For most binary stars, the theoretical and observed precession rates are in agreement, but the observed precession rate for the DI Herculis system is a factor of four slower than the theoretical rate, a disagreement that once was interpreted as evidence for a failure of general relativity. Here, both stars of DI Herculis are reported to rotate with their spin axes nearly perpendicular to the orbital axis, an observation that leads to the reconciliation of the theoretical and observed precession rates.
- Simon Albrecht
- Sabine Reffert
- Joshua N. Winn
