A New Method for Finding Nearby White Dwarf Exoplanets and Detecting Biosignatures

Abstract

We demonstrate that the James Webb Space Telescope (JWST) can detect infrared (IR) excess from the blended light spectral energy distribution of spatially unresolved terrestrial exoplanets orbiting nearby white dwarfs. We find that JWST is capable of detecting warm (habitable-zone; T${}_{\mathrm{eq}}$=287 K) Earths or super-Earths and hot (400-1000 K) Mercury analogs in the blended light spectrum around the nearest 15 isolated white dwarfs with 10 hrs of integration per target using MIRI's Medium Resolution Spectrograph (MRS). Further, these observations constrain the presence of a CO${}_2$-dominated atmosphere on these planets. The technique is nearly insensitive to system inclination, and thus observation of even a small sample of white dwarfs could place strong limits on the occurrence rates of warm terrestrial exoplanets around white dwarfs in the solar neighborhood. We find that JWST can also detect exceptionally cold (100-150 K) Jupiter-sized exoplanets via MIRI broadband imaging at $\lambda =21\mu \mathrm{m}$ for the 34 nearest ($<13$ pc) solitary white dwarfs with 2 hrs of integration time per target. Using IR excess to detect thermal variations with orbital phase or spectral absorption features within the atmosphere, both of which are possible with long-baseline MRS observations, would confirm candidates as actual exoplanets. Assuming an Earth-like atmospheric composition, we find that the detection of the biosignature pair O${}_3$+CH${}_4$ is possible for all habitable-zone Earths (within 6.5 pc; six white dwarf systems) or super-Earths (within 10 pc; 17 systems) orbiting white dwarfs with only 5-36 hrs of integration using MIRI's Low Resolution Spectrometer (LRS).

arXiv commentAccepted to MNRAS

References in corpus (93)

• The Spitzer Space Telescope Mission
• Habitable Zones Around Main-Sequence Stars: New Estimates
• Precipitating Condensation Clouds in Substellar Atmospheres
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• A Tidally-Disrupted Asteroid Around the White Dwarf G29-38
• A disintegrating minor planet transiting a white dwarf
• Are There Unstable Planetary Systems Around White Dwarfs?
• Neglected Clouds in T and Y Dwarf Atmospheres
• A $Gaia$ Data Release 2 catalogue of white dwarfs and a comparison with SDSS
• Astrometric exoplanet detection with Gaia
• Ancient planetary systems are orbiting a large fraction of white dwarf stars
• A catalogue of white dwarfs in Gaia EDR3
• Exoplanet Biosignatures: Understanding Oxygen as a Biosignature in the Context of Its Environment
• The White Dwarf Initial-Final Mass Relation for Progenitor Stars From 0.85 to 7.5 M${}_{\odot }$
• Reflected Spectra and Albedos of Extrasolar Giant Planets I: Clear and Cloudy Atmospheres
• A Young White Dwarf Companion to Pulsar 1620-26: Evidence for Early Planet Formation
• Thermal Emission and Albedo Spectra of Super Earths with Flat Transmission Spectra
• Hubble Space Telescope Astrometry of the Procyon System
• Precise Radial Velocities of Giant Stars VII. Occurrence Rate of Giant Extrasolar Planets as a Function of Mass and Metallicity
• Absence of a thick atmosphere on the terrestrial exoplanet LHS 3844b
• The Detectability and Characterization of the TRAPPIST-1 Exoplanet Atmospheres with JWST
• Know Your Neighborhood: A Detailed Model Atmosphere Analysis of Nearby White Dwarfs
• Tidal Locking of Habitable Exoplanets
• Techniques and Review of Absolute Flux Calibration from the Ultraviolet to the Mid-Infrared
• Water Clouds in Y Dwarfs and Exoplanets
• Discovery of a Candidate for the Coolest Known Brown Dwarf
• A Giant Planet Candidate Transiting a White Dwarf
• A Dusty Disk Around GD 362, a White Dwarf With a Uniquely High Photospheric Metal Abundance
• Accretion of a giant planet onto a white dwarf
• On the Orbits of Low-mass Companions to White Dwarfs and the Fates of the Known Exoplanets
• DA white dwarfs in SDSS DR7 and a search for infrared excess emission
• The 100 pc White Dwarf Sample in the SDSS Footprint
• The frequency and infrared brightness of circumstellar discs at white dwarfs
• Analysis of Helium-Rich White Dwarfs Polluted by Heavy Elements in the Gaia Era
• Excess Infrared Radiation from a Massive DAZ White Dwarf: GD362 - a Debris Disk?
• The chemical diversity of exo-terrestrial planetary debris around white dwarfs
• High-contrast Imaging Search for Planets and Brown Dwarfs around the Most Massive Stars in the Solar Neighborhood
• $Gaia$ white dwarfs within 40 pc II: the volume-limited northern hemisphere sample
• Spitzer IRAC Observations of White Dwarfs. I. Warm Dust at Metal-Rich Degenerates
• Tidal Limits to Planetary Habitability
• Transit surveys for Earths in the habitable zones of white dwarfs
• A New Generation of Cool White Dwarf Atmosphere Models. I. Theoretical Framework and Applications to DZ Stars
• Habitable Planets Around White and Brown Dwarfs: The Perils of a Cooling Primary
• The Frequency of Debris Disks at White Dwarfs
• On the Direct Imaging of Tidally Heated Exomoons
• Prospects for Characterizing the Atmosphere of Proxima Centauri b
• Spitzer IRAC Observations of White Dwarfs. II. Massive Planetary and Cold Brown Dwarf Companions to Young and Old Degenerates
• A New Generation of Cool White Dwarf Atmosphere Models. IV. Revisiting the Spectral Evolution of Cool White Dwarfs
• Imaging planets around nearby white dwarfs
• A Jovian analogue orbiting a white dwarf star
• Model Atmosphere Analysis of Two Very Cool White Dwarfs
• Kepler and the seven dwarfs: detection of low-level day-timescale periodic photometric variations in white dwarfs
• A white dwarf accreting planetary material determined from X-ray observations
• Detecting bio-markers in habitable-zone earths transiting white dwarfs
• Infrared-excess white dwarfs in the Gaia 100 pc sample
• Planetary Systems Around White Dwarfs
• Cool Customers in the Stellar Graveyard I: Limits to Extrasolar Planets Around the White Dwarf G29-38
• Rotational period of WD1953-011 - a magnetic white dwarf with a star spot
• The White Dwarf Opportunity: Robust Detections of Molecules in Earth-like Exoplanet Atmospheres with the James Webb Space Telescope
• Cold giant planets evaporated by hot white dwarfs
• JWST Noise Floor II: Systematic Error Sources in JWST NIRCam Time Series
• A New Generation of Cool White Dwarf Atmosphere Models. II. A DZ Star with Collision-Induced Absorption
• Absolute Flux Calibration of the IRAC Instrument on the Spitzer Space Telescope using Hubble Space Telescope Flux Standards
• The habitability and detection of Earth-like planets orbiting cool white dwarfs
• Sub-percent Photometry: Faint DA White Dwarf Spectophotometric Standards for Astrophysical Observatories
• Differentiating Modern and Prebiotic Earth Scenarios for TRAPPIST-1e: High-resolution Transmission Spectra and Predictions for JWST
• Infrared Excesses around Bright White Dwarfs from Gaia and unWISE. II
• When flux standards go wild: white dwarfs in the age of Kepler
• The DODO Survey II: A Gemini Direct Imaging Search for Substellar and Planetary Mass Companions around Nearby Equatorial and Northern Hemisphere White Dwarfs
• A Dark Spot on a Massive White Dwarf
• SDSS J000555.90-100213.5: a hot, magnetic carbon-atmosphere WD rotating with a 2.1 day period
• High contrast imaging at 10 microns, a search for exoplanets around: Eps Indi A, Eps Eri, Tau Ceti, Sirius A and Sirius B
• Pressure Distortion of the H${}_2$-He Collision-Induced Absorption at the Photosphere of Cool White Dwarf Stars
• Spitzer IRAC Sparsely Sampled Phase Curve of the Exoplanet WASP-14b
• UV Surface Environments and Atmospheres of Earth-like Planets Orbiting White Dwarfs
• Cool Customers in the Stellar Graveyard IV: Spitzer Search for Mid-IR excesses Around Five DAs
• Cool white dwarfs as standards for infrared observations
• An Extreme-AO Search for Giant Planets around a White Dwarf --VLT/SPHERE performance on a faint target GD 50
• A Search for short-period Rocky Planets around WDs with the Cosmic Origins Spectrograph (COS)
• A New Method For Studying Exoplanet Atmospheres Using Planetary Infrared Excess
• Piercing the Glare: Direct Imaging Search for Planets in the Sirius System
• High-resolution Spectra and Biosignatures of Earth-like Planets Transiting White Dwarfs
• Infrared absorption of dense helium and its importance in the atmospheres of cool white dwarfs
• A study of the photometric variability of the peculiar magnetic white dwarf WD1953-011
• A Spitzer Search for Substellar Companions to Low Mass White Dwarfs
• Photometric precision of a Si:As impurity band conduction mid-infrared detector and application to transit spectroscopy
• A Young White Dwarf with an Infrared Excess
• Cool Customers in the Stellar Graveyard III: Limits to Substellar Objects around nearby White Dwarfs using CFHT
• Search for giant planets around seven white dwarfs in the Hyades cluster with the Hubble Space Telescope
• Confirming new white dwarf-ultracool dwarf binary candidates
• Retrieving Exoplanet Atmospheres using Planetary Infrared Excess: Prospects for the Nightside of WASP-43 b and other Hot Jupiters
• Finding rocky asteroids around white dwarfs by their periodic thermal emission
• An Imaging Search for Post-Main-Sequence Planets of Sirius B

Cited by in corpus (8)

• The Influence of Tidal Heating on the Habitability of Planets Orbiting White Dwarfs
• Heavy Dark Matter in White Dwarfs: Multiple-Scattering Capture and Thermalization
• The Fate of Oceans on First-Generation Planets Orbiting White Dwarfs
• Direct detectability of tidally heated exomoons by photometric orbital modulation
• TTV Constraints on Additional Planets in the WD 1856+534 system
• Serendipitous observation of a white dwarf companion to a JWST/MIRI coronagraphic calibrator
• General Relativity Can Prevent a Runaway Greenhouse on Potentially Habitable Planets Orbiting White Dwarfs
• Can local White Dwarfs constrain Dark Matter interactions?