After Dawson posted her work online, Stuart Taylor, an astronomer in Hong Kong, emailed her to say he had discovered the same correlation and presented it last summer at a conference in Beijing. But Taylor thought a star's high iron content might be an effect rather than a cause, because giant planets on elliptical orbits kick other planets into their star, boosting its iron level. "I think that our explanations are really complementary," Taylor says, because both processes may operate: An iron-rich star has more gas giants, causing more planets to crash into their sun.
In any event, it's a good thing "our" Jupiter stayed put. "No matter how a gas giant moves in, it's probably bad news for any small, Earth-sized planets that are in its way," Dawson says. "They would most likely get scattered into the sun."
Indeed, if the sun had been born with more iron, Uranus and Neptune might have grown into gas giants—and catapulted Jupiter or Saturn into our corner of the solar system.