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arXiv · 2105.08687

ZTFJ0038+2030: a long period eclipsing white dwarf and a substellar companion

Jan van Roestel·Thomas Kupfer·Keaton J. Bell·Kevin Burdge·Przemek Mróz·Thomas A. Prince·Eric C. Bellm·Andrew Drake·Richard Dekany·Ashish A. Mahabal·Michael Porter·Reed Riddle·Kyung Min Shin·David L. Shupe
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Abstract

In a search for eclipsing white dwarfs using the Zwicky Transient Facility lightcurves, we identified a deep eclipsing white dwarf with a dark, substellar companion. The lack of an infrared excess and an orbital period of 10 hours made this a potential exoplanet candidate. We obtained high-speed photometry and radial velocity measurements to characterize the system. The white dwarf has a mass of $0.50\pm0.02\,\mathrm{M_{\odot}}$ and a temperature of $10900\pm200\,$K. The companion has a mass of $0.059\pm0.004\,\mathrm{M_{\odot}}$ and a small radius of $0.0783\pm0.0013\,\mathrm{R_{\odot}}$. It is one of the smallest transiting brown dwarfs known and likely old, $\gtrsim 8\,$Gyr. The ZTF discovery efficiency of substellar objects transiting white dwarfs is limited by the number of epochs and as ZTF continues to collect data we expect to find more of these systems. This will allow us to measure period and mass distributions and allows us to understand the formation channels of white dwarfs with substellar companions.

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Jan van Roestel, Thomas Kupfer, Keaton J. Bell, Kevin Burdge, Przemek Mróz, Thomas A. Prince, Eric C. Bellm, Andrew Drake, Richard Dekany, Ashish A. Mahabal, Michael Porter, Reed Riddle, Kyung Min Shin, David L. Shupe. 2021-05-18. ZTFJ0038+2030: a long period eclipsing white dwarf and a substellar companion. https://doi.org/10.3847/2041-8213%2Fac22b7

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