A dearth of small particles in the transiting material around the white dwarf WD 1145+017
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White dwarf WD 1145+017 is orbited by several clouds of dust, possibly emanating from actively disintegrating bodies. These dust clouds reveal themselves through deep, broad, and evolving transits in the star’s light curve. Here, we report two epochs of multi-wavelength photometric observations of WD 1145+017, including several filters in the optical, Ks and 4.5 μm bands in 2016 and 2017. The observed transit depths are different at these wavelengths. However, after correcting for excess dust emission at Ks and 4.5 μm, we find the transit depths for the white dwarf itself are the same at all wavelengths, at least to within the observational uncertainties of ∼5%-10%. From this surprising result, and under the assumption of low optical depth dust clouds, we conclude that there is a deficit of small particles (with radii s ≲ 1.5 μm) in the transiting material. We propose a model wherein only large particles can survive the high equilibrium temperature environment corresponding to 4.5 hr orbital periods around WD 1145+017, while small particles sublimate rapidly. In addition, we evaluate dust models that are permitted by our measurements of infrared emission.
Xu , S , Rappaport , S , van Lieshout , R , Vanderburg , A , Gary , B , Hallakoun , N , Ivanov , V D , Wyatt , M C , DeVore , J , Bayliss , D , Bento , J , Bieryla , A , Cameron , A , Cann , J M , Croll , B , Collins , K A , Dalba , P A , Debes , J , Doyle , D , Dufour , P , Ely , J , Espinoza , N , Joner , M D , Jura , M , Kaye , T , McClain , J L , Muirhead , P , Palle , E , Panka , P A , Provencal , J , Randall , S , Rodriguez , J E , Scarborough , J , Sefako , R , Shporer , A , Strickland , W , Zhou , G & Zuckerman , B 2018 , ' A dearth of small particles in the transiting material around the white dwarf WD 1145+017 ' Monthly Notices of the Royal Astronomical Society , vol 474 , no. 4 , pp. 4795-4809 . DOI: 10.1093/mnras/stx3023
Monthly Notices of the Royal Astronomical Society
© 2017, the Author(s). This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1093/mnras/stx3023
Funding: UK STFC grant ST/M001296/1 (AC).
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