Orbital Decay in an Accreting and Eclipsing 13.7 Minute Orbital Period Binary with a Luminous Donor

August 2023 • 2023ApJ...953L...1B

Authors • Burdge, Kevin B. • El-Badry, Kareem • Rappaport, Saul • Sunny Wong, Tin Long • Bauer, Evan B. • Bildsten, Lars • Caiazzo, Ilaria • Chakrabarty, Deepto • Chickles, Emma • Graham, Matthew J. • Kara, Erin • Kulkarni, S. R. • Marsh, Thomas R. • Nynka, Melania • Prince, Thomas A. • Simcoe, Robert A. • van Roestel, Jan • Vanderbosch, Zach • Bellm, Eric C. • Dekany, Richard G. • Drake, Andrew J. • Helou, George • Masci, Frank J. • Milburn, Jennifer • Riddle, Reed • Rusholme, Ben • Smith, Roger

Abstract • We report the discovery of ZTF J0127+5258, a compact mass-transferring binary with an orbital period of 13.7 minutes. The system contains a white dwarf accretor, which likely originated as a post-common envelope carbon-oxygen (CO) white dwarf, and a warm donor (T eff,donor = 16,400 ± 1000 K). The donor probably formed during a common envelope phase between the CO white dwarf and an evolving giant that left behind a helium star or white dwarf in a close orbit with the CO white dwarf. We measure gravitational wave-driven orbital inspiral with ~51σ significance, which yields a joint constraint on the component masses and mass transfer rate. While the accretion disk in the system is dominated by ionized helium emission, the donor exhibits a mixture of hydrogen and helium absorption lines. Phase-resolved spectroscopy yields a donor radial velocity semiamplitude of 771 ± 27 km s-1, and high-speed photometry reveals that the system is eclipsing. We detect a Chandra X-ray counterpart with L X ~ 3 × 1031 erg s-1. Depending on the mass transfer rate, the system will likely either evolve into a stably mass-transferring helium cataclysmic variable, merge to become an R CrB star, or explode as a Type Ia supernova in the next million years. We predict that the Laser Space Interferometer Antenna (LISA) will detect the source with a signal-to-noise ratio of 24 ± 6 after 4 yr of observations. The system is the first LISA-loud mass-transferring binary with an intrinsically luminous donor, a class of sources that provide the opportunity to leverage the synergy between optical and infrared time domain surveys, X-ray facilities, and gravitational-wave observatories to probe general relativity, accretion physics, and binary evolution.


IPAC Authors

Frank Masci

Senior Scientist

Ben Rusholme

Chief Engineer