Dust production and depletion in evolved planetary systems

Farihi, Jay; Lieshout, R. Van; Cauley, P. Wilson; Dennihy, E.; Su, Kate; Kenyon, Scott J.; Wilson, T. G.; Toloza, Odette; Gänsicke, B. T.; Hippel, Ted von; Redfield, Seth; Debes, John H.; Xu, Siyi; Rogers, Laura K.; Bonsor, Amy; Swan, Andrew; Pala, A. F.; Reach, W. T.

doi:10.1093/mnras/sty2331

Cited by 49 publications

(71 citation statements)

References 83 publications

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“…The cause is unclear due to the sparse sampling of WISE and the variability could either come from the transits or the disk material. Infrared variability of white dwarf dust disks has been reported up to 30% at the IRAC bands (Xu & Jura 2014;Xu et al 2018b;Farihi et al 2018) and the proposed scenario is tidal disruption and dust production/destruction. It is evident that dust is constantly produced and destroyed around WD 1145+017 a The first number is for the UVB arm while the second number is for the VIS arm.…”

Section: 5µm and Optical Transitsmentioning

confidence: 99%

Shallow Ultraviolet Transits of WD 1145+017

Hallakoun

Gary³

et al. 2019

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WD 1145+017 is a unique white dwarf system that has a heavily polluted atmosphere, an infrared excess from a dust disk, numerous broad absorption lines from circumstellar gas, and changing transit features, likely from fragments of an actively disintegrating asteroid. Here, we present results from a large photometric and spectroscopic campaign with Hubble, Keck , VLT, Spitzer, and many other smaller telescopes from 2015 to 2018. Somewhat surprisingly, but consistent with previous observations in the u' band, the UV transit depths are always shallower than those in the optical. We develop a model that can quantitatively explain the observed "bluing" and the main findings are: I. the transiting objects, circumstellar gas, and white dwarf are all aligned along our line of sight; II. the transiting object is blocking a larger fraction of the circumstellar gas than of the white dwarf itself. Because most circumstellar lines are concentrated in the UV, the UV flux appears to be less blocked compared to the optical during a transit, leading to a shallower UV transit. This scenario is further supported by the strong anti-correlation between optical transit depth

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Section: 5µm and Optical Transitsmentioning

confidence: 99%

Shallow Ultraviolet Transits of WD 1145+017

Hallakoun

Gary³

et al. 2019

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“…Debes & Sigurdsson 2002;Veras et al 2011;Veras 2016;Mustill et al 2018). Besides, if migration or scattering occurs towards the proximity of the Roche limit, strong tidal forces can further crush the planetary cores (Farihi et al 2018), like in the case of the planetesimal found shattering around WD 1145+017 (Vanderburg et al 2015). Such a fragmentation process consequently enables the formation of a debris disc, made of metal-rich planetary material, which could in turn accrete onto the WD, polluting its atmosphere (e.g.…”

Section: Introductionmentioning

confidence: 99%

Circumbinary exoplanets and brown dwarfs with the Laser Interferometer Space Antenna

Danielski

Korol

Rossi

2019

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Aims. We explore the prospects for the detection of giant circumbinary exoplanets and brown dwarfs (BDs) orbiting Galactic double white dwarfs binaries (DWDs) with the Laser Interferometer Space Antenna (LISA). Methods. By assuming an occurrence rate of 50%, motivated by white dwarf pollution observations, we built a Galactic synthetic population of P-type giant exoplanets and BDs orbiting DWDs. We carried this out by injecting different sub-stellar populations, with various mass and orbital separation characteristics, into the DWD population used in the LISA mission proposal. We then performed a Fisher matrix analysis to measure how many of these three-body systems show a periodic Doppler-shifted gravitational wave perturbation detectable by LISA. Results. We report the number of circumbinary planets (CBPs) and (BDs) that can be detected by LISA for various combinations of mass and semi-major axis distributions. We identify pessimistic and optimistic scenarios corresponding, respectively, to 3 and 83 (14 and 2218) detections of CBPs (BDs), observed during the length of the nominal LISA mission. These detections are distributed all over the Galaxy following the underlying DWD distribution, and they are biased towards DWDs with higher LISA signal-to-noise ratio and shorter orbital period. Finally, we show that if LISA were to be extended for four more years, the number of systems detected will be more than doubled in both the optimistic and pessimistic scenarios. Conclusions. Our results present promising prospects for the detection of post-main sequence exoplanets and BDs, showing that gravitational waves can prove the existence of these populations over the totality of the Milky Way. Detections by LISA will deepen our knowledge on the life of exoplanets subsequent to the most extreme evolution phases of their hosts, clarifying whether new phases of planetary formation take place later in the life of the stars. Such a method is strongly complementary to electromagnetic studies within the solar region and opens a window into the investigation of planets and BDs everywhere in the entire Galaxy, and possibly even in nearby galaxies in the Local Group. Evidences for sub-stellar objects around WDs White dwarf pollutionWhite dwarfs are expected to have a pure H or He atmosphere (Schatzman 1945) and their high surface gravity (∼ 10 5 denser than the Sun) makes the sinking metals diffusion timescale several order of magnitude shorter than the evolutionary period. Yet, observations show the presence of heavy elements in the spectra of 25% to 50% of all observed WDs (Zuckerman et al. 2003(Zuckerman et al. , 2010Koester et al. 2014), indicating that a continuous supply Article number, page 1 of 16

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“…WD 0408−041 (GD56) has previously been observed with dust emission variations at 3-5 µm showing brightening and dimming with peak-to-peak changes of 20% over 11.2 yrs (Farihi et al 2018). This was attributed to dust production and consequentially depletion.…”

Section: Wd 0408−041mentioning

confidence: 86%

“…A light curve of WD 0408−041 showing the UKIRT K band data, and the Spitzer /WISE data at whichFarihi et al (2018) observed a drop in the mid-infrared flux. The grey regions represent the 1 and 3 σ median variability constraint for the K band, and then scaled up to Spitzer wavelengths using equations 1 and 2 (assuming a constant colour temperature).…”

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Near-infrared variability in dusty white dwarfs: tracing the accretion of planetary material

Rogers

Bonsor

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The inwards scattering of planetesimals towards white dwarfs is expected to be a stochastic process with variability on human time-scales. The planetesimals tidally disrupt at the Roche radius, producing dusty debris detectable as excess infrared emission. When sufficiently close to the white dwarf, this debris sublimates and accretes on to the white dwarf and pollutes its atmosphere. Studying this infrared emission around polluted white dwarfs can reveal how this planetary material arrives in their atmospheres. We report a near-infrared monitoring campaign of 34 white dwarfs with infrared excesses with the aim to search for variability in the dust emission. Time series photometry of these white dwarfs from the United Kingdom Infrared Telescope (Wide Field Camera) in the J, H and K bands were obtained over baselines of up to three years. We find no statistically significant variation in the dust emission in all three near-infrared bands. Specifically, we can rule out variability at ∼ 1.3% for the 13 white dwarfs brighter than 16th mag in K band, and at ∼ 10% for the 32 white dwarfs brighter than 18th mag over time-scales of three years. Although to date two white dwarfs, SDSS J095904.69−020047.6 and WD 1226+110, have shown K band variability, in our sample we see no evidence of new K band variability at these levels. One interpretation is that the tidal disruption events which lead to large variabilities are rare, occur on short time-scales, and after a few years the white dwarfs return to being stable in the near-infrared.

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Dust production and depletion in evolved planetary systems

Cited by 49 publications

References 83 publications

Shallow Ultraviolet Transits of WD 1145+017

Shallow Ultraviolet Transits of WD 1145+017

Circumbinary exoplanets and brown dwarfs with the Laser Interferometer Space Antenna

Near-infrared variability in dusty white dwarfs: tracing the accretion of planetary material

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