CRYS­TALS TRAPPED IN ME­TE­ORITES RE­VEAL THE SUN’S VI­O­LENT PAST

Focus-Science and Technology - - DISCOVERIES -

The Sun burst into be­ing 4.6 bil­lion years ago, around 50 mil­lion years be­fore the Earth formed. This makes study­ing its early days in­cred­i­bly dif­fi­cult, as phys­i­cal ma­te­rial re­main­ing from this pe­riod is scarce. Now, a team from the Uni­ver­sity of Chicago has found crys­tals more than 4.5 bil­lion years old buried deep within me­te­orites that in­di­cate the Sun had a tu­mul­tuous early life.

Prior to the for­ma­tion of the plan­ets, the So­lar Sys­tem con­sisted of the Sun sur­rounded by a mas­sive pro­to­plan­e­tary disc of hot gas and dust that spi­ralled around it. As this gas and dust cooled down it co­a­lesced into min­er­als, in­clud­ing the blue hi­bonite crys­tals found em­bed­ded in me­te­orites that have landed on Earth.

Upon ex­am­in­ing the crys­tals us­ing a mass spec­trom­e­ter, the re­searchers were able to de­ter­mine that they con­tained traces of helium and neon, which the team be­lieves would have been cre­ated when high en­ergy pro­tons ejected from the young Sun struck the cal­cium and alu­minium atoms within the crys­tals.

“In ad­di­tion to fi­nally find­ing clear evidence in me­te­orites that disc ma­te­ri­als were di­rectly ir­ra­di­ated, our new re­sults in­di­cate that the So­lar Sys­tem’s old­est ma­te­ri­als ex­pe­ri­enced a phase of ir­ra­di­a­tion that younger ma­te­ri­als avoided,” said lead re­searcher Levke Kööp.

“We think this means that a ma­jor change oc­curred in the nascent So­lar Sys­tem af­ter the hi­bonites had formed,” he con­tin­ued. “Per­haps the Sun’s ac­tiv­ity de­creased, or maybe later-formed ma­te­ri­als were un­able to travel to the disc re­gions in which ir­ra­di­a­tion was pos­si­ble.”

4.5-bil­lion-year-old hi­bonite crys­tals (inset) have shed new light on the ear­li­est days of the So­lar Sys­tem (main im­age)

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