The curious case of NGC 6397

In a 1996 paper, a team led by John Wallin of George Mason University in Fairfax, Virginia, noted that a globular cluster passes through the Milky Way's disk every million years or so. The astronomers predicted that if such a passage happened near molecular clouds teetering on the brink of collapse, the globular's gravity would tip the balance, trigger the cloud's collapse, and spark an episode of star formation. The paper attracted little attention at the time.