Fast spectrophotometry of WD 1145+017

Abstract

WD 1145+017 is currently the only white dwarf known to exhibit periodic transits of planetary debris as well as absorption lines from circumstellar gas. We present the first simultaneous fast optical spectrophotometry and broad-band photometry of the system, obtained with the Gran Telescopio Canarias (GTC) and the Liverpool Telescope (LT), respectively. The observations spanned $5.5$ h, somewhat longer than the $4.5$-h orbital period of the debris. Dividing the GTC spectrophotometry into five wavelength bands reveals no significant colour differences, confirming grey transits in the optical. We argue that absorption by an optically thick structure is a plausible alternative explanation for the achromatic nature of the transits that can allow the presence of small-sized ($\sim \mu$m) particles. The longest ($87$ min) and deepest ($50$ per cent attenuation) transit recorded in our data exhibits a complex structure around minimum light that can be well modelled by multiple overlapping dust clouds. The strongest circumstellar absorption line, Fe II $\lambda$5169, significantly weakens during this transit, with its equivalent width reducing from a mean out-of-transit value of $2$ Å to $1$ Å in-transit, supporting spatial correlation between the circumstellar gas and dust. Finally, we made use of the Gaia Data Release 2 and archival photometry to determine the white dwarf parameters. Adopting a helium-dominated atmosphere containing traces of hydrogen and metals, and a reddening $E(B-V)=0.01$ we find $T_{\mathrm{eff}}=15020\pm 520$ K, $\log g=8.07\pm 0.07$, corresponding to $M_\mathrm{WD}=0.63\pm0.05\ \mbox{$\mathrm{M}_{\odot}$}$ and a cooling age of $224\pm 30$ Myr.

arXiv comment13 pages, 9 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society (2018 Aug 22)

References in corpus (43)

• Gaia Data Release 2. Summary of the contents and survey properties
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• The Pan-STARRS1 Photometric System
• A Tidally-Disrupted Asteroid Around the White Dwarf G29-38
• A Three-Dimensional Map of Milky-Way Dust
• A disintegrating minor planet transiting a white dwarf
• The frequency of planetary debris around young white dwarfs
• Ancient planetary systems are orbiting a large fraction of white dwarf stars
• The Initial-Final Mass Relation: Direct Constraints at the Low Mass End
• Accretion and diffusion in white dwarfs. New diffusion timescales and applications to GD362 and G29-38
• Three-dimensional mapping of the local interstellar medium with composite data
• The initial-final mass relationship of white dwarfs revisited: effect on the luminosity function and mass distribution
• Possible Disintegrating Short-Period Super-Mercury Orbiting KIC 12557548
• 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)
• Debris Disks Around White Dwarfs: The DAZ Connection
• The K2-ESPRINT Project. I. Discovery of the Disintegrating Rocky Planet K2-22b with a Cometary Head and Leading Tail
• KOI-2700b - A Planet Candidate With Dusty Effluents on a 22-Hour Orbit
• The Gaia 20 pc white dwarf sample
• DA white dwarfs in SDSS DR7 and a search for infrared excess emission
• The chemical diversity of exo-terrestrial planetary debris around white dwarfs
• Evolution of OH and CO-dark Molecular Gas Fraction Across a Molecular Cloud Boundary In Taurus
• Unstable low-mass planetary systems as drivers of white dwarf pollution
• Drifting Asteroid Fragments Around WD 1145+017
• High-speed photometry of the disintegrating planetesimals at WD1145+017: evidence for rapid dynamical evolution
• DB white dwarfs in the Sloan Digital Sky Survey Data Release 10 and 12
• White dwarfs in the UKIDSS Large Area Survey: The Substellar Companion Fraction
• Explaining the variability of WD 1145+017 with simulations of asteroid tidal disruption
• Updated parameters for the transiting exoplanet WASP-3b using RISE, a new fast camera for the Liverpool Telescope
• High resolution optical spectroscopy of Praesepe white dwarfs
• Multiwavelength Transit Observations of the Candidate Disintegrating Planetesimals Orbiting WD 1145+017
• Spectroscopic Evolution of Disintegrating Planetesimals: Minutes to Months Variability in the Circumstellar Gas Associated with WD 1145+017
• WD 1145+017 Photometric Observations During 8 Months of High Activity
• Gray transits of WD 1145+017 over the visible band
• Evidence for eccentric, precessing gaseous debris in the circumstellar absorption towards WD 1145+017
• A dearth of small particles in the transiting material around the white dwarf WD 1145+017
• Simultaneous infrared and optical observations of the transiting debris cloud around WD 1145+017
• Mass and eccentricity constraints on the planetary debris orbiting the white dwarf WD 1145+017
• RISE: a fast-readout imager for exoplanet transit timing
• WD 1145+017: Optical Activity During 2016-2017 and Limits on the X-Ray Flux
• Once in a blue moon: detection of 'bluing' during debris transits in the white dwarf WD1145+017
• Dynamical mass and multiplicity constraints on co-orbital bodies around stars
• Puoko-nui: a flexible high-speed photometric system

Cited by in corpus (23)

• I Spy Transits and Pulsations: Empirical Variability in White Dwarfs Using Gaia and the Zwicky Transient Facility
• The frequency of gaseous debris discs around white dwarfs
• Relentless and Complex Transits from a Planetesimal Debris Disk
• Circularization of tidal debris around white dwarfs: implications for gas production and dust variability
• The lifetimes of planetary debris discs around white dwarfs
• Detections and Constraints on White Dwarf Variability from Time-Series GALEX Observations
• Embedding planetesimals into white dwarf discs from large distances
• Constraining the origin of the planetary debris surrounding ZTF J0139+5245 through rotational fission of a triaxial asteroid
• High-eccentricity migration of planetesimals around polluted white dwarfs
• Orbital relaxation and excitation of planets tidally interacting with white dwarfs
• Shallow Ultraviolet Transits of WD 1145+017
• Necroplanetology: Simulating the Tidal Disruption of Differentiated Planetary Material Orbiting WD 1145+017
• Asynchronous accretion can mimic diverse white dwarf pollutants II: water content
• A CHEOPS White Dwarf Transit Search
• A transmission spectrum of the planet candidate WD 1856+534 b and a lower limit to its mass
• White dwarf planetary debris dependence on physical structure distributions within asteroid belts
• Search for gas from the disintegrating rocky exoplanet K2-22b
• WD 1145+017: Alternative models of the atmosphere, dust clouds, and gas rings
• Time resolved spectroscopy of dust and gas from extrasolar planetesimals orbiting WD 1145+017
• Planetesimals drifting through dusty and gaseous white dwarf debris discs: Types I, II and III-like migration
• White dwarf magnetospheres: Shielding volatile content of icy objects and implications for volatile pollution scarcity
• Disruption of exo-asteroids around white dwarfs and the release of dust particles in debris rings in co-orbital motion
• Extrasolar enigmas: from disintegrating exoplanets to exoasteroids