The First Dynamical Mass Measurement in the HR 8799 System

Abstract

HR 8799 hosts four directly imaged giant planets, but none has a mass measured from first principles. We present the first dynamical mass measurement in this planetary system, finding that the innermost planet HR~8799~e has a mass of $9.6_{-1.8}^{+1.9}{M}_{\mathrm{Jup}}$. This mass results from combining the well-characterized orbits of all four planets with a new astrometric acceleration detection (5$\sigma$) from the Gaia EDR3 version of the Hipparcos-Gaia Catalog of Accelerations. We find with 95\% confidence that HR~8799~e is below $13M_{\mathrm{Jup}}$, the deuterium-fusing mass limit. We derive a hot-start cooling age of $42_{-16}^{+24}$\,Myr for HR~8799~e that agrees well with its hypothesized membership in the Columba association but is also consistent with an alternative suggested membership in the $\beta$~Pictoris moving group. We exclude the presence of any additional $\gtrsim$5-$M_{\mathrm{Jup}}$ planets interior to HR~8799~e with semi-major axes between $\approx$3-16\,au. We provide proper motion anomalies and a matrix equation to solve for the mass of any of the planets of HR~8799 using only mass ratios between the planets.

arXiv commentAccepted to ApJ Letters

References in corpus (43)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Astropy: A Community Python Package for Astronomy
• The NumPy array: a structure for efficient numerical computation
• The Gaia mission
• Validation of the new Hipparcos reduction
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• Gaia Data Release 2: The astrometric solution
• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• Gaia Early Data Release 3: The astrometric solution
• REBOUND: An open-source multi-purpose N-body code for collisional dynamics
• Images of a fourth planet orbiting HR 8799
• IAS15: A fast, adaptive, high-order integrator for gravitational dynamics, accurate to machine precision over a billion orbits
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• BANYAN. XI. The BANYAN $\Sigma$ multivariate Bayesian algorithm to identify members of young associations within 150 pc
• A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood
• On the Luminosity of Young Jupiters
• Fundamental Parameters and Spectral Energy Distributions of Young and Field Age Objects with Masses Spanning the Stellar to Planetary Regime
• The Deuterium-Burning Mass Limit for Brown Dwarfs and Giant Planets
• A Combined Subaru/VLT/MMT 1--5 Micron Study of Planets Orbiting HR 8799: Implications for Atmospheric Properties, Masses, and Formation
• The Tucana/Horologium, Columba, AB Doradus, and Argus Associations: New Members and Dusty Debris Disks
• The Hipparcos-Gaia Catalog of Accelerations
• Retrieving scattering clouds and disequilibrium chemistry in the atmosphere of HR 8799e
• Individual Dynamical Masses of Ultracool Dwarfs
• Constraining the initial entropy of directly-detected exoplanets
• Stability of the directly imaged multiplanet system HR 8799: resonance and masses
• First direct detection of an exoplanet by optical interferometry; Astrometry and K-band spectroscopy of HR8799 e
• Dynamical Constraints on the HR 8799 Planets with GPI
• Reconnaissance of the HR 8799 Exosolar System II: Astrometry and Orbital Motion
• Astrometric Monitoring of the HR 8799 Planets: Orbit Constraints from Self-Consistent Measurements
• Evolution of Gas Giant Entropy During Formation by Runaway Accretion
• LBT observations of the HR 8799 planetary system: First detection of HR8799e in H band
• Precise Dynamical Masses and Orbital Fits for $\beta$ Pic b and $\beta$ Pic c
• High-Mass, Four-Planet Models for HR 8799: Constraining the Orbital Inclination and Age of the System
• The Planetary Accretion Shock. II. Grid of Post-Shock Entropies and Radiative Shock Efficiencies for Non-Equilibrium Radiation Transport
• A search for a 5th planet around HR 8799 using the star-hopping RDI technique at VLT/SPHERE
• A detailed characterization of HR 8799's debris disk with ALMA in Band 7
• On the Chemical Abundance of HR 8799 and the Planet c
• An exact, generalised Laplace resonance in the HR 8799 planetary system
• Hot Start Giant Planets Form With Radiative Interiors
• Producing a BOSS-CMASS sample with DES imaging
• The orbital architecture and debris disks of the HR 8799 planetary system
• Long-term stability of the HR 8799 planetary system without resonant lock
• Enrichment of the HR 8799 planets by minor bodies and dust

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• MADYS: the Manifold Age Determination for Young Stars
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• Applying a temporal systematics model to vector Apodizing Phase Plate coronagraphic data: TRAP4vAPP
• Constraints on Planets in Nearby Young Moving Groups Detectable by High-Contrast Imaging and Gaia Astrometry
• PACOME: Optimal multi-epoch combination of direct imaging observations for joint exoplanet detection and orbit estimation
• SCExAO/CHARIS and Gaia Direct Imaging and Astrometric Discovery of a Superjovian Planet 3--4 lambda/D from the Accelerating Star HIP 54515
• htof: A new open-source tool for analyzing Hipparcos, Gaia, and future astrometric missions
• The orbital architecture and stability of the $\mu$ Arae planetary system
• L-band Integral Field Spectroscopy of the HR 8799 Planetary System
• A search for transits among the δ Scuti variables in Kepler