21/28 December 2019 | New Scientist | 55>of Przybylski’s star, the sheer number of
lines makes it difficult to identify anything
with certainty.
In 2008, a team of astronomers claimed
some of the spectral lines from Przybylski’s
star were coming from a group of heavy
radioactive elements known as the actinides.
That was startling because, although actinides
can be produced in particle accelerators,
the heavier members of the group weren’t
thought to appear in nature. Not only are they
extremely difficult to produce, they decay
quickly too. Einsteinium, for instance, has
a half-life of just under 472 days. So any such
elements should be long gone from stars,
unless there is something to replenish them.
As a result, some astronomers suspect the
weird spectra from Przybylski’s star could be
the first evidence for an “island of stability” – a
fabled place beyond the existing periodic table
where superheavy elements long thought
impossible in nature are stable enough to
persist, perhaps for tens of millions of years.
The only place where these superheavy
elements might be created is within
supernovae, the explosive death throes of
certain stars. With that in mind, Vladimir
Dzuba at the University of New South Wales in
Australia and his colleagues suggested in 2017
that the shock wave from a nearby supernova
could have triggered the formation of
Przybylski’s star and loaded it with superheavy
elements. The idea is that those elements
are decaying slowly, ensuring the star’s
atmosphere contains an abundance of decay
products such as einsteinium. “It’s a beautifully
elegant solution,” says Jason Wright at
Pennsylvania State University, before pointing
out a major caveat: the original identification
of einsteinium may not be secure.
The reason for suspicion is that at
6600 kelvin, the surface temperature of
Przybylski’s star is hotter than most other
stars, and its atmosphere is likely to be hotter
still. In these conditions, atoms have their
outer electrons stripped away, turning them
into ions, and this changes the pattern of
spectral lines they emit. No lab has compiled
a complete catalogue of the spectral lines
emitted by such ions, so what we think is
einsteinium could well be a familiar element
that has been misidentified.
The one that refuses to die
A giant star blows itself to smithereens
somewhere in the universe every single day.
These supernovae are the final act of a massive
star’s life, and they occur only when a star