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What happens when a star dies?

Fifty light years — that’s about 300,000,000,000,000 (300 quadrillion) miles — away from Earth is Lucy, a former star whose proverbial bulb has burned out.   And Lucy’s core has turned into a diamond.  In this case, the diamond is huge — the largest in the galaxy.  At 10 billion trillion trillion carats — 1 followed by 34 zeroes! — it’s, well, huge beyond imagination.  The largest terrestrial diamond, the Golden Jubilee Diamond, is about 500 carats — a 5, followed by two lonely zeroes.

How’d this happen?

When a star consumes all of its fuel, it burns out, leaving behind a white dwarf — a hot, crystalizing core.  For years, scientists have believed that the core, made mostly of carbon, turns into a diamond, but we have had no evidence supporting that thesis.  That all changed in 2004, when astronomers were able to use gong-like pulsations emanating from Lucy to determine that its core was a really big diamond and developed the model pictured above.  (Scientists use a similar method terrestrially, measuring the Earth’s seismic activity to answer questions about the makeup of the Earth’s core.)

And why “Lucy”?  The white dwarf’s official name is BPM 37038 — a nomenclature without meaning to lay people.  Lucy received her informal name upon the discovery of her diamond core — as a tribute to the Beatles.

Bonus fact:  BPM 37038 isn’t the first thing to be named after Lucy in the Sky with Diamonds.  In 1974, archeologists found a partial fossil of a prehistoric hominid, perhaps an evolutionary ancestor of humans, and named it Lucy – because the Beatles’ song had been played loudly and repetitively at the camp during excavation.

From the Archives: Pale Blue Dot: There’s a lot of stuff out there, and very very little of it is us.

Related: Diamonds.

Originally published

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