A catalogue of ultracompact mass-transferring white dwarf binaries

¹ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
² Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks Street, Norman, OK 73019, USA
³ JILA, University of Colorado and National Institute of Standards and Technology, 440 UCB, Boulder, CO 80309-0440, USA
⁴ Anton Pannekoek Institute for Astronomy, University of Amsterdam, 1090 GE Amsterdam, The Netherlands
⁵ Department of Physics, University of California, Santa Barbara, CA 93106, USA

^★ Corresponding authors: mjgreenastro@gmail.com; j.c.j.vanroestel@uva.nl; tinlongsunny@ucsb.edu

Received: 1 April 2025
Accepted: 18 May 2025

Abstract

We present an overview and catalogue of all known mass-transferring binary systems that have white dwarf accretors and orbital periods shorter than 70 minutes, including the AMCVn-type binary systems and a number of related objects. We provide an overview of the literature background and describe recent breakthroughs, open questions, and connections to other fields. This overview is intended to provide a starting point for researchers who are relatively new to the fields of ultracompact binaries or AMCVn-type binaries. We define the scope of the catalogue (the criteria for inclusion) and describe its format and contents (what data have been included for each target). We also summarise the observed properties of the known mass-transferring ultracompact binaries, including their orbital periods and component stellar masses and radii. Our aim in presenting the catalogue is to provide a central resource to enable researchers to track the current status of the known sample. At the time of writing, the catalogue includes 123 confirmed binaries and 29 candidates. The catalogue is hosted on a public platform (Zenodo) with version control, and will be updated regularly.