Starship Asterisk*

The origin of stardust, which makes up most of the matter in our solar system, including us, is more complicated than previously thought, according to new observations of a mysterious object 15,000 light-years from Earth.

The Butterfly Nebula, also known as the Twin Jet Nebula, is an example of a so-called
bipolar planetary nebula. The object of this study, K4-47, is much less known, but
may be similar in appearance. Having nothing to do with planets, a planetary nebula
is a glowing, often colorful, shell of gas and dust shed into space by a dying star at
high speed. (Credit: ESA/Hubble & NASA; Acknowledgement: Judy Schmidt)

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Everything around you – your desk, your laptop, your coffee cup – in fact, even you – is made of stardust, the stuff forged in the fiery furnaces of stars that died before our sun was born. Probing the space surrounding a mysterious stellar corpse, scientists at the University of Arizona have made a discovery that could help solve a long-standing mystery: Where does stardust come from?

When stars die, they seed the cosmos around them with the elements that go on to coalesce into new stars, planets, asteroids and comets. Most everything that makes up Earth, even life itself, consists of elements made by previous stars, including silicon, carbon, nitrogen and oxygen. But this is not the whole story. Meteorites commonly contain traces of a type of stardust that, until now, was believed to form only in exceptionally violent, explosive events of stellar death known as novae or supernovae – too rare to account for the abundance preserved in meteorites.

Researchers at the UA used radio telescopes in Arizona and Spain to observe gas clouds in the young planetary nebula K4-47, an enigmatic object approximately 15,000 light-years from Earth. Classified as a nebula, K4-47 is a stellar remnant, which astronomers believe was created when a star not unlike our sun shed some of its material in a shell of outflowing gas before ending its life as a white dwarf.

To their surprise, the researchers found that some of the elements that make up the nebula – carbon, nitrogen and oxygen – are highly enriched with certain variants that match the abundances seen in some meteorite particles but are otherwise rare in our solar system: so-called heavy isotopes of carbon, nitrogen and oxygen, or ¹³C, ¹⁵N and ¹⁷O, respectively. These isotopes differ from their more common forms by containing an extra neutron inside their nucleus. ...

• Nature 564(7736):378 (20 Dec 2018) DOI: 10.1038/s41586-018-0763-1