Scientific American - February 2019

February 2019, ScientificAmerican.com 17

NASA, JPL-CALTECH, CXC, ESA/NRAO AND J. RHO

SETI Institute

ASTROPHYSICS

Sand from

Stardust

Silica may originate in exploding stars

Astronomers have long argued that the phrase

“we are stardust” is more than poetic language.

Now new evidence adds another stanza to this

great cosmic verse.

Dust from silica—a common component

of  arth’s core, sandy beaches, concrete, glass

and even cell phones—has been detected with-

in the remnants of two supernovae in the Milky

 ay galaxy. These observations, described last

October in Monthly Notices of the Royal Astro-

nomical Society, Çß ̧þžlxîšx‰ßäîxþžlx³`xîšDî

silica originated within exploding stars.

“This is a rich result in that something so

common on  arth has now been found to be

created in the most violent explosions in the

universe,” says study co-author  aley  omez,

D³Däîß ̧³ ̧­xßDîDßlž†7³žþxßäžîāž³=D§xäÍ

“t’s an origin story.”

Astronomers have long pondered how

cosmic dust—whether it is composed of, say,

silica, carbon or iron—is created. nitially they

thought it formed when sunlike stars reached

̧§lDxD³lîšßxÿ ̧†­žšîāÿž³läjÿš ̧äx

gases were thought to condense into solid dust

ßDž³ä¥øäîDää³ ̧ÿ‹D¦xä… ̧ß­ž³D`šž§§āDî­ ̧-

sphere. But when observers detected dust in

galaxies so distant that they must have formed

soon after the big bang—well before sunlike

stars could have evolved—they knew there

must be another source.

They started to suspect that dust appeared

within supernovae explosions soon after the

universe formed, but astronomers have only

recently detected a handful of nearby super-

novae remnants sprinkled with dust. And Mika-

ko Matsuura, an astronomer who is also at Car-

lž†UøîÿDä³ ̧îž³þ ̧§þxlž³îšxäîølājäDāääšx

is excited to see further evidence.

f the dust within these early-universe super-

nova remnants is also found to contain silica,

îšx‰ßäîǧD³xîä­žšîšDþx§ ̧ ̧¦xl䞭ž§Dßî ̧

our own pale-blue dot. “t’s really interesting to

know we can make planets like  arth so soon”

in the universe’s existence,  omez says. “t

doesn’t take 1 billion years.” — Shannon Hall

Supernova remnant G54.1+0.3

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Austin B. Fletcher Professor of

Philosophy, Tufts University,

FFRF Honorary Director

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Photo by Brent Nicastro

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