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MOA-2009-BLG-319Lb: A sub-saturn planet inside the predicted mass desert


Terry, SK and Bhattacharya, A and Bennett, DP and Beaulieu, J-P and Koshimoto, N and Blackman, JW and Bond, IA and Cole, AA and Henderson, CB and Lu, JR and Marquette, JB and Ranc, C and Vandorou, A, MOA-2009-BLG-319Lb: A sub-saturn planet inside the predicted mass desert, Astronomical Journal, 161, (2) Article 54. ISSN 0004-6256 (2021) [Refereed Article]

Copyright Statement

Copyright 2021. The American Astronomical Society

DOI: doi:10.3847/1538-3881/abcc60


We present an adaptive optics (AO) analysis of images from the Keck II telescope NIRC2 instrument of the planetary microlensing event MOA-2009-BLG-319. The ~10 yr baseline between the event and the Keck observations allows the planetary host star to be detected at a separation of 66.51.7 mas from the source star, consistent with the light-curve model prediction. The combination of the host star brightness and light-curve parameters yields host star and planet masses of Mhost=0.5240.048M and mp=67.36.2M at a distance of DL=7.10.7 kpc. The star−planet projected separation is 2.030.21 au. The planet-to-star mass ratio of this system, q=(3.8570.029)נ10−4, places it in the predicted "planet desert" at 10−4<q<4נ10−4 according to the runaway gas accretion scenario of the core accretion theory. Seven of the 30 planets in the Suzuki et al. sample fall in this mass ratio range, and this is the third with a measured host mass. All three of these host stars have masses of 0.5≤Mhost/M≤0.7, which implies that this predicted mass ratio gap is filled with planets that have host stars within a factor of two of 1M. This suggests that runaway gas accretion does not play a major role in determining giant planet masses for stars somewhat less massive than the Sun. Our analysis has been accomplished with a modified DAOPHOT code that has been designed to measure the brightness and positions of closely blended stars. This will aid in the development of the primary method that the Nancy Grace Roman Space Telescope mission will use to determine the masses of microlens planets and their hosts.

Item Details

Item Type:Refereed Article
Keywords:gravitational microlensing, exoplanets, red dwarf stars
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:Beaulieu, J-P (Dr Jean-Philippe Beaulieu)
UTAS Author:Blackman, JW (Mr Joshua Blackman)
UTAS Author:Cole, AA (Professor Andrew Cole)
UTAS Author:Vandorou, A ( Aikaterini Vandorou)
ID Code:142325
Year Published:2021
Funding Support:Australian Research Council (DP200101909)
Web of Science® Times Cited:9
Deposited By:Physics
Deposited On:2021-01-08
Last Modified:2021-04-09

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