MOA-2020-BLG-208Lb: Cool Sub-Saturn Planet Within Predicted Desert

Abstract

We analyze the MOA-2020-BLG-208 gravitational microlensing event and present the discovery and characterization of a new planet, MOA-2020-BLG-208Lb, with an estimated sub-Saturn mass. With a mass ratio $q=3.17_{-0.26}^{+0.28}\times 10^{-4}$ and a separation $s=1.3807_{-0.0018}^{+0.0018}$, the planet lies near the peak of the mass-ratio function derived by the MOA collaboration (Suzuki et al. 2016), near the edge of expected sample sensitivity. For these estimates we provide results using two mass law priors: one assuming that all stars have an equal planet-hosting probability, and the other assuming that planets are more likely to orbit around more massive stars. In the first scenario, we estimate that the lens system is likely to be a planet of mass $m_{\mathrm{planet}}=46_{-24}^{+42}{M}_{\oplus }$ and a host star of mass $M_{\mathrm{host}}=0.43_{-0.23}^{+0.39}{M}_{\odot }$, located at a distance $D_L=7.49_{-1.13}^{+0.99}\mathrm{kpc}$. For the second scenario, we estimate $m_{\mathrm{planet}}=69_{-34}^{+37}{M}_{\oplus }$, $M_{\mathrm{host}}=0.66_{-0.32}^{+0.35}{M}_{\odot }$, and $D_L=7.81_{-0.93}^{+0.93}\mathrm{kpc}$. As a cool sub-Saturn-mass planet, this planet adds to a growing collection of evidence for revised planetary formation models and qualifies for inclusion in the extended MOA-II exoplanet microlensing sample.

References in corpus (9)

• One or more bound planets per Milky Way star from microlensing observations
• The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics From 10-100 AU
• A New Planet Around an M Dwarf: Revealing a Correlation Between Exoplanets and Stellar Mass
• The Exoplanet Mass-Ratio Function from the MOA-II Survey: Discovery of a Break and Likely Peak at a Neptune Mass
• Microlensing Results Challenge the Core Accretion Runaway Growth Scenario for Gas Giants
• A Parametric Galactic Model toward the Galactic Bulge Based on Gaia and Microlensing Data
• MOA-2007-BLG-400 A Super-Jupiter Mass Planet Orbiting a Galactic BulgeK-dwarf Revealed by Keck Adaptive Optics Imaging
• Systematic KMTNet Planetary Anomaly Search, Paper III: One Wide-Orbit Planet And Two Stellar Binaries
• No Large Dependence of Planet Frequency on Galactocentric Distance

Cited by in corpus (1)

• Gaia21blx: Complete resolution of a binary microlensing event in the Galactic disk