In the periodic table of elements, "Au" stands for gold. The name "Aurelia" means "golden." It comes from the Latin adjective aureus, from the root word aurum: "gold." That in turn refers to the color yellow, specifically the color of the dawn; thus "Aurora," "goddess of the dawn, [who] renews herself every morning and flies across the sky, announcing the arrival of the sun," is a related name (Wikipedia). Julius Caesar's mother was named Aurelia. All accounts of her say she was respectable.
Aurelia Schober Plath, born in the U.S. in 1906, was the namesake of her own mother, Aurelia Grunwald (later Greenwood) Schober, born in Austria in 1887, when the name's popularity was near peaking in the U.S. according to census records. By 1906 the name was uncommon, ranking #496 in the Social Security Index tally of girls' names. It's trending upward in 2013, although it still isn't among the top 100 baby names.
Variants on the name Aurelia include Aurella, Auriel, and Aurielle.
Plath's volume Ariel (I'm using The Restored Edition here, but it's also true of the other edition) is stuffed with references to gold. Its first line says "Love set you going like a fat gold watch." Next page, "A ring of gold with the sun in it?" Then, "[i]n twenty-five years she'll be silver/ In fifty, gold." "The pure gold baby," "A gold filling," "my gold beaten skin/ Infinitely delicate," "gold-ruddy balls"-- you get it.
And of course if you've read about the poem "Medusa" you know "medusa" (Greek for "guardian or protectress") is a jellyfish grown to the familiar "dangling tentacles" stage, and that "Aurelia" is a genus of jellyfish, the most common kind, seen on the Atlantic beaches near Boston. Both Aurelia Plath and Sylvia knew that. Today we know there is a jellyfish discovered to be immortal.