L-band Integral Field Spectroscopy of the HR 8799 Planetary System

Abstract

Understanding the physical processes sculpting the appearance of young gas-giant planets is complicated by degeneracies confounding effective temperature, surface gravity, cloudiness, and chemistry. To enable more detailed studies, spectroscopic observations covering a wide range of wavelengths is required. Here we present the first L-band spectroscopic observations of HR 8799 d and e and the first low-resolution wide bandwidth L-band spectroscopic measurements of HR 8799 c. These measurements were facilitated by an upgraded LMIRCam/ALES instrument at the LBT, together with a new apodizing phase plate coronagraph. Our data are generally consistent with previous photometric observations covering similar wavelengths, yet there exists some tension with narrowband photometry for HR 8799 c. With the addition of our spectra, each of the three innermost observed planets in the HR 8799 system have had their spectral energy distributions measured with integral field spectroscopy covering $\sim 0.9$ to $4.1\mu \mathrm{m}$. We combine these spectra with measurements from the literature and fit synthetic model atmospheres. We demonstrate that the bolometric luminosity of the planets is not sensitive to the choice of model atmosphere used to interpolate between measurements and extrapolate beyond them. Combining luminosity with age and mass constraints, we show that the predictions of evolutionary models are narrowly peaked for effective temperature, surface gravity, and planetary radius. By holding these parameters at their predicted values, we show that more flexible cloud models can provide good fits to the data while being consistent with the expectations of evolutionary models.

arXiv comment19 pages, 11 figures, accepted for publication in The Astronomical Journal; added reference, updated figure 6 and table 4

References in corpus (49)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Astropy: A Community Python Package for Astronomy
• Gaia Data Release 2. Summary of the contents and survey properties
• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• Evolutionary models for cool brown dwarfs and extrasolar giant planets. The case of HD 20945
• Angular Differential Imaging: a Powerful High-Contrast Imaging Technique
• Images of a fourth planet orbiting HR 8799
• The Theory of Brown Dwarfs and Extrasolar Giant Planets
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• VOSA: Virtual Observatory SED Analyzer. An application to the Collinder 69 open cluster
• On the Luminosity of Young Jupiters
• Detection of Carbon Monoxide and Water Absorption Lines in an Exoplanet Atmosphere
• The 0.8-14.5 micron Spectra of Mid-L to Mid-T Dwarfs: Diagnostics of Effective Temperature, Grain Sedimentation, Gas Transport, and Surface Gravity
• Clouds and Chemistry in the Atmosphere of Extrasolar Planet HR8799b
• A Combined Subaru/VLT/MMT 1--5 Micron Study of Planets Orbiting HR 8799: Implications for Atmospheric Properties, Masses, and Formation
• Masses, Radii, and Cloud Properties of the HR 8799 Planets
• Retrieving scattering clouds and disequilibrium chemistry in the atmosphere of HR 8799e
• A Patchy Cloud Model for the L to T Dwarf Transition
• Simultaneous Detection of Water, Methane and Carbon Monoxide in the Atmosphere of Exoplanet HR8799b
• First light of the VLT planet finder SPHERE. III. New spectrophotometry and astrometry of the HR8799 exoplanetary system
• Constraining the initial entropy of directly-detected exoplanets
• A Systematic Study of Departures from Chemical Equilibrium in the Atmospheres of Substellar Mass Objects
• Stability of the directly imaged multiplanet system HR 8799: resonance and masses
• First Light LBT AO Images of HR 8799 bcde at 1.65 and 3.3 Microns: New Discrepancies between Young Planets and Old Brown Dwarfs
• First light of the VLT planet finder SPHERE. IV. Physical and chemical properties of the planets around HR8799
• Directly Imaged L-T Transition Exoplanets in the Mid-Infrared
• Reconnaissance of the HR 8799 Exosolar System I: Near IR Spectroscopy
• M-band Imaging of the HR 8799 Planetary System Using an Innovative LOCI-based Background Subtraction Technique
• Spatially resolved spectroscopy of the exoplanet HR 8799 c
• Characterizing 51 Eri b from 1-5 $\mu$m: a partly-cloudy exoplanet
• The CHARA Array Angular Diameter of HR 8799 Favors Planetary Masses for Its Imaged Companions
• The Vector-APP: a Broadband Apodizing Phase Plate that yields Complementary PSFs
• The LEECH Exoplanet Imaging Survey: Characterization of the Coldest Directly Imaged Exoplanet, GJ 504 b, and Evidence for Super-Stellar Metallicity
• Deep Thermal Infrared Imaging of HR 8799 bcde: New Atmospheric Constraints and Limits on a Fifth Planet
• PynPoint: a modular pipeline architecture for processing and analysis of high-contrast imaging data
• The Measurement, Treatment, and Impact of Spectral Covariance and Bayesian Priors in Integral-Field Spectroscopy of Exoplanets
• GPI spectra of HR 8799 c, d, and e from 1.5 to 2.4$\mu$m with KLIP Forward Modeling
• On-sky performance analysis of the vector Apodizing Phase Plate coronagraph on MagAO/Clio2
• The First Dynamical Mass Measurement in the HR 8799 System
• On the Chemical Abundance of HR 8799 and the Planet c
• Detecting Water In the atmosphere of HR 8799 c with L-band High Dispersion Spectroscopy Aided By Adaptive Optics
• The vector-apodizing phase plate coronagraph: design, current performance, and future development
• Minimizing the polarization leakage of geometric-phase coronagraphs with multiple grating pattern combinations
• METIS: The Mid-infrared ELT Imager and Spectrograph
• Patterned liquid-crystal optics for broadband coronagraphy and wavefront sensing
• First Light with ALES: A 2-5 Micron Adaptive Optics Integral Field Spectrograph for the LBT
• First Images of the Protoplanetary Disk Around PDS 201
• L-band Spectroscopy with Magellan-AO/Clio2: First Results on Young Low-Mass Companions
• On-Sky Operations with the ALES Integral Field Spectrograph

Cited by in corpus (2)

• Retrieving C and O Abundance of HR 8799 c by Combining High- and Low-Resolution Data
• ISPY-NACO Imaging Survey for Planets around Young stars. The demographics of forming planets embedded in protoplanetary disks