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Astronomers Unveil Most Compact Known 3+1 Quadruple-Star System

TESS observations with supporting spectroscopy reveal a tightly bound configuration featuring the shortest outer orbit yet for this class.

Overview

  • TIC 120362137 was flagged in 2019–2024 TESS data as a triply eclipsing triple whose eclipse-timing variations pointed to a fourth star.
  • Measured periods place the inner binary at 3.28 days, the third star at 51.3 days, and the outer companion at 1,045.5 days, the shortest recorded outer orbit for a 3+1 quadruple.
  • The inner trio fits within a Mercury-scale region and the fourth orbits near a Jupiter-like scale, with separated spectra yielding masses of roughly 1.75, 1.36, 1.48, and about 1.0 solar masses.
  • Dynamical analyses indicate the architecture is currently stable, based on period ratios and numerical simulations.
  • Evolution models project inner mergers and a final double white-dwarf binary with an orbital period near 44 days, though reports conflict on the timescale and even on whether the study appears in Nature or Nature Communications.