A White Dwarf with Transiting Circumstellar Material Far Outside the Roche Limit

Abstract

We report the discovery of a white dwarf exhibiting deep, irregularly shaped transits, indicative of circumstellar planetary debris. Using Zwicky Transient Facility DR2 photometry of ZTFJ013906.17+524536.89 and follow-up observations from the Las Cumbres Observatory, we identify multiple transit events that recur every $\approx 107.2$d, much longer than the $4.5-4.9$h orbital periods observed in WD1145+017, the only other white dwarf known with transiting planetary debris. The transits vary in both depth and duration, lasting $15-25$d and reaching $20-45\%$ dips in flux. Optical spectra reveal strong Balmer lines, identifying the white dwarf as a DA with $T_{\mathrm{eff}}=10,530\pm 140\mathrm{K}$ and $\log (g)=7.86\pm 0.06$. A $\mathrm{Ca}\mathrm{II}\mathrm{K}$ absorption feature is present in all spectra both in and out of transit. Spectra obtained during one night at roughly $15\%$ transit depth show increased $\mathrm{Ca}\mathrm{II}\mathrm{K}$ absorption with a model atmospheric fit suggesting $[Ca/H]=-4.6\pm 0.3$, whereas spectra taken on three nights out of transit have $[Ca/H]$ of -5.5, -5.3, and -4.9 with similar uncertainties. While the $\mathrm{Ca}\mathrm{II}\mathrm{K}$ line strength varies by only 2-sigma, we consider a predominantly interstellar origin for Ca absorption unlikely. We suggest a larger column density of circumstellar metallic gas along the line of site or increased accretion of material onto the white dwarf's surface are responsible for the Ca absorption, but further spectroscopic studies are required. In addition, high-speed time series photometry out of transit reveals variability with periods of 900 and 1030s, consistent with ZZ Ceti pulsations.

arXiv commentSubmitted to ApJ, Accepted May 26, 2020. 5 Figures, 1 Table

References in corpus (66)

• Astropy: A Community Python Package for Astronomy
• Gaia Data Release 2. Summary of the contents and survey properties
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• Correcting for the Effects of Interstellar Extinction
• The Galaxy Evolution Explorer: A Space Ultraviolet Survey Mission
• The Zwicky Transient Facility: System Overview, Performance, and First Results
• Gaia Data Release 2: The astrometric solution
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey
• The Zwicky Transient Facility: Data Processing, Products, and Archive
• Las Cumbres Observatory Global Telescope Network
• The Wavelength Dependence of Interstellar Extinction from 1.25 to 8.0 microns Using GLIMPSE Data
• The UKIRT Infrared Deep Sky Survey ZYJHK Photometric System: Passbands and Synthetic Colours
• Gaia Data Release 2: Photometric content and validation
• Density of asteroids
• A Tidally-Disrupted Asteroid Around the White Dwarf G29-38
• The Hawaii Infrared Parallax Program. I. Ultracool Binaries and the L/T Transition
• The Formation Rate, Mass and Luminosity Functions of DA White Dwarfs from the Palomar Green Survey
• A disintegrating minor planet transiting a white dwarf
• Are There Unstable Planetary Systems Around White Dwarfs?
• An Improved Spectroscopic Analysis of DA White Dwarfs from the Sloan Digital Sky Survey Data Release 4
• The frequency of planetary debris around young white dwarfs
• A $Gaia$ Data Release 2 catalogue of white dwarfs and a comparison with SDSS
• The On-Orbit Performance of the Galaxy Evolution Explorer
• Ancient planetary systems are orbiting a large fraction of white dwarf stars
• The Pan-STARRS 1 Photometric Reference Ladder, Release 12.0
• Planet Hunters X. KIC 8462852 - Where's the Flux?
• The Link Between Planetary Systems, Dusty White Dwarfs, and Metal Polluted White Dwarfs
• Three-dimensional mapping of the local interstellar medium with composite data
• Circumstellar Debris and Pollution at White Dwarf Stars
• Foretellings of Ragnarök: World-engulfing Asymptotic Giants and the Inheritance of White Dwarfs
• Spectroscopic analysis of DA white dwarfs with 3D model atmospheres
• Probing The Lower Mass Limit for Supernova Progenitors and the High-Mass End of the Initial-Final Mass Relation from White Dwarfs in the Open Cluster M35 (NGC 2168)
• Formation of planetary debris discs around white dwarfs I: Tidal disruption of an extremely eccentric asteroid
• Survival of a brown dwarf after engulfment by a red giant star
• Eccentric Planets and Stellar Evolution as a Cause of Polluted White Dwarfs
• Accretion of a giant planet onto a white dwarf
• The UKIRT Hemisphere Survey: Definition and J-band Data Release
• The Zwicky Transient Facility Alert Distribution System
• DA white dwarfs in SDSS DR7 and a search for infrared excess emission
• The Roche limit for close-orbiting planets: Minimum density, composition constraints, and application to the 4.2-hour planet KOI 1843.03
• The accretion-diffusion scenario for metals in cool white dwarfs
• Post common envelope binaries from SDSS. XII: The orbital period distribution
• The chemical diversity of exo-terrestrial planetary debris around white dwarfs
• Unstable low-mass planetary systems as drivers of white dwarf pollution
• Detectable close-in planets around white dwarfs through late unpacking
• Monte Carlo simulations of post-common-envelope white dwarf + main sequence binaries: comparison with the SDSS DR7 observed sample
• High-speed photometry of the disintegrating planetesimals at WD1145+017: evidence for rapid dynamical evolution
• The unbiased frequency of planetary signatures around single and binary white dwarfs using $Spitzer$ and $Hubble$
• Ensemble Characteristics of the ZZ Ceti stars
• Numerical Simulations of Collisional Cascades at the Roche Limits of White Dwarf Stars
• The ELM Survey. VI. Eleven New Double Degenerates
• White Dwarf Pollution by Asteroids from Secular Resonances
• Convective Overshoot and Macroscopic Diffusion in Pure-Hydrogen Atmosphere White Dwarfs
• Spectroscopic Evolution of Disintegrating Planetesimals: Minutes to Months Variability in the Circumstellar Gas Associated with WD 1145+017
• A search for planetary eclipses of white dwarfs in the Pan-STARRS1 medium-deep fields
• The evolution of the self-lensing binary KOI-3278: evidence of extra energy sources during CE evolution
• WD 1145+017: Optical Activity During 2016-2017 and Limits on the X-Ray Flux
• Constraining the origin of the planetary debris surrounding ZTF J0139+5245 through rotational fission of a triaxial asteroid
• Discovery of Photospheric Calcium Line Strength Variations in the DAZd White Dwarf G29-38
• A Second Look at the Metal Line Variability of G29-38
• Deep Long Asymmetric Occultation in EPIC 204376071
• Chaotic rotation and evolution of asteroids and small planets in high-eccentricity orbits around white dwarfs
• Pulsational Mapping of Calcium Across the Surface of a White Dwarf
• The KIC 8462852 Light Curve From 2015.75 to 2018.18 Shows a Variable Secular Decline

Cited by in corpus (72)

• A Giant Planet Candidate Transiting a White Dwarf
• Current challenges in the physics of white dwarf stars
• I Spy Transits and Pulsations: Empirical Variability in White Dwarfs Using Gaia and the Zwicky Transient Facility
• Recurring Planetary Debris Transits and Circumstellar Gas around White Dwarf ZTF J0328$-$1219
• Relentless and Complex Transits from a Planetesimal Debris Disk
• A detailed analysis of the Gl 486 planetary system
• Horizontal spreading of planetary debris accreted by white dwarfs
• A road-map to white dwarf pollution: Tidal disruption, eccentric grind-down, and dust accretion
• Five New Post-Main-Sequence Debris Disks with Gaseous Emission
• 3D spectroscopic analysis of helium-line white dwarfs
• Low-Cost Access to the Deep, High-Cadence Sky: the Argus Optical Array
• Exocomets from a Solar System Perspective
• No evidence for a strong decrease of planetesimal accretion in old white dwarfs
• Do instabilities in high-multiplicity systems explain the existence of close-in white dwarf planets?
• Icy Exomoons Evidenced by Spallogenic Nuclides in Polluted White Dwarfs
• The ZTF Source Classification Project: I. Methods and Infrastructure
• New chondritic bodies identified in eight oxygen-bearing white dwarfs
• Understanding the origin of white dwarf atmospheric pollution by dynamical simulations based on detected three-planet systems
• Single magnetic white dwarfs with Balmer emission lines: A small class with consistent physical characteristics as possible signposts for close-in planetary companions
• Collisions in a gas-rich white dwarf planetary debris disc
• Accretion of tidally disrupted asteroids onto white dwarfs: direct accretion versus disk processing
• High-eccentricity migration of planetesimals around polluted white dwarfs
• Where are the Extrasolar Mercuries?
• A DZ white dwarf with a 30 MG magnetic field
• Asynchronous accretion can mimic diverse white dwarf pollutants I: core and mantle fragments
• The Geometry of the G29-38 White Dwarf Dust Disk from Radiative Transfer Modeling
• Secular chaos in white-dwarf planetary systems: origins of metal pollution and short-period planetary companions
• Dynamical evolution of two-planet systems and its connection with white dwarf atmospheric pollution
• Orbit decay of 2-100 au planetary remnants around white dwarfs with no gravitational assistance from planets
• On the role of resonances in polluting white dwarfs by asteroids
• TOI-1259Ab -- a gas giant planet with 2.7% deep transits and a bound white dwarf companion
• Formation of eccentric gas discs from sublimating or partially disrupted asteroids orbiting white dwarfs
• The Large Array Survey Telescope -- Science Goals
• The entry geometry and velocity of planetary debris into the Roche sphere of a white dwarf
• A CHEOPS White Dwarf Transit Search
• The smallest planetary drivers of white dwarf pollution
• Astrometric Gravitational-Wave Detection via Stellar Interferometry
• Spectral analysis of cool white dwarfs accreting from planetary systems: from the UV to the optical
• A transmission spectrum of the planet candidate WD 1856+534 b and a lower limit to its mass
• Four new deeply-eclipsing white dwarfs in ZTF
• White dwarf planetary debris dependence on physical structure distributions within asteroid belts
• Gemini/GMOS Transmission Spectroscopy of the Grazing Planet Candidate WD 1856+534 b
• Mysterious Dust-emitting Object Orbiting TIC 400799224
• Velocity-imaging the rapidly precessing planetary disc around the white dwarf HE 1349-2305 using Doppler tomography
• Missing metals in DQ stars: A simple explanation
• Disentangling the parameter space: The role of planet multiplicity in triggering dynamical instabilities on planetary systems around white dwarfs
• The post-main-sequence fate of the HR 8799 planetary system
• WD 1145+017: Alternative models of the atmosphere, dust clouds, and gas rings
• Two New White Dwarfs With Variable Magnetic Balmer Emission Lines
• The Effect of a Magnetic Field on the Dynamics of Debris Discs Around White Dwarfs
• Minimum Orbital Periods of H-Rich Bodies
• Can tidal evolution lead to close-in planetary bodies around white dwarfs I: Orbital period distribution
• Short-term stability of particles in the WD J0914+1914 white dwarf planetary system
• Can tidal evolution lead to close-in planetary bodies around white dwarfs II: volcanism and transits
• Infrared and Optical Detectability of Dyson Spheres at White Dwarf Stars
• Two substellar survivor candidates; one found and one missing
• Reinterpreting the Polluted White Dwarf SDSS J122859.93+104032.9 in Light of Thermohaline Mixing Models: More Polluting Material from a Larger Orbiting Solid Body
• Binary asteroid scattering around white dwarfs
• Small and Close-In Planets are Uncommon Around A-type Stars
• PM 1-322: new variable planetary nebula
• Characterizing planetary material accreted by cool helium atmosphere white dwarfs using an exponentially decaying disc model
• Planetesimals drifting through dusty and gaseous white dwarf debris discs: Types I, II and III-like migration
• Partial disruption of a planet around a white dwarf: the effect of perturbation from the remnant planet on the accretion
• Origin of Ca II emission around polluted white dwarfs
• The time-variable ultraviolet sky: Active Galactic Nuclei, Stars and White Dwarfs
• Gyr-timescale destruction of high-eccentricity asteroids by spin and why 2006 HY51 has been spared
• Wide sdB binaries. I. Orbital and atmospheric parameters
• Increased Surface Temperatures of Habitable White Dwarf Worlds Relative to Main-Sequence Exoplanets
• Tracing Planetary Accretion in a 3 Gyr-old Hydrogen-Rich White Dwarf: The Extremely Polluted Atmosphere of LSPM J0207+3331
• Disruption of exo-asteroids around white dwarfs and the release of dust particles in debris rings in co-orbital motion
• General Relativity Can Prevent a Runaway Greenhouse on Potentially Habitable Planets Orbiting White Dwarfs
• Identifying Periodic Variable Stars and Eclipsing Binary Systems with Long-Term Las Cumbres Observatory Photometric Monitoring of ZTF J0139+5245