A Search for short-period Rocky Planets around WDs with the Cosmic Origins Spectrograph (COS)

Abstract

The search for transiting habitable exoplanets has broadened to include several types of stars that are smaller than the Sun in an attempt to increase the observed transit depth and hence the atmospheric signal of the planet. Of all spectral types, white dwarfs are the most favorable for this type of investigation. The fraction of white dwarfs that possess close-in rocky planets is unknown, but several large angle stellar surveys have the photometric precision and cadence to discover at least one if they are common. Ultraviolet observations of white dwarfs may allow for detection of molecular oxygen or ozone in the atmosphere of a terrestrial planet. We use archival Hubble Space Telescope data from the Cosmic Origins Spectrograph to search for transiting rocky planets around UV-bright white dwarfs. In the process, we discovered unusual variability in the pulsating white dwarf GD 133, which shows slow sinusoidal variations in the UV. While we detect no planets around our small sample of targets, we do place stringent limits on the possibility of transiting planets, down to sub-lunar radii. We also point out that non-transiting small planets in thermal equilibrium are detectable around hotter white dwarfs through infrared excesses, and identify two candidates.

arXiv comment42 pages, 17 figures, accepted to ApJ

References in corpus (46)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• The Transiting Exoplanet Survey Satellite
• Analytic Lightcurves for Planetary Transit Searches
• The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey
• The Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)
• The Keck Planet Search: Detectability and the Minimum Mass and Orbital Period Distribution of Extrasolar Planets
• The Cosmic Origins Spectrograph
• A disintegrating minor planet transiting a white dwarf
• A gaseous metal disk around a white dwarf
• A Spectroscopic Survey & Analysis of Bright, Hydrogen-Rich White Dwarfs
• 3.6 and 4.5 Micron Phase Curves and Evidence for Non-Equilibrium Chemistry in the Atmosphere of Extrasolar Planet HD 189733b
• Giant Planet Companion to 2MASSW J1207334-393254
• Possible Disintegrating Short-Period Super-Mercury Orbiting KIC 12557548
• A sub-Mercury-sized exoplanet
• Large Amplitude Variations of an L/T Transition Brown Dwarf: Multi-Wavelength Observations of Patchy, High-Contrast Cloud Features
• Abiotic Ozone and Oxygen in Atmospheres Similar to Prebiotic Earth
• HST hot Jupiter transmission spectral survey: evidence for aerosols and lack of TiO in the atmosphere of WASP-12b
• Debris Disks Around White Dwarfs: The DAZ Connection
• Discovery and Validation of Kepler-452b: A 1.6-Re Super Earth Exoplanet in the Habitable Zone of a G2 Star
• Elemental Compositions of Two Extrasolar Rocky Planetesimals
• On the Orbits of Low-mass Companions to White Dwarfs and the Fates of the Known Exoplanets
• Variability in the super-Earth 55 Cnc e
• UBVRI Photometric Standard Stars Around the Sky at -50 Degrees Declination
• KOI-2700b - A Planet Candidate With Dusty Effluents on a 22-Hour Orbit
• Catastrophic Evaporation of Rocky Planets
• The First U.S. Naval Observatory Robotic Astrometric Telescope Catalog (URAT1)
• Understanding the Cool DA White Dwarf, G29-38
• Transit surveys for Earths in the habitable zones of white dwarfs
• Detectable close-in planets around white dwarfs through late unpacking
• Evryscope science: exploring the potential of all-sky gigapixel-scale telescopes
• Transmission spectrum of Earth as a transiting exoplanet - from the ultraviolet to the near-infrared
• Detecting industrial pollution in the atmospheres of earth-like exoplanets
• A Dusty Component to the Gaseous Debris Disk around the White Dwarf SDSS J1228+1040
• The WIRED Survey I: A Bright IR Excess Due to Dust Around the Heavily Polluted White Dwarf GALEX J193156.8+011745
• Kepler and the seven dwarfs: detection of low-level day-timescale periodic photometric variations in white dwarfs
• The WIRED Survey. IV. New Dust Disks from the McCook & Sion White Dwarf Catalog
• Transient outburst events from tidally disrupted asteroids near white dwarfs
• Multiwaveband photometry of the irradiated brown dwarf WD0137-349B
• Detecting bio-markers in habitable-zone earths transiting white dwarfs
• Mode identification of Pulsating White Dwarfs using the HST
• Kepler detection of a new extreme planetary system orbiting the subdwarf-B pulsator KIC10001893
• WD0837+185:the formation and evolution of an extreme mass ratio white dwarf-brown dwarf binary in Praesepe
• Transiting Planets with LSST I: Potential for LSST Exoplanet Detection
• SDSS J1152+0248: An eclipsing double white dwarf from the Kepler K2 campaign
• Discovery of Molecular Hydrogen in White Dwarf Atmospheres
• Finding rocky asteroids around white dwarfs by their periodic thermal emission

Cited by in corpus (16)

• Unstable low-mass planetary systems as drivers of white dwarf pollution
• I Spy Transits and Pulsations: Empirical Variability in White Dwarfs Using Gaia and the Zwicky Transient Facility
• The occurrence of planets and other substellar bodies around white dwarfs using K2
• The Fate of Exomoons in White Dwarf Planetary Systems
• Most white dwarfs with detectable dust discs show infrared variability
• Exoplanet recycling in massive white-dwarf debris discs
• Tidal circularization of gaseous planets orbiting white dwarfs
• Why are pulsar planets rare?
• A New Method for Finding Nearby White Dwarf Exoplanets and Detecting Biosignatures
• An empirical infrared transit spectrum of Earth: opacity windows and biosignatures
• Shallow Ultraviolet Transits of WD 1145+017
• Orbit decay of 2-100 au planetary remnants around white dwarfs with no gravitational assistance from planets
• Hydrodynamic Simulations of Disrupted Planetary Accretion Discs Inside the Core of an AGB Star
• Multi-wavelength observations of the EUV variable metal-rich white dwarf GD 394
• Precise determination of stellar parameters of the ZZ Ceti and DAZ white dwarf GD 133 through asteroseismology
• Just how hot are the $\omega$ Centauri extreme horizontal branch pulsators?