An eclipsing 47 min double white dwarf binary at 400 pc

• Published in: Monthly notices of the Royal Astronomical Society Vol. 525; no. 2; pp. 1814 - 1823
• Main Authors: Munday, James, Tremblay, P-E, Hermes, J J, Barlow, Brad, Pelisoli, Ingrid, Marsh, T R, Parsons, Steven G, Jones, David, Kepler, S O, Brown, Alex, Littlefair, S P, Hegedus, R, Baran, Andrzej, Breedt, Elmé, Dhillon, V S, Dyer, Martin J, Green, Matthew J, Kennedy, Mark R, Kerry, Paul, Lopez, Isaac D, Romero, Alejandra D, Sahman, Dave, Worters, Hannah L
• Format: Journal Article
• Language: English
• Published: Oxford University Press 21.08.2023
• Subjects: binaries: close; stars: individual: WDJ 022558.21−692025.38; gravitational waves; white dwarfs
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stad2347

ABSTRACT We present the discovery of the eclipsing double white dwarf (WD) binary WDJ 022558.21−692025.38 that has an orbital period of 47.19 min. Following identification with the Transiting Exoplanet Survey Satellite, we obtained time series ground based spectroscopy and high-speed multiband ULTRACAM photometry which indicate a primary DA WD of mass $0.40\pm 0.04\, \text{M}_\odot$ and a $0.28\pm 0.02\, \text{M}_\odot$ mass secondary WD, which is likely of type DA as well. The system becomes the third-closest eclipsing double WD binary discovered with a distance of approximately 400 pc and will be a detectable source for upcoming gravitational wave detectors in the mHz frequency range. Its orbital decay will be measurable photometrically within 10 yr to a precision of better than 1 per cent. The fate of the binary is to merge in approximately 41 Myr, likely forming a single, more massive WD.