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Discovery and characterization of five new eclipsing AM CVn systems

van Roestel, J. and Kupfer, T. and Green, M. J. and Wong, T. L. S. and Bildsten, L. and Burdge, K. and Prince, T. and Marsh, T. R. and Szkody, P. and Fremling, C. and Graham, M. J. and Dhillon, V. S. and Littlefair, S. P. and Bellm, E. C. and Coughlin, M. and Duev, D. A. and Goldstein, D. A. and Laher, R. R. and Rusholme, B. and Riddle, R. and Dekany, R. and Kulkarni, S. R. (2022) Discovery and characterization of five new eclipsing AM CVn systems. Monthly Notices of the Royal Astronomical Society, 512 (4). pp. 5440-5461. ISSN 0035-8711. doi:10.1093/mnras/stab2421.

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AM CVn systems are ultra-compact, hydrogen-depleted, and helium-rich, accreting binaries with degenerate or semidegenerate donors. We report the discovery of five new eclipsing AM CVn systems with orbital periods of 61.5, 55.5, 53.3, 37.4, and 35.4 min. These systems were discovered by searching for deep eclipses in the Zwicky Transient Facility (ZTF) light curves of white dwarfs selected using Gaia parallaxes. We obtained phase-resolved spectroscopy to confirm that all systems are AM CVn binaries, and we obtained high-speed photometry to confirm the eclipse and characterize the systems. The spectra show double-peaked H e lines but also show metals, including K and Zn, elements that have never been detected in AM CVn systems before. By modelling the high-speed photometry, we measured the mass and radius of the donor star, potentially constraining the evolutionary channel that formed these AM CVn systems. We determined that the average mass of the accreting white dwarf is ≈0.8 M⊙, and that the white dwarfs in long-period systems are hotter than predicted by recently updated theoretical models. The donors have a high entropy and are a factor of ≈2 more massive compared to zero-entropy donors at the same orbital period. The large donor radius is most consistent with H e-star progenitors, although the observed spectral features seem to contradict this. The discovery of five new eclipsing AM CVn systems is consistent with the known observed AM CVn space density and estimated ZTF recovery efficiency.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ItemZTF data
van Roestel, J.0000-0002-2626-2872
Kupfer, T.0000-0002-6540-1484
Green, M. J.0000-0002-0948-4801
Wong, T. L. S.0000-0001-9195-7390
Bildsten, L.0000-0001-8038-6836
Burdge, K.0000-0002-7226-836X
Prince, T.0000-0002-8850-3627
Marsh, T. R.0000-0002-2498-7589
Szkody, P.0000-0003-4373-7777
Fremling, C.0000-0002-4223-103X
Graham, M. J.0000-0002-3168-0139
Dhillon, V. S.0000-0003-4236-9642
Littlefair, S. P.0000-0001-7221-855X
Bellm, E. C.0000-0001-8018-5348
Coughlin, M.0000-0002-8262-2924
Duev, D. A.0000-0001-5060-8733
Goldstein, D. A.0000-0003-3461-8661
Laher, R. R.0000-0003-2451-5482
Rusholme, B.0000-0001-7648-4142
Riddle, R.0000-0002-0387-370X
Dekany, R.0000-0002-5884-7867
Kulkarni, S. R.0000-0001-5390-8563
Additional Information:© 2021 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. Accepted 2021 August 19. Received 2021 August 19; in original form 2021 July 16. Published: 27 August 2021. JvR is partially supported by NASA-LISA grant 80NSSC19K0325. MJG was supported by the European Research Council (ERC) under the European Union’s FP7 Programme, grant no. 833031 (PI: Dan Maoz). VSD and HiPERCAM are supported by STFC. This research benefited from interactions at the ZTF Theory Network Meeting that were funded by the Gordon and Betty Moore Foundation through grant GBMF5076 and support from the National Science Foundation through PHY-1748958. Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the ZTF project. ZTF is supported by the National Science Foundation under grant no. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute of 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. 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. The research leading to these results has received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme numbers 677706 (WD3D) and 340040 (HiPERCAM). Based on observations made with the Gran Telescopio Canarias (GTC) installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias in the island of La Palma. Based on observations obtained at the international Gemini Observatory, a program of NSF’s NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). This research made use of matplotlib, a PYTHON library for publication quality graphics (Hunter 2007); NUMPY (Harris et al. 2020); Astroquery (Ginsburg et al. 2019); Astropy, a community-developed core PYTHON package for Astronomy (Astropy Collaboration 2018, 2013); and the VizieR catalogue access tool, CDS, Strasbourg, France. 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. Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the participating institutions. SDSS-IV acknowledges support and resources from the Center for High-Performance Computing at the University of Utah. The SDSS web site is SDSS-IV is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS Collaboration including the Brazilian Participation Group, the Carnegie Institution for Science, Carnegie Mellon University, the Chilean Participation Group, the French Participation Group, Harvard-Smithsonian Center for Astrophysics, Instituto de Astrofísica de Canarias, The Johns Hopkins University, Kavli Institute for the Physics and Mathematics of the Universe (IPMU)/University of Tokyo, Lawrence Berkeley National Laboratory, Leibniz Institut für Astrophysik Potsdam (AIP), Max-Planck-Institut für Astronomie (MPIA Heidelberg), Max-Planck-Institut für Astrophysik (MPA Garching), Max-Planck-Institut für Extraterrestrische Physik (MPE), National Astronomical Observatories of China, New Mexico State University, New York University, University of Notre Dame, Observatário Nacional/MCTI, The Ohio State University, Pennsylvania State University, Shanghai Astronomical Observatory, United Kingdom Participation Group, Universidad Nacional Autónoma de México, University of Arizona, University of Colorado Boulder, University of Oxford, University of Portsmouth, University of Utah, University of Virginia, University of Washington, University of Wisconsin, Vanderbilt University, and Yale University. This publication makes use of data products from the Wide-field Infrared Survey Explorer (Wright et al. 2010), which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. 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). Data Availability: The ZTF data underlying this article are available at The other data underlying this article will be shared on reasonable request to the corresponding author.
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC), Zwicky Transient Facility
Funding AgencyGrant Number
European Research Council (ERC)833031
Science and Technology Facilities Council (STFC)UNSPECIFIED
Gordon and Betty Moore FoundationGBMF5076
ZTF partner institutionsUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
European Research Council (ERC)677706
European Research Council (ERC)340040
Gaia Multilateral AgreementUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Participating InstitutionsUNSPECIFIED
University of MarylandUNSPECIFIED
Eotvos Lorand University (ELTE)UNSPECIFIED
Subject Keywords:binaries: eclipsing –novae, cataclysmic variables –white dwarfs
Issue or Number:4
Record Number:CaltechAUTHORS:20220131-501484900
Persistent URL:
Official Citation:J van Roestel, T Kupfer, M J Green, T L S Wong, L Bildsten, K Burdge, T Prince, T R Marsh, P Szkody, C Fremling, M J Graham, V S Dhillon, S P Littlefair, E C Bellm, M Coughlin, D A Duev, D A Goldstein, R R Laher, B Rusholme, R Riddle, R Dekany, S R Kulkarni, Discovery and characterization of five new eclipsing AM CVn systems, Monthly Notices of the Royal Astronomical Society, Volume 512, Issue 4, June 2022, Pages 5440–5461,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113168
Deposited By: Tony Diaz
Deposited On:01 Feb 2022 17:54
Last Modified:25 Apr 2022 21:10

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