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

van Roestel, Jan and Kupfer, Thomas and Bell, Keaton J. and Burdge, Kevin and Mróz, Przemek and Prince, Thomas A. and Bellm, Eric C. and Drake, Andrew and Dekany, Richard and Mahabal, Ashish A. and Porter, Michael and Riddle, Reed and Shin, Kyung Min and Shupe, David L. (2021) ZTFJ0038+2030: a long period eclipsing white dwarf and a substellar companion. . (Unpublished)

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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 ± 0.02 M_⊙ and a temperature of 10900 ± 200 K. The companion has a mass of 0.059 ± 0.004 M_⊙ and a small radius of 0.0783 ± 0.0013 R_⊙. It is one of the smallest transiting brown dwarfs known and likely old, ≳8Gyr. 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.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
van Roestel, Jan0000-0002-2626-2872
Kupfer, Thomas0000-0002-6540-1484
Burdge, Kevin0000-0002-7226-836X
Mróz, Przemek0000-0001-7016-1692
Prince, Thomas A.0000-0002-8850-3627
Bellm, Eric C.0000-0001-8018-5348
Dekany, Richard0000-0002-5884-7867
Mahabal, Ashish A.0000-0003-2242-0244
Porter, Michael0000-0003-3168-5586
Riddle, Reed0000-0002-0387-370X
Shupe, David L.0000-0003-4401-0430
Additional Information:JvR is partially supported by NASA-LISA grant 76280NSSC19K0325. K.J.B. is supported by the National Science Foundation under Award AST-1903828. We thank Lars Bildsten for trading one hour of ESIKeck time. Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Grant No. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. Based on observations obtained with the 200-inch Hale Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. The Hale telescope is operated by the Caltech Optical Observatories. Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. This research has made use of the VizieR catalogue access tool, CDS, Strasbourg, France. This research made use of NumPy (Harris et al. 2020); matplotlib, a Python library for publication quality graphics (Hunter 2007); SciPy (Virtanen et al. 2020); Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2018, 2013a). This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. The Pan-STARRS1 Surveys (PS1) have been made possible through contributions of the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation under Grant No. AST-1238877, the University of Maryland, and Eotvos Lorand University (ELTE). Facilities: P48(ZTF), P200:5.0m (CHIMERA), Keck2:10m (ESI), Software: astropy (Astropy Collaboration et al. 2013b), Makee, ellc (Maxted et al. 2014), scipy, emcee (Foreman-Mackey et al. 2013)
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC), Zwicky Transient Facility
Funding AgencyGrant Number
ZTF partner institutionsUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Gaia Multilateral AgreementUNSPECIFIED
Subject Keywords:editorials, notices | miscellaneous | catalogs | surveys
Record Number:CaltechAUTHORS:20210604-142603248
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109401
Deposited By: George Porter
Deposited On:07 Jun 2021 14:38
Last Modified:07 Jun 2021 14:38

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