The Star Blended with the MOA-2008-BLG-310 Source Is Not the Exoplanet Host Star

Abstract

High resolution Hubble Space Telescope (HST) image analysis of the MOA-2008-BLG-310 microlens system indicates that the excess flux at the location of the source found in the discovery paper cannot primarily be due to the lens star because it does not match the lens-source relative proper motion, ${\mu }_{\mathrm{rel}}$, predicted by the microlens models. This excess flux is most likely to be due to an unrelated star that happens to be located in close proximity to the source star. Two epochs of HST observations indicate proper motion for this blend star that is typical of a random bulge star, but is not consistent with a companion to the source or lens stars if the flux is dominated by only one star, aside from the lens. We consider models in which the excess flux is due to a combination of an unrelated star and the lens star, and this yields 95\% confidence level upper limit on the lens star brightness of $I_L>22.44$ and $V_L>23.62$. A Bayesian analysis using a standard Galactic model and these magnitude limits yields a host star mass $M_h=0.21_{-0.09}^{+0.21}{M}_{\odot }$, a planet mass of $m_p=23.4_{-9.9}^{+23.9}{M}_{\oplus }$ at a projected separation of $a_{\perp }=1.12_{-0.17}^{+0.16},$AU. This result illustrates excess flux in a high resolution image of a microlens-source system need not be due to the lens. It is important to check that the lens-source relative proper motion is consistent with the microlensing prediction. The high resolution image analysis techniques developed in this paper can be used to verify the WFIRST exoplanet microlensing survey mass measurements.

arXiv commentSubmitted to AJ on March 18, 2017

References in corpus (57)

• Stellar Multiplicity
• The WASP Project and the SuperWASP Cameras
• Wide-Field InfrarRed Survey Telescope-Astrophysics Focused Telescope Assets WFIRST-AFTA 2015 Report
• Catalog of Nearby Exoplanets
• Drizzle: A Method for the Linear Reconstruction of Undersampled Images
• Discovery of a Cool Planet of 5.5 Earth Masses Through Gravitational Microlensing
• Reddening and Extinction Toward the Galactic Bulge from OGLE-III: The Inner Milky Way's Rv ~ 2.5 Extinction Curve
• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Parameter Estimation Methodology
• Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. V. Evidence for a wide age distribution and a complex MDF
• The angular size of dwarf stars and subgiants - Surface brightness relations calibrated by interferometry
• VVV DR1: The First Data Release of the Milky Way Bulge and Southern Plane from the Near-Infrared ESO Public Survey VISTA Variables in the Via Lactea
• The Use of High Magnification Microlensing Events in Discovering Extra-solar Planets
• Discovery of a Jupiter/Saturn Analog with Gravitational Microlensing
• Terrestrial Planet Occurrence Rates for the Kepler GK Dwarf Sample
• Toward High-Precision Astrometry with WFPC2. I. Deriving an Accurate PSF
• Microlens OGLE-2005-BLG-169 Implies Cool Neptune-Like Planets are Common
• Detecting Earth-Mass Planets with Gravitational Microlensing
• A Low-Mass Planet with a Possible Sub-Stellar-Mass Host in Microlensing Event MOA-2007-BLG-192
• The Exoplanet Mass-Ratio Function from the MOA-II Survey: Discovery of a Break and Likely Peak at a Neptune Mass
• An Empirical Pixel-Based Correction for Imperfect CTE. I. HST's Advanced Camera for Surveys
• On the Location of the Snow Line in a Protoplanetary Disk
• A Cold Neptune-Mass Planet OGLE-2007-BLG-368Lb: Cold Neptunes Are Common
• Simulation of a Space-Based Microlensing Survey for Terrestrial Extra-Solar Planets
• OGLE-2005-BLG-071Lb, the Most Massive M-Dwarf Planetary Companion?
• A Sub-Earth-Mass Moon Orbiting a Gas Giant Primary or a High Velocity Planetary System in the Galactic Bulge
• Masses and Orbital Constraints for the OGLE-2006-BLG-109Lb,c Jupiter/Saturn Analog Planetary System
• Microlensing Event MOA-2007-BLG-400: Exhuming the Buried Signature of a Cool, Jovian-Mass Planet
• Stellar Diameters and Temperatures IV. Predicting Stellar Angular Diameters
• Identification of the OGLE-2003-BLG-235/MOA-2003-BLG-53 Planetary Host Star
• The Progenitors of the Compact Early-Type Galaxies at High-Redshift
• Characterization of Gravitational Microlensing Planetary Host Stars
• Sub-Saturn Planet MOA-2008-BLG-310Lb: Likely To Be In The Galactic Bulge
• Discovery and Mass Measurements of a Cold, 10-Earth Mass Planet and Its Host Star
• The First Circumbinary Planet Found by Microlensing: OGLE-2007-BLG-349L(AB)c
• An Efficient Method for Modeling High Magnification Planetary Microlensing Events
• Triple Microlens OGLE-2008-BLG-092L: Binary Stellar System with a Circumprimary Uranus-type Planet
• The SAMI Galaxy Survey: Towards a unified dynamical scaling relation for galaxies of all types
• MOA-2011-BLG-293Lb: First Microlensing Planet possibly in the Habitable Zone
• OGLE-2012-BLG-0563Lb: a Saturn-mass Planet around an M Dwarf with the Mass Constrained by Subaru AO imaging
• Planet formation around low mass stars: the moving snow line and super-Earths
• Macho Parallaxes From A Single Satellite
• Gas dynamics in the Milky Way: a low pattern speed model
• A frozen super-Earth orbiting a star at the bottom of the Main Sequence
• Revisiting the microlensing event OGLE 2012-BLG-0026: A solar mass star with two cold giant planets
• The First Neptune Analog or Super-Earth with Neptune-like Orbit: MOA-2013-BLG-605Lb
• Mapping stellar kinematics across the Galactic bar: HST measurements of proper motions in 35 fields
• A sub-Saturn Mass Planet, MOA-2009-BLG-319Lb
• OGLE-2012-BLG-0950Lb: The First Planet Mass Measurement from Only Microlens Parallax and Lens Flux
• Near-Infrared Spectroscopy of the Y0 WISEP J173835.52+273258.9 and the Y1 WISE J035000.32-565830.2: the Importance of Non-Equilibrium Chemistry
• Microlens Parallaxes with SIRTF
• The Varying Light Curve and Timings of the Ultra-short Period Contact Binary KIC 9532219
• Evidence for a planetary mass third body orbiting the binary star KIC 5095269
• OGLE-2008-BLG-355Lb: A Massive Planet around A Late type Star
• Microlensing by Kuiper, Oort, and Free-Floating Planets
• MOA 2011-BLG-028Lb: a Neptune-mass Microlensing Planet in the Galactic Bulge
• Discovery of a Gas giant Planet in Microlensing Event OGLE-2014-BLG-1760
• OGLE-2012-BLG-0724Lb: A Saturn-mass Planet around an M-dwarf

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• A Planetary Microlensing Event with an Unusually Red Source Star: MOA-2011-BLG-291
• UKIRT-2017-BLG-001Lb: A giant planet detected through the dust
• No Large Dependence of Planet Frequency on Galactocentric Distance
• A Likely Detection of a Two-Planet System in a Low Magnification Microlensing Event
• Bayesian Approach for Determining Microlens System Properties with High-Angular-Resolution Follow-up Imaging
• OGLE-2017-BLG-0406: $Spitzer$ Microlens Parallax Reveals Saturn-mass Planet orbiting M-dwarf Host in the Inner Galactic Disk
• OGLE-2013-BLG-1761Lb: A Massive Planet Around an M/K Dwarf
• OGLE-2015-BLG-1670Lb: A Cold Neptune beyond the Snow Line in the Provisional WFIRST Microlensing Survey Field
• MOA-bin-29b : A Microlensing Gas Giant Planet Orbiting a Low-mass Host Star
• KMT-2019-BLG-0371 and the Limits of Bayesian Analysis
• OGLE-2013-BLG-0911Lb: A Secondary on the Brown-Dwarf Planet Boundary around an M-dwarf
• A Wide Orbit Exoplanet OGLE-2012-BLG-0838Lb
• OGLE-2015-BLG-1649Lb: A gas giant planet around a low-mass dwarf
• OGLE-2016-BLG-0156: Microlensing Event With Pronounced Microlens-Parallax Effects Yielding Precise Lens Mass Measurement
• Casting Light on Degeneracies: A Comprehensive Study of Lightcurve Variations in Microlensing Events OGLE-2017-BLG-0103 and OGLE-2017-BLG-0192