English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

AM CVn-type systems are ultracompact, helium-accreting binary systems whichare evolutionarily linked to the progenitors of thermonuclear supernovae andare expected to be strong Galactic sources of gravitational waves detectable toupcoming space-based interferometers. AM CVn binaries with orbital periods$\lesssim$ 20--23 min exist in a constant high state with a permanently ionisedaccretion disc. We present the discovery of TIC 378898110, a bright ($G=14.3$mag), nearby ($309.3 \pm 1.8$ pc), high-state AM CVn binary discovered in TESStwo-minute-cadence photometry. At optical wavelengths this is thethird-brightest AM CVn binary known. The photometry of the system shows a23.07172(6) min periodicity, which is likely to be the `superhump' period andimplies an orbital period in the range 22--23 min. There is no detectablespectroscopic variability. The system underwent an unusual, year-longbrightening event during which the dominant photometric period changed to ashorter period (constrained to $20.5 \pm 2.0$ min), which we suggest may beevidence for the onset of disc-edge eclipses. The estimated mass transfer rate,$\log (\dot{M} / \mathrm{M_\odot} \mathrm{yr}^{-1}) = -6.8 \pm 1.0$, isunusually high and may suggest a high-mass or thermally inflated donor. Thebinary is detected as an X-ray source, with a flux of $9.2 ^{+4.2}_{-1.8}\times 10^{-13}$ erg cm$^{-2}$ s$^{-1}$ in the 0.3--10 keV range. TIC 378898110is the shortest-period binary system discovered with TESS, and its largepredicted gravitational-wave amplitude makes it a compelling verificationbinary for future space-based gravitational wave detectors.

TIC 378898110: A Bright, Short-Period AM CVn Binary in TESS