WD 1145+017: Optical Activity During 2016-2017 and Limits on the X-Ray Flux

Abstract

WD 1145+017 was observed from 2016 November through 2017 June for the purpose of further characterizing the transit behavior of the dusty debris clouds orbiting this white dwarf. The optical observations were carried out with a small ground-based telescope run by an amateur astronomer, and covered 53 different nights over the 8-month interval. We have found that the optical activity has increased to the highest level observed since its discovery with Kepler K2, with approximately 17% of the optical flux extinguished per orbit. The source exhibits some transits with depths of up to 55% and durations as long as two hours. The dominant period of the orbiting dust clouds during 2016-2017 is 4.49126 hours. We present 'waterfall' images for the entire 2016-2017 and 2015-2016 observing seasons. In addition, the white dwarf was observed with the Chandra X-ray Observatory for 10-ksec on each of four different occasions, separated by about a month each. The upper limit on the average X-ray flux from WD 1145+017 is ~5 x 10^{-15} ergs/cm^2/s (unabsorbed over the range 0.1-100 keV), which translates to an upper limit on the X-ray luminosity, Lx, of ~2 x 10^{28} ergs/s. If Lx = G Mwd Mdot/Rwd, where Mwd and Rwd are the mass and radius of the white dwarf, and Mdot is the accretion rate, then Mdot < 2 x 10^{11} g/s. This is just consistent with the value of Mdot that is inferred from the level of dust activity.

14 pages, 8 figures, submitted to MNRAS

References in corpus (10)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• The frequency of planetary debris around young white dwarfs
• Debris Disks Around White Dwarfs: The DAZ Connection
• The frequency and infrared brightness of circumstellar discs at white dwarfs
• Numerical Simulations of Collisional Cascades at the Roche Limits of White Dwarf Stars
• Explaining the variability of WD 1145+017 with simulations of asteroid tidal disruption
• WD 1145+017 Photometric Observations During 8 Months of High Activity
• Mass and eccentricity constraints on the planetary debris orbiting the white dwarf WD 1145+017
• Magnetospherically-trapped dust and a possible model for the unusual transits at WD 1145+017
• XMM-Newton Observations of the Cataclysmic Variable GW Lib

Cited by in corpus (14)

• 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
• Circularization of tidal debris around white dwarfs: implications for gas production and dust variability
• A dearth of small particles in the transiting material around the white dwarf WD 1145+017
• Modeling of the Variable Circumstellar Absorption Features of WD 1145+017
• The lifetimes of planetary debris discs around white dwarfs
• Orbital relaxation and excitation of planets tidally interacting with white dwarfs
• Shallow Ultraviolet Transits of WD 1145+017
• Survivability of radio-loud planetary cores orbiting white dwarfs
• WD 1145+017: Alternative models of the atmosphere, dust clouds, and gas rings
• Minimum Orbital Periods of H-Rich Bodies
• Planetesimals drifting through dusty and gaseous white dwarf debris discs: Types I, II and III-like migration
• Disruption of exo-asteroids around white dwarfs and the release of dust particles in debris rings in co-orbital motion