proper motion, μrel,Geo = 12.62 ± 0.11 mas yr-1, the source and lens were resolved in 2019, with a separation of 77.1 ± 0.5 mas. Thus, we constrain the lens flux to KKeck,lens = 17.92 ± 0.02. By combining constraints from the model and Keck flux, we find the lens mass to be ML = 0.88 ± 0.05 M at DL = 6.72 ± 0.59 kpc. With a mass ratio of q = (3.00 ± 0.03) x 10-3 the planet’s mass is determined to be MP = 2.74 ± 0.17 MJ at a separation of r = 3.03 ± 0.27 au. The lens mass is much higher than the prediction made by Bayesian analysis that assumes all stars have an equal probability to host a planet of the measured mass ratio, and suggests that planets with mass ratios of a few times 10-3 are more common orbiting massive stars. This demonstrates the importance of high-resolution follow-up observations for testing theories like these.

Item Details

Item Type:Refereed Article
Keywords:exoplanets; gravitational microlensing; proper motions
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Stellar astronomy and planetary systems
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Vandorou, A ( Aikaterini Vandorou)
UTAS Author:Beaulieu, J-P (Dr Jean-Philippe Beaulieu)
UTAS Author:Blackman, JW (Mr Joshua Blackman)
UTAS Author:Cole, AA (Associate Professor Andrew Cole)
ID Code:141064
Year Published:2020
Funding Support:Australian Research Council (DP200101909)
Web of Science® Times Cited:11
Deposited By:Physics
Deposited On:2020-09-22
Last Modified:2020-10-07
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